Description:
FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[See section 10, Rule 13]

COMPOSITION FOR MAKING CONCRETE STRUCTURE HAVING ENHANCED PROPERTIES

Sarod Green Back LLP, an Indian Company of 7th Floor, 3A, Ecospace, Plot No. 2F/11, New Town, Rajarhat, West Bengal 700156, Kolkata, India.

THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED.
FIELD OF THE INVENTION
[01] The present invention relates to a composition for making concrete structure having enhanced properties and a process for preparing the same. Additionally, the invention relates to a method for preparing wet concrete mass suitable for making concrete structures.

BACKGROUND OF THE INVENTION
[02] Composition for making concrete structure predominantly comprise varying quantities of coarse aggregate, fine aggregate and binder. Apart from the above, the composition for making concrete structure may comprise varying quantities of additional materials which impart or enhance desired properties or reduce undesired properties in the concrete structure. Also, while making concrete structure, it is traditional to incorporate varying quantities of steel bars to impart or enhance desired properties in the concrete structure. The ultimate aim is to construct a concrete structure having exceptionally high strength and other performance characteristics, having a long life, at the lowest cost and having the least environmental impact.

[03] In the past, the Applicant has disclosed in Indian Patent Application No. 201631027942 a system for producing dry mix construction materials with improved engineering properties, the said system comprises: a plurality of raw material storage compartments (202) adapted for storing a plurality of raw materials (A, B, N); a material classification unit (204) adapted to classify at least one of the said plurality of raw materials (A, B, N) into a plurality of material subclasses (A1, A2, A3, An; B1, B21, B3, Bn; N1, N2, N3, Nn), wherein the said plurality of material sub-classes (A1, A2, A3, An; B1, B2, B3, Bn; N1, N2, N3, Nn) are stored in a plurality of material handling compartments (260); a chemical dispersion unit (220) having a plurality of chemical materials (CM1, CM2, CM3, CMn) stored in a plurality of chemical storage units (CS1,CS2, CS3, CSn); a material selection unit (210) working in conjugation with the said plurality of material handling compartments (260), said plurality of raw material storage compartments (202), and said plurality of chemical storage units (CS1, CS2, CS3, CSn), wherein the said material selection unit (210) is adapted for selecting at least one material sub-class (A1, A2, A3, An; B1, B2, B3, Bn; N1, N2, N3, Nn), at least one raw material (A, B, N), and at least one chemical material (CM1, CM2, CM3, CMn) as per a construction material grade provided by a user; and a plurality of conveying systems connecting at least one of the said plurality of material handling compartments (260), the said raw material storage compartments (202) and the said plurality of chemical storage units (CS1, CS2, CS3, CSn) with a blending unit (240), wherein the said blending unit (240) is adapted to blend the said at least one selected material sub-class (A1, A2, A3, An; B1, B2, B3, Bn; N1, N2, N3, Nn), the at least one selected raw material (A, B, N) and at least one chemical material (CM1, CM2, CM3, CMn) to produce a dry mix construction material blend.

[04] The Applicant had additionally disclosed in Indian Patent Application No. 201731003857 an engineered concrete binder composition having overall reduced clinker factor, the concrete binder composition binding concrete aggregates to produce concrete material, wherein the said concrete binder composition comprises: at least one primary binder in a ratio of 10-60 weight percent, wherein the primary binder is selected from a primary material group having spontaneous hydration property; at least one secondary binder in a ratio of 40-90 weight percent, wherein the secondary binder is selected from a secondary material group having induced hydration property; the said primary binder comprises particles having a mode average particle diameter ranging from ¼th to 1/25th of a smallest fine aggregate particle mode average particle diameter, the smallest fine aggregate mode average particle diameter referring to mode average particle diameter of smallest fine particles present in the concrete aggregates; the said secondary binder comprises particles having a mode average particle diameter ranging from ¼th to 1/625th of the smallest fine aggregate mode average particle diameter; and the said primary material group and the said secondary material group form a Macro-Micro-Nano particle lattice arrangement to increase strength characteristics and durability index of the concrete material.

[05] The Applicant had additionally disclosed in Indian Patent Application No. 201731024816 a method for manufacturing a dry mix construction material, said method comprising:
receiving user-input indicative of initial design parameters for manufacturing the dry mix construction material;
selecting at least one dry mix construction material from a plurality of dry mix construction material designs based on the initial design parameters;
based on the at least one dry mix construction material thus selected, selecting (a) at least one hydraulic material, (b) at least one fine aggregate, (c) a coarse aggregate, (d) at least one powder-based additive, and (e) at least one optional pozzolanic material,
the selection further comprising:
selecting the at least one hydraulic material from a plurality of subgroups of hydraulic materials; selecting the at least one fine aggregate from a plurality of sub-groups of fine aggregates;
selecting the at least one powder-based additive from a plurality of sub-groups of powder-based additives and
selecting the at least one optional pozzolanic material from a plurality of sub-groups of pozzolanic material; and
mixing (a) the hydraulic material, (b) the fine aggregate, (c) the coarse aggregate, (d) the powder-based additive, and (e) the optional pozzolanic material thus selected to obtain the at least one dry mix construction material.

[06] The Applicant had additionally disclosed in Indian Patent Application No. 201731020956 a method for producing a compact and highly dense construction material, the method comprises steps of:
determining a smallest fine aggregate fraction of a raw construction material via applying a gradation process;
determining a mode average particle diameter (D) of the said smallest fine aggregate fraction; and
setting up a series of lattice void fillers ranging from a macro to Nano particle size level, wherein the said series of lattice void fillers correspond to the said mode average particle diameter (D) of the said smallest fine aggregate fraction of the raw construction material;
wherein the said series of lattice void fillers comprises material particles having spontaneous hydration property and material particles having induced hydration property;
the material particles having induced hydration property is selected from: a normal pozzolanic material having a mode average particle diameter (D1), wherein the said pozzolanic material is selected from a fly ash, a blast furnace slag, a volcanic ash material, a quartz material; and a
mechanically modified pozzolanic material having a mode average particle diameter ranging from (D2) to (DN), wherein the said mechanically modified pozzolanic material is selected from a mechanically modified fly ash, a mechanically modified blast furnace slag, a mechanically modified volcanic ash material, a mechanically modified quartz material.

[07] The Applicant had additionally disclosed in Indian Patent Application No. 201731027025 a method of producing a compact and highly dense construction material, the method comprises a step of mixing:
a first set of cementitious material having mode average particle diameter (Dl) in the range of 1/3 to 1/5 of a mode average particle diameter (D) of a smallest fine aggregate fraction of a raw construction material;
a second set of cementitious material having mode average particle diameter (D2) in the range of 1/3 to 1/5 of the mode average particle diameter (Dl) of the first set of cementitious material;
a third set of cementitious material having mode average particle diameter (D3) in the range of 1/3 to 1/5 of the mode average particle diameter (D2) of the second set of cementitious material; and
a fourth set of cementitious material have mode average particle diameter (D4) in the range of 1/3 to 1/5 of the mode average particle diameter (D3) of the third set of cementitious material to obtain the construction material.

[08] The Applicant had additionally disclosed in Indian Patent Application No. 201731032483 a method of producing raw materials for use in producing a dry mix construction material, the method comprises the steps of:
obtaining a coarse aggregate having a mode average particle diameter (Dl) in a predetermined range;
obtaining a fine aggregate having a mode average particle diameter (D2) in range of 1/3 to 1/5 of the mode average particle diameter (Dl) of the coarse aggregate;
weighing a load of the coarse aggregate such that an amount (Wl) of the coarse aggregate is in a range of 25 to 50 weight percentage (wt%) of the dry mix construction material;
weighing a load of the fine aggregate such that an amount (W2) of the fine aggregate is in a range of 25 to 42 weight percentage (wt%) of the dry mix construction material; and
mixing the weighed amount (Wl) of the coarse aggregate and the weighed amount (W2) of the fine aggregate to obtain a first mixture for use in producing the dry mix construction material.

[09] The Applicant had additionally disclosed in Indian Patent Application No. 201831022452 an engineered concrete binder composition, comprising: a first set of cementitious material comprising hydraulic material optionally along with pozzolanic material; and a second set of cementitious material comprising pozzolanic material and pozzolan activator material, the second set of cementitious material having a mode average particle diameter (D2) not greater than 1/3 of the mode average particle diameter of the first set of cementitious material (Dl).

[010] The Applicant had additionally disclosed in Indian Patent Application No. 201831019418 a process for preparing and packaging of dry mix construction material, said process comprising the steps of: determining a rate of moisture absorption of a raw material (MARx) used for preparing the dry mix construction material, the rate of moisture absorption being in relation to a prevailing environment condition; and controlling, based on the rate of moisture absorption thus determined, at least one parameter pertaining to preparing and packaging of dry mix construction material.

[011] The Applicant had additionally disclosed in Indian Patent Application No. 201932006254 an engineered concrete binder composition comprising: at least one hydraulic material; at least one pozzolanic material; and optionally at least one additive; an amount of the hydraulic material (W1) being in a range of 20 to 60 wt.% of the composition; an amount of the pozzolanic material (W2) being in a range of 40 to 90 10 wt.% of the composition; and an amount of the at least one additive (W3) being in a range of 0 to 15 wt.% of the composition; each of the hydraulic material and the pozzolanic material comprising a first fraction, a second fraction and a third fraction with: the first fraction having Blaine’s fineness in a range of 3000 to 4000 cm2 /gm and mode average particle size (MAPS) in a range of 70 to 80 microns; the second fraction having Blaine’s fineness in a range of 10000 to 15000 cm2 /gm and mode average particle size (MAPS) in a range of 20 to 30 microns; and the third fraction having Blaine’s fineness in a range of 40000 to 50000 cm2 /gm and mode average particle size (MAPS) in a range of 3 to 8 microns.

[012] The Applicant had additionally disclosed in Indian Patent Application No. 201931040382 a process for preparing a concrete slurry, comprising: mixing hydraulic material with water to obtain a first slurry; and mixing coarse aggregate and fine aggregate either simultaneously or in any sequence with the first slurry to obtain the concrete slurry.

[013] The Applicant had additionally disclosed in Indian Patent Application No. 202031031282 a concrete mixture having enhanced static and dynamic properties, said concrete mixture comprising: coarse aggregates in an amount of 20 to 50 wt.% of the concrete mixture; fine aggregates in an amount of 15 to 45 wt.% of the concrete mixture; binder material in an amount of 10 to 25 wt.% of the concrete mixture; and optionally at least one additive in an amount of 0 to 5 wt.% of the concrete mixture; characterized in that: the coarse aggregate is having a layer of silica fumes thereupon, an amount of silica fumes being in the range of 0.1 to 5.0 wt.% of the coarse aggregate, the silica fumes having a diameter in the range of 1 nano meter to 10 microns; and the concrete mixture further comprises fibres having a length in the range of 5 mm to 50 mm and internal diameter in the range of 1 mm to 5 mm.

[014] The Applicant had additionally disclosed in Indian Patent Application No. 202131020255 a method to produce a concrete material having optimized strength and particle packing properties, wherein, the method comprises: a micro characterization step of a plurality of starting cementitious materials, wherein, the said micro characterization step provides at least one cementitious material having uniform strength; a micro characterization step of at least one starting pozzolanic material; wherein, the said micro characterization step provides at least one pozzolanic material having uniform blain fineness; grinding the said at least one cementitious material having uniform strength and the said at least one pozzolanic material having uniform blain fineness to get at least one cementitious material having a required Blaine fineness and at least one pozzolanic material having a required Blaine fineness; and preparing the said concrete material by mixing a material selected from at least one starting cementitious material, at least one cementitious material having uniform strength, at least one cementitious material having a required Blaine fineness, at least one starting pozzolanic material, at least one pozzolanic material having uniform blain fineness, at least one pozzolanic material having a required Blaine fineness, at least one aggregate material, at least one additive material or a mixture thereof.

[015] The Applicant had additionally disclosed in Indian Patent Application No. 202231045976 a computer implemented method to generate a multidimensional property matrix to produce a concrete material with predictable quality and strength, wherein, the method comprises: generating a database of a plurality of binder attributes and a plurality of concrete attributes, wherein, the said binder attributes and the concrete attributes have a predefined value, a laboratory determined value, or a field trial value; generating a two-dimensional property matrix through a processing system, wherein, the said two-dimensional property matrix comprises a base column of binder attributes, and a base row of concrete attributes, thereby providing a plurality of concrete property parameter rows; generating the multidimensional property matrix by changing the value of binder attributes; and generating a concrete property trend line through the processing system, wherein, the concrete property trend line is generated by linear interpolation of the said plurality of concrete property parameter rows, wherein, the said trend line provides the concrete material with desired quality and strength.

[016] It is well known that during the concreting process the coarse aggregate and the fine aggregate along with the binder particles are closely packed to form the hard rock like concrete structure. Thus, packaging efficiency of the binder and aggregates greatly impacts the strength and durability of the concrete structure. The conventional method for increasing the packaging efficiency of the concrete and for producing a closely packed concrete mixture includes mixing binder, fine aggregate materials, and coarse aggregate materials in an optimum percentage. In many instances, the packaging efficiency of the concrete is low and hence, there exists a need to provide a concrete mixture that has high packaging efficiency thereby and maximize the strength and durability of the construction material.

[017] A methodology of making concrete mixture consists of a scientific way of combining the above materials (i.e. coarse aggregate, fine aggregate, and a binder portion). By varying the ratios and proportions of the aforesaid ingredients, concrete mixtures with different strength, rheological and long-term performance-based properties are obtained. In this whole process, a dense, heterogeneous composite is created, which primarily consists of two different phases namely:
• The coarse aggregate phase; and
• The mortar phase, which is a combination of fine aggregate and binder.

[018] The coarse aggregate phase consists of coarse aggregates, usually crushed stones made of hard rock materials such as igneous granite/basalt, limestone, etc. The binder phase comprises of the fine aggregate and the binder phase. Additionally, there are present two levels of Interfacial Transition zone (ITZ layers). The first level Interfacial Transition zone (first ITZ layer) exists between the coarse aggregate phase and the mortar phase, predominantly the binder portion of the mortar. The second level Interfacial Transition zone (second ITZ layer) exists between the fine aggregate and the binder in the mortar phase.

[019] In the past, the Applicant had observed that providing a layer of silica fumes on the coarse aggregate as disclosed in Indian Patent Application No. 202031031282 tends to reduce the first level Interfacial Transition zone (first ITZ layer). Reduction in the first level Interfacial Transition zone (first ITZ layer) leads to reduction in the moisture content on the coarse aggregate, reduction in a size of vacant layer surrounding the coarse aggregate, reduction in concentration of calcium hydroxide (CaOH2) in the first level Interfacial Transition zone (first ITZ layer). These aspects lead to improvement of the static strength of the concrete structure. However, this approach did not have any substantial impact on the second level Interfacial Transition zone (third ITZ layer).

[020] In the prior art, attempts have been made to provide different types of coatings on the fine aggregate. For instance, U. S. Patent No. 9359253 describes providing a polymer coated fine aggregate having the granules individually coated with discrete, individual, and discontinuous particles of a powder comprising a water-absorbing polymer.

[021] By way of another example, EP Patent Publication No. 2067753 describes concrete mix comprising hydraulic cementitious material, aggregates and water, wherein at least a portion of the aggregates in the total mix is coated externally with a well-bonded polymer layer of at least 1 µm in average thickness, said layer comprising a polymer having a high elongation and high energy-absorption capacity at the temperatures at which the concrete is designed to be used. Firstly, it should be noted that The polymer comprises latex, natural rubber, synthetic rubber and/or constituents thereof and also it should be noted that the range of aggregates sizes used in the mix which are to be coated, and the mass fraction of aggregates to be coated, depend on the top size of the aggregates to be used in the concrete in question. It represents a significant percentage of the coarsest fraction of these aggregates. It preferably represents at least 30% of the aggregates with effective diameters (or sieve sizes) that are above 50% of the maximum aggregate diameter, and even more preferably, at least 50% of those aggregates with effective diameters (or sieve sizes) larger than 75% of the maximum aggregate diameter.

[022] By way of yet another example, there exist a lot of documents that describe polymer-coated sand for making concrete composition. For example, silica sand coated with an elastomeric material has been described in U.S. Pat. No. 5,043,320. By way of another example, U.S. Patent Application Publication No. 20060100342 describes silica sand coated with either elastomeric materials or thermoplastic polymers.

[023] By way of another example, there exist a lot of documents that describe graphene coated sand. For example, “Graphene oxide-coated sand for improving performance of cement composites” by Hoan D. Nguyen et al., Cement and Concrete Composites, Volume 124, November 2021, 104279 discloses chemically bonding Graphene oxide (GO) on sand through amino functional groups to avoid the GO agglomeration in the cement matrix. By way of another example, there is disclosed Hydrated sodium silicate (Na2O.nSiO2, 0.06–0.203 g/cm3 density) was employed by Kaga, M.; Yonekura, R. Estimation of strength of silicate grouted sand. Soils Found. 1991, 31, 43–59 for stabilization of five sands of diverse gradations, with emphasis on the role of sand relative density (Dr—that is, a packing proxy parameter) on strength of the composites. Colloidal nano-silica (NS) hydrosols are electrochemically stabilized, polymerized amorphous silica in low viscosity solutions, and in the form of hydrated gels, silica globules or pellicles.

[024] Despite the aforesaid advancements made in the technology, there exists a need to provide concrete composition using which it is possible to make concrete structure having exceptionally high strength, having a long life, at the lowest cost and having the least environmental impact.

SUMMARY OF THE INVENTION
[025] This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

[026] In a fist aspect of the invention there is provided a composition for making concrete structure having enhanced properties, said composition comprises coarse aggregates in an amount of 20 to 50 wt.% of the composition, fine aggregates in an amount of 15 to 45 wt.% of the composition, and optionally binder material in an amount of 10 to 25 wt.% of the composition; and optionally at least one additive in an amount of 0 to 5 wt.% of the composition, the coarse aggregate optionally comprising a layer of micro silica thereupon; and the fine aggregate comprising a layer of micro silica thereupon, an amount of micro silica being in the range of 0.1 to 5.0 wt.% of the fine aggregate.

[027] In an embodiment of the invention, the composition is in at least two-part form comprising:
(a) a first part comprising
(i) coarse aggregates in an amount of 20 to 50 wt.% of the composition,
(ii) the fine aggregates in an amount of 15 to 45 wt.% of the composition, and
(iii) optionally at least one additive,
the coarse aggregate optionally comprising a layer of micro silica thereupon; and the fine aggregate comprising a layer of micro silica thereupon, an amount of micro silica being in the range of 0.1 to 5.0 wt.% of the fine aggregate; and
(b) a second part comprising:
(i) the binder material in an amount of 10 to 25 wt.% of the composition; and
(ii) optionally at least one additive;
the at least one additive is present in an amount of 0 to 5 wt.% of the composition.

[028] In an embodiment of the invention, the binder material comprises a first material selected from a group comprising of Portland cement, modified Portland cement, or masonry cement, hydraulic hydrated lime, white cement, calcium aluminate cement, silicate cement, phosphate cement, high-alumina cement, magnesium oxychloride cement, oil well cements, and combinations thereof.

[029] In another embodiment of the invention, the binder material optionally comprises a second material selected from a group comprising of blast furnace slag (including Ground Granulated Blast Furnace Slag (GGBS)), chemically modified blast furnace slag, Lightweight Expanded Clay Aggregate (LECA), Calcined Clay (Meta star), Red Brick Dust (RBD), Tile and Yellow Brick Dust (YBD) and combinations thereof.

[030] In yet another embodiment of the invention, the binder material optionally comprises a third material selected from a group comprising of fly ash, chemically modified fly ash, Pulverized Fuel Ash (PFA), Rice Husk Ash (RHA), volcanic ash material, finely ground quartz material, chemically modified quartz, pond ash, and combination thereof.

[031] In still another embodiment of the invention, the binder material optionally comprises a fourth material selected from a group comprising sodium sulphate, micro silica, lime, and combination thereof.

[032] In a further embodiment of the invention, the at least one additive is selected from a group comprising of Melamine, Lignosulphonate, Sulphonated Naphthalene Formaldehyde, Sulphonated melamine formaldehyde, Polycarboxylate based compound, carbon nanotube (CNT) based additives, sodium hydroxide, potassium hydroxide, magnesium hydroxide and combinations thereof.

[033] In a furthermore embodiment of the invention, the micro silica has a size in the range of 1 nano meter to 10 microns.

[034] In an embodiment of the invention, the fine aggregate further comprises activated calcium hydroxide.

[035] In another embodiment of the invention, the composition is dry and is adapted to be mixed with water in an amount of 4 to 8 wt.% of the composition for making a wet concrete mass suitable for making concrete structures.

[036] In yet another embodiment of the invention, the coarse aggregate comprises the layer of micro silica thereupon, and an amount of micro silica being in the range of 0.1 to 2.0 wt.% of the coarse aggregate.

[037] In still another embodiment of the invention, the composition optionally comprises fibers in an amount of 1 to 5 wt% of the composition, the fibers having a length in the range of 5 mm to 50 mm.

[038] In a further embodiment of the invention, the fibers are solid and have an external diameter in the range of 1.1 to 5.2 mm.

[039] In a furthermore embodiment of the invention, the fibers are hollow and have an external diameter in the range of 1.1 to 6 mm and an internal diameter in the range of 1 to 5 mm.

[040] In an embodiment of the invention, the binder material comprises two or more fractions that are different from each other in term of their D-90 size or in terms of their mode average particle size (MAPS).

[041] In another embodiment of the invention, the binder material comprises a first binder size fraction having D90 size or MAPS in the range of 70 to 80 microns; an amount of the first binder size fraction being in a range of 50 to 85 wt.% of the amount of the binder material; a second binder size fraction having D90 size or MAPS in the range of 20 to 30 microns; an amount of the second binder size fraction being in a range of 20 to 40 wt.% of the amount of the first binder size fraction; a third binder size fraction having D90 size or MAPS in the range of 3 to 8 microns; an amount of the third binder size fraction being in a range of 20 to 40 wt.% of the amount of the second binder size fraction; and optionally a fourth binder size fraction having D90 size or MAPS in the range of 0.01 to 2 microns; the fourth binder size fraction constituting a remaining amount of the binder material.

[042] In yet another embodiment of the invention, the first material forming part of the binder material comprises a first material first size fraction having D90 size or MAPS in the range of 70 to 80 microns; an amount of the first material first size fraction being in a range of 50 to 85 wt.% of the amount of the first material; a first material second size fraction having D90 size or MAPS in the range of 20 to 30 microns; an amount of the first material second size fraction being in a range of 20 to 40 wt.% of the amount of the first material first size fraction; and optionally a first material third size fraction having D90 size or MAPS in the range of 3 to 8 microns; the first material third size fraction constituting a remaining amount of the binder material.

[043] In still another embodiment of the invention, the second material forming part of the binder material comprises a second material first size fraction having D90 size or MAPS in the range of 70 to 80 microns; an amount of the second material first size fraction being in a range of 50 to 85 wt.% of the amount of the second material; a second material second size fraction having D90 size or MAPS in the range of 20 to 30 microns; an amount of the second material second size fraction being in a range of 20 to 40 wt.% of the amount of the second material first size fraction; a second material third size fraction having D90 size or MAPS in the range of 3 to 8 microns; the second material third size fraction constituting a remaining amount of the binder material; an amount of the second material third size fraction being in a range of 20 to 40 wt.% of the amount of the second material second size fraction; and optionally a second material fourth size fraction having D90 size or MAPS in the range of 0.01 to 2 microns; the second material fourth size fraction constituting a remaining amount of the second material.

[044] In a second aspect of the invention, there is provided a method for preparing wet concrete mass suitable for making concrete structures, said process comprising: mixing a composition comprising coarse aggregates in an amount of 20 to 50 wt.% of the composition, fine aggregates in an amount of 15 to 45 wt.% of the composition, and optionally binder material in an amount of 10 to 25 wt.% of the composition; and optionally at least one additive in an amount of 0 to 5 wt.% of the composition, the coarse aggregate optionally comprising a layer of micro silica thereupon; and the fine aggregate comprising a layer of micro silica thereupon, an amount of micro silica being in the range of 0.1 to 5.0 wt.% of the fine aggregate with water in an amount of 4 to 8 wt.% of the composition to obtain the wet concrete mass.

[045] In an embodiment of the invention, the composition is in at least two-part form comprising:
(a) a first part comprising the coarse aggregates, the fine aggregates, and optionally at least one additive, the coarse aggregate optionally comprising a layer of micro silica thereupon; and the fine aggregate comprising a layer of micro silica thereupon, an amount of micro silica being in the range of 0.1 to 5.0 wt.% of the fine aggregate; and
(b) a second part comprising the binder material; and optionally at least one additive; and
the step of mixing comprises mixing the second part comprising the binder material and optionally the at least one additive with water to obtain a first slurry; mixing the first part comprising the coarse aggregates, optionally comprising a layer of micro silica thereupon, the fine aggregates comprising the layer of micro silica thereupon and optionally the at least one additive with the first slurry in any sequence to obtain the wet concrete mass.

[046] In a third aspect of the invention, there is provided a method for preparing the composition said process comprising:
obtaining coarse aggregates optionally comprising a layer of micro silica thereupon;
obtaining fine aggregates comprising a layer of micro silica thereupon, an amount of micro silica being in the range of 0.1 to 5.0 wt.% of the fine aggregate;
mixing the coarse aggregate thus obtained with the fine aggregate thus obtained such that the coarse aggregates optionally comprising the layer of micro silica is in an amount of 20 to 50 wt.% of the composition, and the fine aggregates comprising the layer of micro silica thereupon is present in an amount of 15 to 45 wt.% of the composition;
providing a binder material in an amount of 10 to 25 wt.% of the composition; and
optionally providing at least one additive the at least one additive being present in an amount of 0 to 5 wt.% of the composition.

[047] In another embodiment of the invention, the coarse aggregate comprises the layer of micro silica thereupon, and the same is obtained by: contacting wet coarse aggregate with powder micro silica to obtain wet coated coarse aggregate; and drying the wet coated coarse aggregate to obtain the coarse aggregate having a layer of micro silica thereupon; the amount of micro silica, and the amount of water being such that the coarse aggregate comprises 0.1 to 2.0 wt.% of micro silica layer thereupon, the weight percentage being based on a weight of the coarse aggregate.

[048] In another embodiment of the invention, the fine aggregate comprising the layer of micro silica thereupon is obtained by: contacting wet fine aggregate with powder micro silica to obtain wet coated fine aggregate; and drying the wet coated fine aggregate to obtain the fine aggregate having a layer of micro silica thereupon; the amount of micro silica, and the amount of water being such that the fine aggregate comprises 0.1 to 5.0 wt.% of micro silica layer thereupon, the weight percentage being based on a weight of the fine aggregate.

[049] In an embodiment of the invention, the fine aggregate further comprises activated calcium hydroxide and the same is obtained by: obtaining a wet coated fine aggregate comprising fine aggregate, calcium carbide, water and micro silica; igniting the wet coated fine aggregate so as to dry the wet coated fine aggregate to obtain a mixture comprising activated calcium hydroxide and fine aggregate having a layer of micro silica thereupon; the amount of micro silica, and the amount of water being such that the fine aggregate comprises 0.1 to 5.0 wt.% of micro silica layer thereupon, the weight percentage being based on a weight of the fine aggregate.

[050] To further clarify advantages and features of the present invention, a more particular description of the invention will be rendered by reference to specific embodiments thereof. It is appreciated that only typical embodiments of the invention are provided herein below and that the same should not to be considered limiting the scope of the invention.

DETAILED DESCRIPTION OF THE INVENTION:
[051] For the purpose of promoting an understanding of the principles of the invention, reference will now be made to the embodiment illustrated in the figures and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated system, and such further applications of the principles of the invention as illustrated therein being contemplated as would normally occur to one skilled in the art to which the invention relates.

[052] It will be understood by those skilled in the art that the foregoing general description and the following detailed description are exemplary and explanatory of the invention and are not intended to be restrictive thereof.

[053] Reference throughout this specification to “an aspect”, “another aspect” or similar language means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrase “in an embodiment”, “in another embodiment” and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment.

[054] The terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a composition comprises a list of ingredients does not include only those ingredients, but may include other ingredients not expressly listed. Similarly, process or method that comprises a list of steps does not include only those steps but may include other steps not expressly listed or inherent to such process or method.

[055] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The system, methods, and examples provided herein are illustrative only and not intended to be limiting.

[056] Groupings of alternative elements or embodiments of the invention disclosed herein are not to be construed as limitations. Each group member can be referred to and claimed individually or in any combination with other members of the group or other elements found herein. One or more members of a group can be included in, or deleted from, a group for reasons of convenience and/or patentability. When any such inclusion or deletion occurs, the specification is herein deemed to contain the group as modified thus fulfilling the written description of all Markush groups used in the appended claims.

[057] The term “strength” or “compressive strength” of concrete is the most common performance measure used by the engineer in designing buildings and other structures. The compressive strength is measured by breaking cylindrical or cubical concrete specimens in a compression-testing machine. The compressive strength is calculated from the failure load divided by the cross-sectional area resisting the load and reported in units of pound-force per square inch (psi) in US Customary units or Mega Pascal (MPa) in SI units.

[058] Coarse aggregate is a granular material made of small stones, such as gravel, that is used in concrete. According to Indian Standard IS 383-2016, coarse aggregate in concrete is a material that is mainly retained on a 4.75 mm IS sieve. It can be uncrushed gravel or stone that is the result of natural rock disintegration; crushed gravel or stone; partially crushed gravel or stone or manufactured from other sources, such as recycled concrete aggregate (RCA) or recycled aggregate (RA). In the specification, the term “coarse aggregate” is intended to include the materials which fall within the ambit of Indian Standard IS 383-2016. The “coarse aggregate” is more particularly intended to cover the materials satisfying the requirement as set out in Table 1 provided herein below:

Table 1: Characteristics of Coarse Aggregate:
IS Sieve Designation Percentage passing for single-sized aggregate of nominal size Percentage passing for graded -sized aggregate of nominal size
63mm 40mm 20mm 16mm 12.5mm 10mm 40mm 20mm 16mm 12.5mm
20 mm 0 to 5 0 to 20 85-100 100 - - 30 – 70 95-100 100 100
12.5 mm - - - - 85-100 100 - - - 90-100
10 mm 0 to 5 0 to 5 0 to 20 0 to 30 0 to 45 85 – 100 10-35 25-55 30-70 40-85

[059] Fine aggregate is intended to include the materials which fall within the ambit of Indian Standard IS 383-2016. According to the Indian Standard (IS) 383:2016, fine aggregate is a material that passes through a 4.75 mm IS sieve and contains only a limited amount of coarser material. The “fine aggregate” is more particularly intended to cover the materials satisfying the requirement as set out in Table 2 provided herein below:

Table 2: Fine Aggregate
IS Sieve Designation Percentage Passing for
Grading Zone I Grading Zone II Grading Zone III Grading Zone IV
10 mm 100 100 100 100
4.75 mm 90-100 90-100 90-100 95-100
2.36 mm 60-95 75-100 85-100 95-100
1.18 mm 30-70 55-90 75-100 90-100
600 microns 15-34 35-39 60-79 80-100
300 microns 5-20 8-30 12-40 15-50
150 microns 0-10 0-10 0-10 0-15

[060] The mode average particle size as provided herein is understood to be the peak of the particle frequency distribution curve, obtained from PSD analysis. In simple words, the mode is the highest peak seen in the particle frequency distribution curve. The mode represents the particle size (or size range) most commonly found in the particle frequency distribution curve within 1 standard deviation in the normal distribution curve.

[061] Further, the particle-size distribution (PSD) analysis is termed herein as the mathematical expression of finding about the ratio/proportion of various particle size ranges which are present in given raw construction material. Generally, volume, area, length, and quantity are used as standard dimensions for determining the particle amount present in the raw construction material. However, the volume of the raw construction material sample is considered as the easiest dimension and/or way of finding out the ratio of various particles size ranges present in the given raw construction sample.

[062] Embodiments of the present invention will be described below in detail with reference to the accompanying figures.

[063] The present invention provides a composition for making concrete structure having enhanced properties, said composition comprises coarse aggregates in an amount of 20 to 50 wt.% of the composition, fine aggregates in an amount of 15 to 45 wt.% of the composition. In an embodiment the concrete structure optionally comprises a binder material in an amount of 10 to 25 wt.% of the composition. In an embodiment the concrete structure optionally comprises at least one additive in an amount of 0 to 5 wt.% of the composition. In an embodiment of the invention, the coarse aggregate optionally comprises a layer of micro silica thereupon. In an embodiment of the invention, the fine aggregate comprises a layer of micro silica thereupon. In an embodiment of the invention, an amount of micro silica coated on the fine aggregate is in the range of 0.1 to 5.0 wt.% of the fine aggregate.

[064] In an embodiment of the invention, the composition is in at least two-part form comprising a first part and a second part. The composition may be in three art form also.

[065] In case the composition is in two-part form, the first part comprises (i) coarse aggregates in an amount of 20 to 50 wt.% of the composition, (ii) the fine aggregates in an amount of 15 to 45 wt.% of the composition, and (iii) optionally at least one additive. As stated above, the coarse aggregate may optionally comprise a layer of micro silica thereupon and the fine aggregate comprises a layer of micro silica thereupon, wherein an amount of micro silica coated on the fine aggregate is in the range of 0.1 to 5.0 wt.% of the fine aggregate.

[066] In yet another embodiment of the invention, the micro silica for coating on the fine aggregate preferably has a diameter (D90 size) in the range of 1 nano meter to 10 microns. In an alternative embodiment of the invention, the micro silica for coating on the fine aggregate preferably has a diameter in the range of 1 nano meter to 1 micron. In an alternative embodiment of the invention, the micro silica for coating on the fine aggregate preferably has a diameter in the range of 1 nano meter to 0.1 microns. In still another alternative embodiment of the invention, the micro silica for coating on the fine aggregate has a diameter in the range of 10 nano meter to 10 microns. In a further alternative embodiment of the invention, the micro silica for coating on the fine aggregate has a diameter in the range of 20 nano meter to 1 micron. In a further alternative embodiment of the invention, the micro silica for coating on the fine aggregate has a diameter in the range of 50 nano meter to 1 micron. In a further alternative embodiment of the invention, the micro silica for coating on the fine aggregate has a diameter in the range of 75 nano meter to 1 micron. In a further alternative embodiment of the invention, the micro silica for coating on the fine aggregate has a diameter in the range of 100 nano meter to 2.5 microns. In a further alternative embodiment of the invention, the micro silica for coating on the fine aggregate has a diameter in the range of 150 nano meter to 500 nano meter.

[067] In still another embodiment of the invention, the micro silica for coating on the fine aggregate is in the range of 0.1 to 5.0 wt.% of the fine aggregate. In an alternative embodiment of the invention, the micro silica for coating on the fine aggregate is in the range of 0.1 to 3.0 wt.% of the fine aggregate. In still another alternative embodiment of the invention, the micro silica for coating on the fine aggregate is in the range of 0.1 to 2.0 wt.% of the fine aggregate. In a further alternative embodiment of the invention, the micro silica for coating on the fine aggregate is in the range of 0.1 to 1.0 wt.% of the fine aggregate. In a further alternative embodiment of the invention, the micro silica for coating on the fine aggregate is in the range of 0.5 to 2.0 wt.% of the fine aggregate. In a further alternative embodiment of the invention, the micro silica for coating on the fine aggregate is in the range of 0.5 to 1.0 wt.% of the fine aggregate.

[068] In a further embodiment of the invention, the coarse aggregate comprises micro silica coated thereupon. In such a case, the micro silica for coating on the coarse aggregate preferably has a diameter (D90 size) in the range of 1 nano meter to 10 microns. In an alternative embodiment of the invention, the micro silica for coating on the fine aggregate preferably has a diameter in the range of 1 nano meter to 1 micron. In an alternative embodiment of the invention, the micro silica for coating on the coarse aggregate preferably has a diameter in the range of 1 nano meter to 0.1 microns. In still another alternative embodiment of the invention, the micro silica for coating on the coarse aggregate has a diameter in the range of 10 nano meter to 10 microns. In a further alternative embodiment of the invention, the micro silica for coating on the coarse aggregate has a diameter in the range of 20 nano meter to 1 micron. In a further alternative embodiment of the invention, the micro silica for coating on the coarse aggregate has a diameter in the range of 50 nano meter to 1 micron. In a further alternative embodiment of the invention, the micro silica for coating on the coarse aggregate has a diameter in the range of 75 nano meter to 1 micron. In a further alternative embodiment of the invention, the micro silica for coating on the coarse aggregate has a diameter in the range of 100 nano meter to 2.5 microns. In a further alternative embodiment of the invention, the micro silica for coating on the coarse aggregate has a diameter in the range of 150 nano meter to 500 nano meter.

[069] In a furthermore embodiment of the invention, the micro silica for coating on the coarse aggregate is in the range of 0.1 to 5.0 wt.% of the coarse aggregate. In an alternative embodiment of the invention, the micro silica for coating on the coarse aggregate is in the range of 0.1 to 3.0 wt.% of the coarse aggregate. In still another alternative embodiment of the invention, the micro silica for coating on the coarse aggregate is in the range of 0.1 to 2.0 wt.% of the coarse aggregate. In a further alternative embodiment of the invention, the micro silica for coating on the coarse aggregate is in the range of 0.1 to 1.0 wt.% of the coarse aggregate. In a further alternative embodiment of the invention, the micro silica for coating on the coarse aggregate is in the range of 0.5 to 2.0 wt.% of the coarse aggregate. In a further alternative embodiment of the invention, the micro silica for coating on the coarse aggregate is in the range of 0.5 to 1.0 wt.% of the coarse aggregate.

[070] In an embodiment of the invention, the fine aggregate further comprises activated calcium hydroxide. The activated calcium hydroxide can may be present in an amount in the range of 0.1 to 15.0 wt.% of the fine aggregate. The activated calcium hydroxide can may be present in an amount in the range of 0.1 to 10.0 wt.% of the fine aggregate. The activated calcium hydroxide can may be present in an amount in the range of 0.1 to 5.0 wt.% of the fine aggregate. The activated calcium hydroxide can may be present in an amount in the range of 1.0 to 5.0 wt.% of the fine aggregate. In an embodiment of the invention, activated calcium hydroxide may be separately added to the fine aggregate having the layer of micro silica. In another embodiment of the invention the activated calcium hydroxide may be in-situ generated while making the fine aggregate having the layer of micro silica there-upon as will be described in detail in later paragraphs.

[071] In another embodiment of the invention, the first part may comprise the one or more additive in an amount up to 5 wt.% of the composition. In another embodiment of the invention, the first part may comprise the one or more additive in an amount up to 4 wt.% of the composition. In another embodiment of the invention, the first part may comprise the one or more additive in an amount up to 2.5 wt.% of the composition. In another embodiment of the invention, the first part may comprise the one or more additive in an amount up to 1 wt.% of the composition.

[072] In yet another embodiment of the invention, when the composition is in two-part form, the second part comprises the binder material and optionally at least one additive. In another embodiment of the invention, the second part may comprise the one or more additive in an amount up to 5 wt.% of the composition. In another embodiment of the invention, the second part may comprise the one or more additive in an amount up to 4 wt.% of the composition. In another embodiment of the invention, the second part may comprise the one or more additive in an amount up to 2.5 wt.% of the composition. In another embodiment of the invention, the second part may comprise the one or more additive in an amount up to 1 wt.% of the composition.

[073] In still another embodiment of the invention, when the composition is in three-part form; the first part comprises coarse aggregate optionally comprising a layer of micro silica thereupon and the fine aggregate comprising a layer of micro silica thereupon, the second part comprises the binder material, and the third part comprises the at least one additive.

[074] In a further embodiment of the invention, the binder material comprises the binder material comprises a first material selected from a group comprising of Portland cement, modified Portland cement, or masonry cement, hydraulic hydrated lime, white cement, calcium aluminate cement, silicate cement, phosphate cement, high-alumina cement, magnesium oxychloride cement, oil well cements, and combinations thereof.

[075] In a furthermore embodiment of the invention, the binder material may optionally comprise a second material selected from a group comprising of blast furnace slag (including Ground Granulated Blast Furnace Slag (GGBS)), chemically modified blast furnace slag, Lightweight Expanded Clay Aggregate (LECA), Calcined Clay (Meta star), Red Brick Dust (RBD), Tile and Yellow Brick Dust (YBD) and combinations thereof. In case the binder material comprises a combination of the first material as stated above and the second material as stated above, the first material may be present in an amount in the range of 20 to 90 wt% of the binder material and the second material constitutes a remaining amount of the binder material.

[076] In an embodiment of the invention, the binder material may optionally comprise a third material selected from a group comprising of fly ash, chemically modified fly ash, Pulverized Fuel Ash (PFA), Rice Husk Ash (RHA), volcanic ash material, finely ground quartz material, chemically modified quartz, pond ash, and combination thereof. In case the binder material comprises a combination of the first material as stated above and the third material as stated above, the first material may be present in an amount in the range of 50 to 90 wt% of the binder material and the third material constitutes a remaining amount of the binder material. In case the binder material comprises a combination of the first material as stated above, the second material as stated above, and the third material as stated above, the first material may be present in an amount in the range of 20 to 60 wt% of the binder material, the second material may be present in an amount in the range of 20 to 50 wt% of the binder material, and the third material constitutes a remaining amount of the binder material.

[077] In another embodiment of the invention, the binder material may optionally comprise a fourth material selected from a group comprising sodium sulphate, micro silica, lime, and combination thereof. It may be noted that the binder material may comprise the fourth material when the binder material already comprises the third material. In case the binder material comprises a combination of the first material as stated above, the third material as stated above, and the fourth material as stated above, the first material may be present in an amount in the range of 20 to 60 wt% of the binder material, the third material may be present in an amount in the range of 20 to 50 wt% of the binder material, and the fourth material constitutes a remaining amount of the binder material. In case the binder material comprises a combination of the first material as stated above, the second material as stated above, the third material as stated above, and the fourth material as stated above, the first material may be present in an amount in the range of 20 to 60 wt% of the binder material, the second material may be present in an amount in the range of 20 to 50 wt% of the binder material, the third material may be present in an amount in the range of 20 to 50 wt% of the binder material, and the fourth material constitutes a remaining amount of the binder material. The fourth material is generally present up to a maximum of 10 wt% of the binder material.

[078] In yet another embodiment of the invention, the binder material may comprise two or more fractions that are different from each other in term of their D90 size or in terms of their mode average particle size (MAPS).

[079] In still another embodiment of the invention, the binder material comprises:
(a) a first binder size fraction having D90 size or MAPS in the range of 70 to 80 microns;
(b) a second binder size fraction having D90 size or MAPS in the range of 20 to 30 microns;
(c) optionally, a third binder size fraction having D90 size or MAPS in the range of 3 to 8 microns; and
(d) optionally, a fourth binder size fraction having D90 size or MAPS in the range of 0.01 to 2 microns.

[080] In a further embodiment of the invention, the first binder size fraction is present in an amount in a range of 50 to 85 wt.% of the amount of the binder material; the second binder size fraction constitutes a remaining amount of the binder material. In another embodiment of the invention, the first binder size fraction is present in an amount in a range of 50 to 85 wt.% of the amount of the binder material, the second binder size fraction is present in an amount in a range of 20 to 40 wt.% of the amount of the first binder size fraction, and the third binder size fraction constitutes a remaining amount of the binder material. In another embodiment of the invention, the first binder size fraction is present in an amount in a range of 50 to 85 wt.% of the amount of the binder material, the second binder size fraction is present in an amount in a range of 20 to 40 wt.% of the amount of the first binder size fraction, the third binder size fraction is present in an amount in a range of 20 to 40 wt.% of the amount of the second binder size fraction; the fourth binder size fraction constitutes a remaining amount of the binder material.

[081] In a furthermore embodiment of the invention, the first material forming part of the binder material has a single size fraction having D90 size or MAPS in the range of 70 to 80 microns.

[082] In an embodiment of the invention, the first material forming part of the binder material comprises: a first material first size fraction having D90 size or MAPS in the range of 70 to 80 microns; a first material second size fraction having D90 size or MAPS in the range of 20 to 30 microns; and optionally a first material third size fraction having D90 size or MAPS in the range of 3 to 8 microns.

[083] In case the first material forming part of the binder material comprises the first material first size fraction as mentioned above and the first material second size fraction as mentioned above; the first material first size fraction is present an amount in a range of 50 to 85 wt.% of the amount of the first material and the first material second size fraction constitutes a remaining amount of the first material. In case the first material forming part of the binder material comprises the first material first size fraction as mentioned above, the first material second size fraction as mentioned above, and the first material third size fraction as mentioned above; the first material first size fraction is present an amount in a range of 50 to 85 wt.% of the amount of the first material, the first material second size fraction is present an amount in a range of 20 to 40 wt.% of the amount of the first material first size fraction, and the first material third size fraction constituting a remaining amount of the first material.

[084] In yet another embodiment of the invention, the second material forming part of the binder material comprises: a second material first size fraction having D90 size or MAPS in the range of 70 to 80 microns; a second material second size fraction having D90 size or MAPS in the range of 20 to 30 microns; optionally, a second material third size fraction having D90 size or MAPS in the range of 3 to 8 microns; and optionally, a second material fourth size fraction having D90 size or MAPS in the range of 0.01 to 2 microns.

[085] In case the second material forming part of the binder material comprises the second material first size fraction as mentioned above and the second material second size fraction as mentioned above; the second material first size fraction is present an amount in a range of 50 to 85 wt.% of the amount of the second material and the second material second size fraction constitutes a remaining amount of the second material.

[086] In case the second material forming part of the binder material comprises the second material first size fraction as mentioned above, the second material second size fraction as mentioned above, and the second material third size fraction as mentioned above; the second material first size fraction is present an amount in a range of 50 to 85 wt.% of the amount of the second material, the second material second size fraction is present an amount in a range of 20 to 40 wt.% of the amount of the second material first size fraction, and the second material third size fraction constitutes a remaining amount of the second material.

[087] In case the second material forming part of the binder material comprises the second material first size fraction as mentioned above, the second material second size fraction as mentioned above, the second material third size fraction as mentioned above, and the second material fourth size fraction as mentioned above; the second material first size fraction is present an amount in a range of 50 to 85 wt.% of the amount of the second material, the second material second size fraction is present an amount in a range of 20 to 40 wt.% of the amount of the second material first size fraction, the second material third size fraction is present an amount in a range of 20 to 40 wt.% of the amount of the second material second size fraction, and the second material fourth size fraction constitutes a remaining amount of the second material.

[088] In still another embodiment of the invention, the third material forming part of the binder material comprises: a third material first size fraction having D90 size or MAPS in the range of 70 to 80 microns; a third material second size fraction having D90 size or MAPS in the range of 20 to 30 microns; optionally, a third material third size fraction having D90 size or MAPS in the range of 3 to 8 microns; and optionally, a third material fourth size fraction having D90 size or MAPS in the range of 0.01 to 2 microns.

[089] In case the third material forming part of the binder material comprises the third material first size fraction as mentioned above and the third material second size fraction as mentioned above; the third material first size fraction is present an amount in a range of 50 to 85 wt.% of the amount of the third material and the third material second size fraction constitutes a remaining amount of the third material.

[090] In case the third material forming part of the binder material comprises the third material first size fraction as mentioned above, the third material second size fraction as mentioned above, and the third material third size fraction as mentioned above; the third material first size fraction is present an amount in a range of 50 to 85 wt.% of the amount of the third material, the third material second size fraction is present an amount in a range of 20 to 40 wt.% of the amount of the third material first size fraction, and the third material third size fraction constitutes a remaining amount of the third material.

[091] In case the third material forming part of the binder material comprises the third material first size fraction as mentioned above, the third material second size fraction as mentioned above, the third material third size fraction as mentioned above, and the third material fourth size fraction as mentioned above; the third material first size fraction is present an amount in a range of 50 to 85 wt.% of the amount of the third material, the third material second size fraction is present an amount in a range of 20 to 40 wt.% of the amount of the third material first size fraction, the third material third size fraction is present an amount in a range of 20 to 40 wt.% of the amount of the third material second size fraction, and the third material fourth size fraction constitutes a remaining amount of the third material.

[092] In still another embodiment of the invention, the fourth material forming part of the binder material comprises at least one of a fourth material first size fraction having D90 size or MAPS in the range of 3 to 8 microns and a fourth material second size fraction having D90 size or MAPS in the range of 0.01 to 2 microns. In case the fourth material forming part of the binder material comprises the fourth material first size fraction as mentioned above and the fourth material second size fraction as mentioned above, the same may be present in equal quantities.

[093] The binder the having the aforesaid characteristics, is a highly dense and compact binder and follows the optimized packaging concept. Also, the binder having the aforesaid characteristics better utilizes the second material and the third material and tends to reduce a quantity of the first material used for making the binder. The binder having the aforesaid characteristics shows enhancement of early strength characteristics despite use of a substantial quantity of the second material and the third material. The binder having the aforesaid characteristics, have a continuous series of different mode average particle sizes providing a complete packing of the particle lattice structure ranging from Macro-Micro-Nano level. Thus, the binder provides a perfect particle chemistry to fill the maximum voids of the binder lattice structure and also improves concrete chemistry related to the early settings and the latter settings of the concrete structure.

[094] Now coming to the aspect of the additives, the composition comprises at least one additive selected from a group comprising of Melamine, Lignosulphonate, Sulphonated Naphthalene Formaldehyde, Sulphonated melamine formaldehyde, Polycarboxylate based compound, carbon nanotube (CNT) based additives, sodium hydroxide, potassium hydroxide, magnesium hydroxide and combinations thereof. The at least one additive may be present in an amount up to 5 wt.% of the composition.

[095] In another embodiment, the composition may optionally include fibers in amounts ranging from 1 to 5 wt.% of the total composition. These fibers can vary in material, and may be made of steel, polymer, glass, asbestos, carbon, or organic material. The fibers are typically in the length range of 5 mm to 50 mm, allowing them to provide reinforcement within the concrete, improving its tensile strength and crack resistance.

[096] In yet another embodiment of the invention, the fibers may be made of materials such as polyethylene, polypropylene, polyester, or steel, with a tensile strength ranging from 300 N/mm² to 2000 N/mm². The fibers enable the concrete structure to be tailored for various applications requiring different levels of strength and durability.

[097] In still another embodiment of the invention, the fibers may have solid or hollow structures. In case the fibers are Solid fibers, the same have an external diameter in the range of 1 to 5 mm, contributing to the structural integrity of the concrete structure. Alternatively, in case the fibers are hollow fibers, the same have an external diameter ranging from 1.1 to 6 mm and have an external diameter in the range of 1 to 5 mm. The hollow fibers may provide additional performance benefits, such as reducing weight or enhancing the mix's flexibility, impact resistance of the concrete structure, earthquake resistance of the concrete structure and flexural toughness performance of the concrete structure. In yet another alternative embodiment of the invention, the fibres are hollow and have their ends closed and is filled with air or with a fluid. In an embodiment of the invention, the fluid is non-reactive to the fibres. In another embodiment of the invention, the fluid has a viscosity index in the range of 100 to 250 N·s/m2. Non-limiting example of the fluid include food grade oils, and other synthetic oils.

[098] In another embodiment of the invention, the fibres are having a layer of micro silica thereupon, an amount of micro silica being in the range of 0.1 to 5.0 wt. % of the fibres. In accordance with an embodiment of the invention, the micro silica has a diameter in the range of 1 nano meter to 10 microns.

[099] Now coming to the process for making the composition, the process comprises obtaining coarse aggregates optionally comprising a layer of micro silica thereupon; obtaining fine aggregates comprising a layer of micro silica thereupon, an amount of micro silica being in the range of 0.1 to 5.0 wt.% of the fine aggregate; and mixing the coarse aggregate thus obtained with the fine aggregate thus obtained such that the coarse aggregates optionally comprising the layer of micro silica is in an amount of 20 to 50 wt.% of the composition, and the fine aggregates comprising the layer of micro silica thereupon is present in an amount of 15 to 45 wt.% of the composition. The method further comprises providing a binder material in an amount of 10 to 25 wt.% of the composition; and optionally providing at least one additive the at least one additive being present in an amount of 0 to 5 wt.% of the composition.

[0100] In an embodiment of the invention during the process of making the composition, a rate of moisture absorption of a raw material (such as coarse aggregate or fine aggregate or binder or the additive) is determined, the rate of moisture absorption being dependent upon a prevailing environment condition; and controlling, based on the rate of moisture absorption thus determined, at least one parameter pertaining to preparing and packaging of composition, the wherein the at least one parameter comprises a total time period for preparing the composition, a need to heat the raw material or the composition (after the same has been prepared), the amount of heat needed to be provided, etc. More details of such process are provided in Applicant’s earlier patent application number 201831019418.

[0101] As stated above in an embodiment of the invention, the composition may be in one-part form or may be in two-part form or in three-part form. In case the composition is in one-part form, the binder material and optionally the at least one additive are mixed with the coarse aggregates optionally comprising a layer of micro silica thereupon and the fine aggregates comprising a layer of micro silica thereupon. In case the composition is in two-part form, the coarse aggregates optionally comprising a layer of micro silica thereupon and the fine aggregates comprising a layer of micro silica thereupon and optionally the at least one additive are mixed to form the first part while the binder material and optionally the at least one additive are mixed to form the second part and both parts are provided separately to be mixed at the time of forming the wet concrete mass. In case the composition is in three-part form, the coarse aggregates optionally comprising a layer of micro silica thereupon and the fine aggregates comprising a layer of micro silica thereupon are mixed to form the first part while the binder material is provided as the second part and the at least one additive is provided as the third part to be mixed at the time of forming the wet concrete mass.

[0102] Now coming to obtaining the fine aggregate having a layer of micro silica thereupon, the same can be prepared by multiple ways. Some of the non-limiting processes for preparing the fine aggregate having a layer of micro silica thereupon are provided herein-below.

[0103] In a first process for preparing the fine aggregate having a layer of micro silica thereupon, wet fine aggregate is bought in contact with solid micro silica to obtain wet coated fine aggregate. Thereafter, the wet coated fine aggregate is dried to obtain the fine aggregate having a layer of micro silica thereupon. In this case, the amount of micro silica, and the amount of water used are being such that the fine aggregate comprises 0.1 to 5.0 wt.% of micro silica layer thereupon, the weight percentage being based on a weight of the fine aggregate.

[0104] In a second process for preparing the fine aggregate having a layer of micro silica thereupon, fine aggregate, calcium carbide, water and micro silica are mixed (in any sequence) to obtain a wet coated fine aggregate. When calcium carbide comes in contact with water, it produces acetylene gas and calcium hydroxide. Without removing the acetylene gas, the wet coated fine aggregate is ignited which leads to burning of the acetylene gas and drying of the wet coated fine aggregate to obtain a mixture comprising activated calcium hydroxide and fine aggregate having a layer of micro silica thereupon. Once again in this case, the amount of micro silica, and the amount of water being such that the fine aggregate comprises 0.1 to 5.0 wt.% of micro silica layer thereupon, the weight percentage being based on a weight of the fine aggregate. It may be noted that in this process, the amount of calcium carbide added may be sufficient to produce calcium hydroxide in an amount in the range of 0.1 to 15.0 wt.% of the fine aggregate. When the acetylene gas is ignited, a temperature of 500 to 700o C is attained which results in activation of the calcium hydroxide to produce activated calcium hydroxide. Thus, this process in-situ produces fine aggregate having the layer of micro silica there-upon and having activated calcium hydroxide. Mixed in the fine aggregate, ready to react with pozzolans at initial stages itself, when the concrete is still in the plastic phase, along with C3A hydration, thus creating phenomenal early strengths and density of matrix. This reduces the need of hydraulic material too.

[0105] Now coming to obtaining the coarse aggregate having a layer of micro silica thereupon, the same can be prepared by multiple ways. Some of the non-limiting processes for preparing the coarse aggregate having a layer of micro silica thereupon are provided herein-below.

[0106] In a first process for preparing the coarse aggregate having a layer of micro silica thereupon, a slurry of micro-silica in water is prepared and the same is sprayed on coarse aggregate to obtained wet coarse aggregate. Thereafter, the wet coarse aggregate is dried to obtain coarse aggregate having a layer of micro silica thereupon.

[0107] In a second process for preparing the coarse aggregate having a layer of micro silica thereupon, water is sprayed on to the coarse aggregate to obtain wet coarse aggregate. The wet coarse aggregate is then brought in contact with micro silica powders which leads to obtaining wet coarse aggregate having a layer of micro silica thereupon. Thereafter, the wet coarse aggregate having a layer of micro silica thereupon is dried by supplying external heat. Compared to the first process, the second process is advantageously placed as the amount of water needed may be reduced and a more uniform thin coating of micro silica is obtained by following the second process, compared to the first process. This would also lead to reducing an amount of energy spent to obtain the coarse aggregate having a layer of micro silica thereupon.

[0108] Now coming to the process of obtaining the binder material, the same can be prepared by multiple ways including the way described in Applicant’s previous Indian Patent Application number 201631027942, 201731024816, 201731020956, 201731027025, 201731032483, 201831022452, 201831019418, 201932006254, 202031031282, 202131020255, and 202231045976, the contents of which are incorporated herein in their entirety.

[0109] By way of a non-limiting example, if the binder material comprises solely the first material and more particularly comprises only one of Portland cement, modified Portland cement, hydraulic hydrated lime, white cement, calcium aluminate cement, silicate cement, phosphate cement, high-alumina cement, magnesium oxychloride cement, oil well cements, the same can be procured from commercial sources. The first material may have any suitable strength and any suitable size in terms of MAPS. By way of another non-limiting example, if the binder material comprises solely the first material but comprises a combination of two or more of Portland cement, modified Portland cement, hydraulic hydrated lime, white cement, calcium aluminate cement, silicate cement, phosphate cement, high-alumina cement, magnesium oxychloride cement, oil well cements, then the suitable material can be procured from commercial sources and mixed in the desired ratio.

[0110] By way of another non-limiting example, if the binder material comprises solely the first material, and one or more of the second material, the third material, the fourth material, then each of the first material and one or more of the second material, the third material, the fourth material and suitably mixed in the desired proportion to obtain the binder material. It may be noted that prior to mixing the first material, and one or more of the second material, the third material, the fourth material, it is possible to classify each of the first material, and one or more of the second material, the third material, the fourth material into one or more sub-classes and then mix the suitable sub-classes in the desired proportion to obtain the binder material.

[0111] Now coming to the aspect of preparing the process for preparing the wet concrete mixture, the same comprises mixing the composition comprising coarse aggregates in an amount of 20 to 50 wt.% of the composition, fine aggregates in an amount of 15 to 45 wt.% of the composition, and optionally binder material in an amount of 10 to 25 wt.% of the composition; and optionally at least one additive in an amount of 0 to 5 wt.% of the composition, the coarse aggregate optionally comprising a layer of micro silica thereupon; and the fine aggregate comprising a layer of micro silica thereupon, an amount of micro silica being in the range of 0.1 to 5.0 wt.% of the fine aggregate with water in an amount of 4 to 8 wt.% of the composition to obtain the wet concrete mass.

[0112] In case the composition is in one-part form, the process involves a traditional process of mixing all the ingredients in the composition and then adding water in an amount of 4 to 8 wt.% of the composition to obtain the wet concrete mass.

[0113] In case the composition is in two-part form as mentioned above, it is preferable to mix the second part comprising the binder material and optionally the at least one additive with water to obtain a first slurry; and thereafter mixing the first part comprising the coarse aggregates, optionally comprising a layer of micro silica thereupon, the fine aggregates comprising the layer of micro silica thereupon and optionally the at least one additive with the first slurry in any sequence to obtain the wet concrete mass.

[0114] In case the composition is in three-part form as mentioned above, it is preferable to mix the at least one additive with water to obtain an aqueous solution, mix the second part comprising the binder material and optionally the at least one additive with the aqueous solution to the obtain a first slurry; and thereafter mixing the first part comprising the coarse aggregates, optionally comprising a layer of micro silica thereupon, the fine aggregates comprising the layer of micro silica thereupon and optionally the at least one additive with the first slurry in any sequence to obtain the wet concrete mass.

[0115] To better understand the working of the invention and the advantages of the invention, reference is drawn to the following examples. It may be noted that one or more of the following tests have been performed to understand the working of the invention and the advantages of the invention.

[0116] Slump test: Cone slump test of different mixes was carried out as per IS:1199. The mold was placed on a levelled metal plate. The concrete mix was then filled in three layers, each approximately one-third of the height of the mold, and tamped with twenty-five strokes with a tamping rod. The mold was removed from the concrete immediately by raising it slowly in the vertical direction. This allowed the concrete to subside and the slump was measured.

[0117] Compressive strength: Concrete cubes of size 150 x 150 x 150 mm were tested for their compressive strength on a 1000 kN capacity compression testing machine. The load was steadily and uniformly applied, starting from zero at a rate of 0.25 mm/min as per IS:516-2021. Three cubes were tested to represent the compressive strength of that particular batch. Cube specimens have been tested in the machine in such a manner that the loads are applied to the opposite sides of the cubes as cast. The test has been carried out at the ages of 1, 3, 7, and 28 days. Also, in some cases, the specimens are air cured for 7 and 28 days to check the self-curing property.

[0118] Flexural strength: The modulus of rupture of the concrete specimens (100 x 100 x 500 mm) was tested on a Universal testing machine of 400 kN capacity in accordance with IS:516-1959 (Reaffirmed 2018). The bed of the testing machine was provided with two steel rollers, 38 mm in diameter, on which the specimen was supported, and these rollers were so mounted that the distance from center to center was 400 mm. The load was applied through two similar rollers mounted at the third point of the supporting span that is, spaced at 133.3 mm center to center.
The Modulus of rupture is calculated as:
fb = pl/bd2
where,
p - maximum load applied to the specimen, N
l - length of the span on which the specimen was supported, mm
b - measured width of the specimen, mm
d – cross-sectional dimension of the specimen, mm.

[0119] Splitting tensile strength: Splitting tensile strength test is the indirect measurement of the tensile strength of concrete by the application of compressive load. Cylindrical specimens of sizes 150 mm diameter and 300 mm height were tested on a compression testing machine (2000 kN capacity) according to IS:5816-1999 to measure the splitting tensile strength of concrete. The specimens were placed horizontally between the platens of the CTM along with two packing strips of 15 mm width and 4 mm thickness. All the cylinders have been subjected to the action of compressive force along two opposite edges. By applying the force in this manner, the cylinder is subjected to compression near the loaded region, and the length of the cylinder is subjected to uniform tensile stress. The maximum load applied is recorded as P. The measured splitting tensile strength of the specimen is calculated as

fct = 2P/π l d
where,
P - maximum load applied, N
l - length of the specimen, mm
d - cross-sectional dimension of the specimen, mm.

[0120] Water permeability test: The water permeability test of the concrete specimens was carried out according to DIN 1048-Part 5 at a constant water pressure of 5 bars for 72 hrs. At the end of the test, the 150 x 150 x 150 mm cube samples were split into two halves and the depth of the water penetration inside the samples were measured.

[0121] Rapid chloride permeability test (RCPT): Rapid chloride ion penetration test was carried out according to ASTM C 1202. The core of size ~95 mm dia by ~50 mm thickness was cast. The test was run at standard 60V DC for 6 hrs. The total charge passed in Coulombs in the samples was recorded.

[0122] Abrasion resistance: A Cantabro abrasion resistance test on concrete was carried out using ASTM C1747 (2015). The test method measures the percentage abrasion loss of samples subjected to frequent rubbing and skidding using the Los Angeles abrasion machine. The results obtained were compared with those of control concrete (M1).

[0123] Bond Strength between concrete and Reinforcing steel: The bond strength between concrete and Reinforcing steel - Fe 500 or Fe 1650, as the case may be at 28 days is measured in megapascals (MPa) using the pull-out test. This test is performed in accordance with the Indian Standard IS 2770.

[0124] Average Residual Strength: Average residual strength was determined as per ASTM C-1399.

[0125] Characteristics of the Coarse aggregate used for the Examples: Coarse aggregate of 20 mm down size IS Sieve Designation (mm) and coarse aggregate of 12.5 mm down size were mixed in 70:30 ratio (hereinafter referred to as un-coated coarse aggregate) was used in some examples. In some cases, the coarse aggregate having the aforesaid dimensions and aforesaid ratio was coated with micro-silica in an amount as specified in the respective example and the same is referred to as Coated Coarse Aggregate.

[0126] Characteristics of the Fine aggregate used for the Examples: Manufactured sand confirming to Zone 2 as per the requirements of IS 383:2016 was used in this study as fine aggregate. The sieve analysis of the fine aggregate is given in Table 3.

Table 3: Characteristics of the Fine aggregate

IS Sieve Designation Cumulative Percent Specification as per IS:383-2016 in respect of 20 mm nominal size aggregate
(% passing)
Retained (%) Passing (%) Zone I Zone II Zone III
4.75 mm 0 100 90-100 90-100 90-100
2.36 mm 17.5 82.8 60-95 75-100 85-100
1.18 mm 19.1 63.4 30-70 55-90 75-100
600 μm 17 40.4 15-34 35-59 60-79
300 μm 15 31.4 5-20 8-30 12-40
150 μm 13.3 18.1 0-10 0-10 0-10
Pan 18.1 0
REMARKS: Sample conforms to the requirement of single size aggregate as per IS:383-2016.

[0127] The manufactured sand confirms to the requirements of IS:383-2016 and the same was used either with or without micro-silica layer coated thereupon. In case of the fine aggregate is coated, the amount of micro silica used for coating is specified in the respective example and the same is referred to as Coated Fine Aggregate.

Example 1:
[0128] A wet concrete mix was manufactured using a pan mixer with a rotating drum and fixed blade. Binder, coarse aggregates, fine aggregates, and at least one additive as per Table 4 are mixed for 2-3 minutes. Thereafter, water in an amount to maintain a water-binder ratio of 0.22 was added and the whole mixture is mixed for 5 to 6 minutes until a homogenous mix is obtained. The resulting mixes were filled in appropriate molds (relevant for different experiments as per Indian Standards) having the suitable sizes (as per the test to be performed, details of which have been provided above). The completely filled molds were subjected to vibration on the vibrating table until all entrapped air was expelled. Samples were cured in water for 28 days after demolding and stored in a curing tank maintaining temperature conditions as per Indian Standard IS 456-2000.

Table 4: Compositional Details of the Concrete and the Results
Ingredients Mix 1 Mix 2 Mix 3 Mix 4
(Weights in KGS or in wt%)
Binder – OPC 53 grade 500 500 500 500
Uncoated coarse Aggregate 1206 - 1206 -
Coated Coarse Aggregate (containing micro silica in an amount equal to 1% by weight of coarse aggregate i.e. 12 kg) - 1218 - 1218
Uncoated Fine Aggregate 740 740 - -
Micro silica added separately 27 15 12 0
Weight % of Poly Carbonate Based Additive added based on weight of Binder + micro silica (if added separately) 1.5% 1.5% 1.5% 1.5%
Coated Fine Aggregate (containing micro silica in an amount equal to about 2% by weight of fine aggregate i.e. 15kg of micro silica) - - 755 755
Compressive Strength (in MPa)
1 day 19.9 21.2 22.8 23.7
3 days 46.2 47.0 49.8 50.5
7 days 65.2 67.2 68.4 70.1
28 days 99.2 100.2 103.4 105.6
Slump at ‘0’ minutes (mm) >200 mm >200 mm >200 mm >200 mm
Slump after 1 hour (mm) 70 mm 70 mm 80 mm 80 mm
Flexural Strength at 28 days (Mpa) 5.8 6.1 6.9 7.3
Splitting Tensile Strength at 28 days (Mpa) 2.5 2.6 2.8 2.8
Abrasion loss (%) 14.2 14.0 13.6 13.0
Water Permeability (mm) 36 mm 35 mm 32 mm 28 mm
RCPT value (Coulombs) after 6 hours 2956 2870 2850 2700
Compressive Strength at 7 days (Self Cured) 39.2 38.0 38.0 43.4
Compressive strength at 28 days (Self Cured) 69.8 72.0 73.7 78.2
Bond strength between concrete and Fe 500 steel (Mpa) at 28 days 4.2 4.3 4.6 4.7
Bond strength between concrete and Prestressing steel (Fe 1650) at 28 days 4.1 4.2 4.8 5.0
Shear strength of concrete at 28 days (Mpa) 2.1 2.2 2.2 2.3

Example 2:
[0129] A wet concrete mix was manufactured using a pan mixer with a rotating drum and fixed blade. Binder, at least one additive and water in an amount to maintain a water-binder ratio of 0.22 were mixed to obtain a slurry. Thereafter, coarse aggregates and fine aggregates as per Table 5 are added and the whole mixture is mixed for 5-6 minutes until a homogenous mix is obtained. The resulting mixes were filled in appropriate molds having the suitable sizes (as per the test to be performed, details of which have been provided above). The completely filled molds were subjected to vibration on the vibrating table until all entrapped air was expelled. Samples were cured in water for 28 days after demolding and stored in a curing tank maintaining temperature conditions as per Indian Standard IS 456-2000.

Table 5: Compositional Details of the Concrete and the Results
Ingredients Mix 5 Mix 6 Mix 7 Mix 8
(Weights in KGS or in wt%)
Binder – OPC 53 grade 500 500 500 500
Uncoated coarse Aggregate 1206 - 1206 -
Coated Coarse Aggregate (containing micro silica in an amount equal to 1% by weight of coarse aggregate i.e. 12 kg) - 1218 - 1218
Uncoated Fine Aggregate 740 740 - -
Micro silica added separately 27 15 12 0
Weight % of Poly Carbonate Based Additive added based on weight of Binder + micro silica (if added separately) 1.5% 1.5% 1.5% 1.5%
Coated Fine Aggregate (containing micro silica in an amount equal to about 2% by weight of fine aggregate i.e. 15kg of micro silica) - - 755 755
Compressive Strength (in MPa)
1 day 23.5 24.6 26.6 27.9
3 days 48.4 50.0 53.2 54.8
7 days 67.8 70.3 74.2 75.9
28 days 99.8 102.2 106.3 110.0
Slump at ‘0’ minutes (mm) >200 mm >200 mm >200 mm >200 mm
Slump after 1 hour (mm) 70 mm 80 mm 80 mm 90 mm
Flexural Strength at 28 days (Mpa) 5.8 6.3 7.2 7.5
Splitting Tensile Strength at 28 days (Mpa) 2.6 2.6 2.9 3.0
Abrasion loss (%) 14.0 14.0 13.2 12.7
Water Permeability (mm) 30 mm 30 mm 27 mm 27 mm
RCPT value (Coulombs) after 6 hours 2850 2770 2746 2650
Compressive Strength at 7 days (Self Cured) 60.2 65.5 63.8 70.2
Compressive strength at 28 days (Self Cured) 89.8 95.0 97.3 99.8
Bond strength between concrete and Fe 500 steel (Mpa) at 28 days 4.4 4.8 4.9 5.3
Bond strength between concrete and Prestressing steel (Fe 1650) at 28 days 4.8 5.2 6.1 6.8
Shear strength of concrete at 28 days (Mpa) 2.5 2.5 2.7 2.9

Example 3:
[0130] A wet concrete mix was manufactured using a pan mixer with a rotating drum and fixed blade. Binder which is a mix of OPC 53 grade cement and fly ash in a ratio of 70:30, coarse aggregates, fine aggregates, and at least one additive as per Table 6 are mixed for 2-3 minutes. Thereafter, water in an amount to maintain a water-binder ratio of 0.22 was added and the whole mixture is mixed for 5-6 minutes until a homogenoumix is obtained. The resulting mixes were filled in appropriate molds (relevant for different experiments as per Indian Standards) having the suitable sizes (as per the test to be performed, details of which have been provided above). The completely filled molds were subjected to vibration on the vibrating table until all entrapped air was expelled. Samples were cured in water for 28 days after demolding and stored in a curing tank maintaining temperature conditions as per Indian Standard IS 456-2000.

Table 6: Compositional Details of the Concrete and the Results
Ingredients Mix 9 Mix 10 Mix 11 Mix 12
(Weights in KGS or in wt%)
Binder – OPC 53 grade + Fly ash 500 500 500 500
Uncoated coarse Aggregate 1206 - 1206 -
Coated Coarse Aggregate (containing micro silica in an amount equal to 1% by weight of coarse aggregate i.e. 12 kg) - 1218 - 1218
Uncoated Fine Aggregate 740 740 - -
Micro silica added separately 27 15 12 0
Weight % of Poly Carbonate Based Additive added based on weight of Binder + micro silica (if added separately) 1.5% 1.5% 1.5% 1.5%
Coated Fine Aggregate (containing micro silica in an amount equal to about 2% by weight of fine aggregate i.e. 15kg of micro silica) - - 755 755
Compressive Strength (in MPa)
1 day 26.8 28.1 30.2 33.8
3 days 47.2 49.2 52.3 55.0
7 days 68.8 72.1 74.0 76.2
28 days 100.2 102.8 109.2 112.6
Slump at ‘0’ minutes (mm) >200 mm >200 mm >200 mm >200 mm
Slump after 1 hour (mm) 60 mm 80 mm 90 mm 100 mm
Flexural Strength at 28 days (Mpa) 5.7 6.4 7.4 7.8
Splitting Tensile Strength at 28 days (Mpa) 2.7 2.7 2.9 3.4
Abrasion loss (%) 13.2 13.0 13.0 12.2
Water Permeability (mm) 25 mm 25 mm 22 mm 22 mm
RCPT value (Coulombs) after 6 hours 1850 1763 1750 1700
Compressive Strength at 7 days (Self Cured) 62.3 62.8 65.8 72.6
Compressive strength at 28 days (Self Cured) 94.2 97.3 102.7 104.0
Bond strength between concrete and Fe 500 steel (Mpa) at 28 days 4.3 4.8 4.9 5.5
Bond strength between concrete and Prestressing steel (Fe 1650) at 28 days 5.1 5.2 6.8 7.7
Shear strength of concrete at 28 days (Mpa) 3.0 2.9 3.3 3.9

Example 4:
[0131] A wet concrete mix was manufactured using a pan mixer with a rotating drum and fixed blade. Binder which is a mix of OPC 53 grade cement and fly ash in a ratio of 70:30, at least one additive and water in an amount to maintain a water-binder ratio of 0.22 were mixed to obtain a slurry. Thereafter, coarse aggregates and fine aggregates as per Table 7 are added and the whole mixture is mixed for 5-6 minutes until a homogenous mix is obtained. The resulting mixes were filled in appropriate molds (relevant for different experiments as per Indian Standards) having the suitable sizes (as per the test to be performed, details of which have been provided above). The completely filled molds were subjected to vibration on the vibrating table until all entrapped air was expelled. Samples were cured in water for 28 days after demolding and stored in a curing tank maintaining temperature conditions as per Indian Standard IS 456-2000.

Table 7: Compositional Details of the Concrete and the Results
Ingredients Mix 13 Mix 14 Mix 15 Mix 16
(Weights in KGS or in wt%)
Binder – OPC 53 grade + Fly ash 500 500 500 500
Uncoated coarse Aggregate 1206 - 1206 -
Coated Coarse Aggregate (containing micro silica in an amount equal to 1% by weight of coarse aggregate i.e. 12 kg) - 1218 - 1218
Uncoated Fine Aggregate 740 740 - -
Micro silica added separately 27 15 12 0
Weight % of Poly Carbonate Based Additive added based on weight of Binder + micro silica (if added separately) 1.5% 1.5% 1.5% 1.5%
Coated Fine Aggregate (containing micro silica in an amount equal to about 2% by weight of fine aggregate i.e. 15kg of micro silica) - - 755 755
Compressive Strength (in MPa)
1 day 34.4 37.3 41.0 45.5
3 days 49.1 52.2 53.3 58.2
7 days 71.1 74.2 75.6 78.9
28 days 103.3 105.0 112.7 115.0
Slump at ‘0’ minutes (mm) >200 mm >200 mm >200 mm >200 mm
Slump after 1 hour (mm) 80 mm 100 mm 110 mm 120mm
Flexural Strength at 28 days (Mpa) 6.4 6.6 7.5 8.0
Splitting Tensile Strength at 28 days (Mpa) 2.9 3.0 3.2 3.6
Abrasion loss (%) 12.0 12.0 12.0 11.2
Water Permeability (mm) 20 mm 20 mm 18 mm 18 mm
RCPT value (Coulombs) after 6 hours 1368 1300 1320 1250
Compressive Strength at 7 days (Self Cured) 73.2 74.1 73.9 76.4
Compressive strength at 28 days (Self Cured) 104.5 104.4 109.0 111.1
Bond strength between concrete and Fe 500 steel (Mpa) at 28 days 4.8 5.4 9.0 11.8
Bond strength between concrete and Prestressing steel (Fe 1650) at 28 days 6.6 8.2 10.5 13.2
Shear strength of concrete at 28 days (Mpa) 4.1 4.3 5.9 7.0

Example 5:
[0132] A wet concrete mix was manufactured using a pan mixer with a rotating drum and fixed blade. Binder (which is a mix of OPC 53 grade cement and fly ash in a ratio of 70:30, having a first size fraction having MAPS of 70 to 80 microns and a second size fraction having MAPS of 20 to 30 microns), coarse aggregates, fine aggregates, and at least one additive as per Table 8 are mixed for 2-3 minutes. Thereafter, water in an amount to maintain a water-binder ratio of 0.22 was added and the whole mixture is mixed for 5-6 minutes until a homogenous mix is obtained. The resulting mixes were filled in appropriate molds (relevant for different experiments as per Indian Standards) having the suitable sizes (as per the test to be performed, details of which have been provided above). The completely filled molds were subjected to vibration on the vibrating table until all entrapped air was expelled. Samples were cured in water for 28 days after demolding and stored in a curing tank maintaining temperature conditions as per Indian Standard IS 456-2000.

Table 8: Compositional Details of the Concrete and the Results
Ingredients Mix 17 Mix 18 Mix 19 Mix 20
(Weights in KGS or in wt%)
Binder – OPC 53 grade + Fly ash 500 500 500 500
Uncoated coarse Aggregate 1206 - 1206 -
Coated Coarse Aggregate (containing micro silica in an amount equal to 1% by weight of coarse aggregate i.e. 12 kg) - 1218 - 1218
Uncoated Fine Aggregate 740 740 - -
Micro silica added separately 27 15 12 0
Weight % of Poly Carbonate Based Additive added based on weight of Binder + micro silica (if added separately) 1.5% 1.5% 1.5% 1.5%
Coated Fine Aggregate (containing micro silica in an amount equal to about 2% by weight of fine aggregate i.e. 15kg of micro silica) - - 755 755
Compressive Strength (in MPa)
1 day 38.7 41.0 44.5 49.2
3 days 54.3 57.0 57.2 60.3
7 days 76.5 80.9 84.5 88.0
28 days 109.5 113.3 119.0 122.0
Slump at ‘0’ minutes (mm) >200 mm >200 mm >200 mm >200 mm
Slump after 1 hour (mm) 100 mm 110 mm 140 mm 150mm
Flexural Strength at 28 days (Mpa) 8.4 8.6 9.8 11.2
Splitting Tensile Strength at 28 days (Mpa) 4.2 5.3 7.0 7.9
Abrasion loss (%) 10.0 9.2 8.5 8.0
Water Permeability (mm) 8 mm 8 mm 4 mm 2 mm
RCPT value (Coulombs) after 6 hours 962 880 853 756
Compressive Strength at 7 days (Self Cured) 75.5 78.9 83.5 90.1
Compressive strength at 28 days (Self Cured) 110.2 103.2 118.3 122.7
Bond strength between concrete and Fe 500 steel (Mpa) at 28 days 5.8 7.0 10.2 13.7
Bond strength between concrete and Prestressing steel (Fe 1650) at 28 days 6.0 6.0 13.3 15.0
Shear strength of concrete at 28 days (Mpa) 6.0 6.1 7.0 8.1

Example 6:
[0133] A wet concrete mix was manufactured using a pan mixer with a rotating drum and fixed blade. Binder (which is a mix of OPC 53 grade cement and fly ash in a ratio of 70:30, having a first size fraction having MAPS of 70 to 80 microns and a second size fraction having MAPS of 20 to 30 microns), at least one additive and water in an amount to maintain a water-binder ratio of 0.22 were mixed to obtain a slurry. Thereafter, coarse aggregates and fine aggregates as per Table 9 are added and the whole mixture is mixed for 5-6 minutes until a homogenous mix is obtained. The resulting mixes were filled in appropriate molds (relevant for different experiments as per Indian Standards) having the suitable sizes (as per the test to be performed, details of which have been provided above). The completely filled molds were subjected to vibration on the vibrating table until all entrapped air was expelled. Samples were cured in water for 28 days after demolding and stored in a curing tank maintaining temperature conditions as per Indian Standard IS 456-2000.

Table 9: Compositional Details of the Concrete and the Results
Ingredients Mix 21 Mix 22 Mix 23 Mix 24
(Weights in KGS or in wt%)
Binder – OPC 53 grade + Fly ash 500 500 500 500
Uncoated coarse Aggregate 1206 - 1206 -
Coated Coarse Aggregate (containing micro silica in an amount equal to 1% by weight of coarse aggregate i.e. 12 kg) - 1218 - 1218
Uncoated Fine Aggregate 740 740 - -
Micro silica added separately 27 15 12 0
Weight % of Poly Carbonate Based Additive added based on weight of Binder + micro silica (if added separately) 1.5% 1.5% 1.5% 1.5%
Coated Fine Aggregate (containing micro silica in an amount equal to about 2% by weight of fine aggregate i.e. 15kg of micro silica) - - 755 755
Compressive Strength (in MPa)
1 day 49.8 54.7 58.8 64.0
3 days 71.1 78.8 85.2 92.2
7 days 89.9 93.5 101.1 119.3
28 days 118.1 122.4 137.0 147.2
Slump at ‘0’ minutes (mm) >200 mm >200 mm >200 mm >200 mm
Slump after 1 hour (mm) 120 mm 120 mm 150 mm 170mm
Flexural Strength at 28 days (Mpa) 11.1 11.5 12.3 13.8
Splitting Tensile Strength at 28 days (Mpa) 5.1 5.8 7.7 9.0
Abrasion loss (%) 8.8 8.2 7.9 7.0
Water Permeability (mm) 6 mm 3 mm 0 mm 0 mm
RCPT value (Coulombs) after 6 hours <100 <100 20-40 <10 = ‘0’
Compressive Strength at 7 days (Self Cured) 88.8 94.0 103.3 120.1
Compressive strength at 28 days (Self Cured) 117.2 120.8 140.4 146.9
Bond strength between concrete and Fe 500 steel (Mpa) at 28 days 9.2 10.8 13.2 14.6
Bond strength between concrete and Prestressing steel (Fe 1650) at 28 days 12.0 13.6 20.6 22.2
Shear strength of concrete at 28 days (Mpa) 6.0 6.8 7.2 8.8

Example 7:
[0134] A wet concrete mix was manufactured using a pan mixer with a rotating drum and fixed blade. Binder (which is a mix of OPC 53 grade cement and fly ash in a ratio of 70:30, having a first size fraction having MAPS of 70 to 80 microns and a second size fraction having MAPS of 20 to 30 microns), at least one additive and water in an amount to maintain a water-binder ratio of 0.22 were mixed to obtain a slurry. Thereafter, coarse aggregates and fine aggregates and solid fibers having a length in the range of 5 mm to 50 mm as per Table 10 are added and the whole mixture is mixed for 5-6 minutes until a homogenous mix is obtained. The resulting mixes were filled in appropriate molds (relevant for different experiments as per Indian Standards) having the suitable sizes (as per the test to be performed, details of which have been provided above). The completely filled molds were subjected to vibration on the vibrating table until all entrapped air was expelled. Samples were cured in water for 28 days after demolding and stored in a curing tank maintaining temperature conditions as per Indian Standard IS 456-2000.

 
Table 10: Compositional Details of the Concrete and the Results

Ingredients Mix 25 Mix 26 Mix 27 Mix 28
(Weights in KGS or in wt%)
Binder – OPC 53 grade + Fly ash 500 500 500 500
Uncoated coarse Aggregate 1206 - 1206 -
Coated Coarse Aggregate (containing micro silica in an amount equal to 1% by weight of coarse aggregate i.e. 12 kg) - 1218 - 1218
Uncoated Fine Aggregate 740 740 - -
Micro silica added separately 27 15 12 0
Weight % of Poly Carbonate Based Additive added based on weight of Binder + micro silica (if added separately) 1.5% 1.5% 1.5% 1.5%
Coated Fine Aggregate (containing micro silica in an amount equal to about 2% by weight of fine aggregate i.e. 15kg of micro silica) - - 755 755
Solid Fiber dosage 5 5 5 5
Compressive Strength (in MPa)
1 day 50.1 53.2 59.0 65.2
3 days 71.8 78.2 86.2 91.8
7 days 88.6 94.2 103.4 121.0
28 days 116.0 121.1 135.90 147.3
Slump at ‘0’ minutes (mm) >200 mm >200 mm >200 mm >200 mm
Slump after 1 hour (mm) 100 mm 110 mm 130 mm 150mm
Flexural Strength at 28 days (Mpa) 11.2 11.6 12.8 14.0
Splitting Tensile Strength at 28 days (Mpa) 6.2 7.0 8.5 9.9
Abrasion loss (%) 8.0 7.5 7.0 6.8
Water Permeability (mm) 5 mm 3 mm 0 mm 0 mm
RCPT value (Coulombs) after 6 hours <100 <100 20-40 0 to 10
Compressive Strength at 7 days (Self Cured) 88.5 93.6 103.6 121.1
Compressive strength at 28 days (Self Cured) 116.2 121.0 136.6 146.9
Bond strength between concrete and Fe 500 steel (Mpa) at 28 days 9.4 10.7 13.8 15.0
Bond strength between concrete and Prestressing steel (Fe 1650) at 28 days 12.0 13.8 20.5 23.2
Shear strength of concrete at 28 days (Mpa) 5.8 6.6 7.3 9.9
Average Residual Strength (Mpa) 2.8 3.3 3.6 4.4

Example 8:
[0135] A wet concrete mix was manufactured using a pan mixer with a rotating drum and fixed blade. Binder (which is a mix of OPC 53 grade cement and fly ash in a ratio of 70:30, having a first size fraction having MAPS of 70 to 80 microns and a second size fraction having MAPS of 20 to 30 microns), at least one additive and water in an amount to maintain a water-binder ratio of 0.22 were mixed to obtain a slurry. Thereafter, coarse aggregates and fine aggregates and hollow fibers having a length in the range of 5 mm to 50 mm as per Table 11 are added and the whole mixture is mixed for 5-6 minutes until a homogenous mix is obtained. The resulting mixes were filled in appropriate molds (relevant for different experiments as per Indian Standards) having the suitable sizes (as per the test to be performed, details of which have been provided above). The completely filled molds were subjected to vibration on the vibrating table until all entrapped air was expelled. Samples were cured in water for 28 days after demolding and stored in a curing tank maintaining temperature conditions as per Indian Standard IS 456-2000.

Table 11: Compositional Details of the Concrete and the Results
Ingredients Mix 29 Mix 30 Mix 31 Mix 32
(Weights in KGS)
Binder – OPC 53 grade + Fly ash 500 500 500 500
Uncoated coarse Aggregate 1206 - 1206 -
Coated Coarse Aggregate (containing micro silica in an amount equal to 1% by weight of coarse aggregate i.e. 12 kg) - 1218 - 1218
Uncoated Fine Aggregate 740 740 - -
Micro silica added separately 27 15 12 0
Weight % of Poly Carbonate Based Additive added based on weight of Binder + micro silica (if added separately) 1.5% 1.5% 1.5% 1.5%
Coated Fine Aggregate (containing micro silica in an amount equal to about 2% by weight of fine aggregate i.e. 15kg of micro silica) - - 755 755
Hollow Fiber Dosage (kg) 5 5 5 5
Compressive Strength (in MPa)
1 day 49.8 53.4 58.8 65.4
3 days 70.2 76.0 86.3 92.0
7 days 88.2 93.7 102.9 121.0
28 days 117.1 123.1 137.0 149.0
Slump at ‘0’ minutes (mm) >200 mm >200 mm >200 mm >200 mm
Slump after 1 hour (mm) 110 mm 110 mm 130 mm 150mm
Flexural Strength at 28 days (Mpa) 11.1 11.5 13.5 14.9
Splitting Tensile Strength at 28 days (Mpa) 6.3 7.0 8.8 10.2
Abrasion loss (%) 8.0 7.5 6.8 6.5
Water Permeability (mm) 5 mm 2 mm 0 mm 0 mm
RCPT value (Coulombs) after 6 hours <100 <100 20-40 0 - 10
Compressive Strength at 7 days (Self Cured) 87.3 93.2 102.9 121.2
Compressive strength at 28 days (Self Cured) 115.8 120.2 135.8.6 147.2
Bond strength between concrete and Fe 500 steel (Mpa) at 28 days 9.5 11.2 14.0 15.6
Bond strength between concrete and Prestressing steel (Fe 1650) at 28 days 12.2 13.9 20.8 23.8
Shear strength of concrete at 28 days (Mpa) 5.6 6.5 7.4 9.7
Average Residual strength deflection (Mpa) 3.0 3.7 3.9 5.6

Observations:
[0136] It can be seen from Table 4, Mix 3 and Mix 4 are both better than Mix 1, which is the benchmark. Mix 4 which has both coated coarse aggregate and coated fine aggregate is better than Mix 2 (which solely has coated coarse aggregate) and Mix 3 (which solely has coated fine aggregate).

[0137] It can be seen from Table 5, Mix 7 and Mix 8 are both better than Mix 5, which is the benchmark. Mix 8 which has both coated coarse aggregate and coated fine aggregate is better than Mix 6 (which solely has coated coarse aggregate) and Mix 7 (which solely has coated fine aggregate).

[0138] It can be seen from Table 6, Mix 11 and Mix 12 are both better than Mix 9, which is the benchmark. Mix 12 which has both coated coarse aggregate and coated fine aggregate is better than Mix 10 (which solely has coated coarse aggregate) and Mix 11 (which solely has coated fine aggregate).

[0139] It can be seen from Table 7, Mix 15 and Mix 16 are both better than Mix 13, which is the benchmark. Mix 16 which has both coated coarse aggregate and coated fine aggregate is better than Mix 14 (which solely has coated coarse aggregate) and Mix 15 (which solely has coated fine aggregate).

[0140] It can be seen from Table 8, Mix 19 and Mix 20 are both better than Mix 17, which is the benchmark. Mix 20 which has both coated coarse aggregate and coated fine aggregate is better than Mix 18 (which solely has coated coarse aggregate) and Mix 19 (which solely has coated fine aggregate).

[0141] It can be seen from Table 9, Mix 23 and Mix 24 are both better than Mix 21, which is the benchmark. Mix 24 which has both coated coarse aggregate and coated fine aggregate is better than Mix 22 (which solely has coated coarse aggregate) and Mix 23 (which solely has coated fine aggregate).

[0142] It can be seen from Table 10, Mix 27 and Mix 28 are both better than Mix 25, which is the benchmark. Mix 28 which has both coated coarse aggregate and coated fine aggregate is better than Mix 26 (which solely has coated coarse aggregate) and Mix 27 (which solely has coated fine aggregate).

[0143] It can be seen from Table 11, Mix 31 and Mix 32 are both better than Mix 29, which is the benchmark. Mix 32 which has both coated coarse aggregate and coated fine aggregate is better than Mix 30 (which solely has coated coarse aggregate) and Mix 31 (which solely has coated fine aggregate).

[0144] On comparing the data contained in Table 4 to Table 11, it can be observed that Mix 32 is better than Mix 28, which is better than Mix 24, which is better than Mix 20, which is better than Mix 16, which is better than Mix 12, which is better than Mix 8, and which is better than Mix 4 (in terms of at least one property of the concrete structure).

[0145] Owing to plurality of reasons, concrete structure having compressive strength to the extent of 150 MPa to 200 MPa can be prepared by following the teachings of the present invention. Also, other benefits which are stated in each of Table 4 to Table 11 can be attained.

[0146] Apart from the above, the dampening effect of concrete added with hollow fibers in place of solid fibers improved, showing earthquake resistant properties of hollow fiber reinforced concrete compared to solid fiber reinforced concrete, apart from enhancing the average residual strengths of hollow fiber reinforced concretes, as shown in the table above.

[0147] On the other hand, there is also an upper limit as to the amount of micro silica that can be provided on the fine aggregate. Roughly speaking, maximum benefit is derived when the fine aggregate has a layer of micro silica thereupon, wherein the amount of micro silica is less than approximately 5% by weight of the fine aggregate. Roughly speaking, maximum benefit is derived when the coarse aggregate has a layer of micro silica thereupon, wherein the amount of micro silica is less than approximately 5% by weight of the coarse aggregate.

[0148] In case, the amount of micro silica forming part of the layer provided on the fine aggregate is greater than about 5% by weight of the fine aggregate, the benefits are not substantial. In case, the amount of micro silica forming part of the layer provided on the coarse aggregate is greater than about 5% by weight of the coarse aggregate, the benefits are not substantial.

[0149] Although various options for coating of the fine aggregate (with materials other than micro-silica) are available in the current market, the same do not result in such enhancement of the properties of the concrete structure. The unique properties of micro silica, when applied as a coating on the fine aggregate, improve the microstructure of the concrete, offering superior performance in terms of reduced porosity, increased compressive strength, and better resistance to environmental factors. This thick micro silica coating thus provides a clear advantage over conventional coatings on the fine aggregate in terms of enhancing the concrete's mechanical properties and durability.

[0150] The application of a micro silica coating on fine aggregates, which are inherently siliceous, offers a non-obvious yet highly beneficial enhancement to concrete mixtures. While fine aggregates, such as sand or crushed fine stones, already contain silica, the idea of further coating them with micro silica might initially seem redundant. However, experimental results demonstrated that the micro silica coating on fine aggregates (even if the same is inherently siliceous) significantly improves the concrete's properties. The coating enhances the bond between the fine aggregates and the binder, strengthening the interfacial transition zone and improving the overall compressive strength. Additionally, it reduces the water absorption and porosity of the mixture, leading to greater durability and resistance to environmental factors. The micro silica also helps fill micro voids and microcracks, contributing to the concrete’s long-term durability and wear resistance. This non-obvious approach, confirmed through experimentation, results in a concrete mixture with superior strength, reduced permeability, and enhanced performance, especially in harsh environmental conditions, offering a novel advancement in concrete mixture.

[0151] While specific language has been used to describe the disclosure, any limitations arising on account of the same are not intended. As would be apparent to a person in the art, various working modifications may be made to the method in order to implement the inventive concept as taught herein. The figures and the foregoing description give examples of embodiments. Those skilled in the art will appreciate that one or more of the described elements may well be combined into a single functional element. Alternatively, certain elements may be split into multiple functional elements. Elements from one embodiment may be added to another embodiment. For example, orders of processes described herein may be changed and are not limited to the manner described herein. The scope of embodiments is by no means limited by these specific examples. Numerous variations, whether explicitly given in the specification or not, such as differences in structure, dimension, and use of material, are possible. The scope of embodiments is at least as broad as given by the following claims.
 
, Claims:1. A composition for making concrete structure having enhanced properties, said composition comprises:
coarse aggregates in an amount of 20 to 50 wt.% of the composition;
fine aggregates in an amount of 15 to 45 wt.% of the composition;
optionally binder material in an amount of 10 to 25 wt.% of the composition; and
optionally at least one additive in an amount of 0 to 5 wt.% of the composition;
the coarse aggregate optionally comprising a layer of micro silica thereupon; and
the fine aggregate comprising a layer of micro silica thereupon, an amount of micro silica being in the range of 0.1 to 5.0 wt.% of the fine aggregate.

2. The composition as claimed in claim 1, wherein the composition is in at least two-part form comprising:
(a) a first part comprising:
(i) coarse aggregates in an amount of 20 to 50 wt.% of the composition,
(ii) the fine aggregates in an amount of 15 to 45 wt.% of the composition, and
(iii) optionally at least one additive,
the coarse aggregate optionally comprising a layer of micro silica thereupon; and
the fine aggregate comprising a layer of micro silica thereupon, an amount of micro silica being in the range of 0.1 to 5.0 wt.% of the fine aggregate; and
(b) a second part comprising:
(i) the binder material in an amount of 10 to 25 wt.% of the composition; and
(ii) optionally at least one additive;
the at least one additive is present in an amount of 0 to 5 wt.% of the composition.

3. The composition as claimed in claim 1, wherein the binder material comprises a first material selected from a group comprising of Portland cement, modified Portland cement, or masonry cement, hydraulic hydrated lime, white cement, calcium aluminate cement, silicate cement, phosphate cement, high-alumina cement, magnesium oxychloride cement, oil well cements, and combinations thereof; optionally a second material selected from a group comprising of blast furnace slag, chemically modified blast furnace slag, Lightweight Expanded Clay Aggregate (LECA), Calcined Clay (Metastar), Red Brick Dust (RBD), Tile and Yellow Brick Dust (YBD) and combinations thereof; optionally a third material selected from a group comprising of fly ash, chemically modified fly ash, Pulverised Fuel Ash (PFA), Rice Husk Ash (RHA), volcanic ash material, finely ground quartz material, chemically modified quartz, pond ash, and combination thereof; and optionally a fourth material selected from a group comprising sodium sulphate, micro silica, lime, and combination thereof.

4. The composition as claimed in claim 1, wherein the at least one additive is selected from a group comprising of Melamine, Lignosulphonate, Sulphonated Naphthalene Formaldehyde, Sulphonated melamine formaldehyde, Polycarboxylate based compound, carbon nanotube (CNT) based additives, sodium hydroxide, potassium hydroxide, magnesium hydroxide and combinations thereof.

5. The composition as claimed in claim 1, wherein the micro silica has a size in the range of 1 nano meter to 10 microns.

6. The composition as claimed in claim 1, wherein the fine aggregate further comprises activated calcium hydroxide.

7. The composition as claimed in claim 1, wherein the composition is dry and is adapted to be mixed with water in an amount of 4 to 8 wt.% of the composition for making a wet concrete mass suitable for making concrete structures.

8. The composition as claimed in claim 1, wherein at least one of:
the coarse aggregate comprises the layer of micro silica thereupon;
an amount of micro silica being in the range of 0.1 to 2.0 wt.% of the coarse aggregate; and
the composition optionally comprises fibers in an amount of 1 to 5 wt% of the composition, the fibers having a length in the range of 5 mm to 50 mm.

9. The composition as claimed in claim 8, wherein at least one of:
the fibers are solid and have an external diameter in the range of 1 to 5 mm; and
the fibers are hollow and have an external diameter in the range of 1.1 to 6 mm and an internal diameter in the range of 1 to 5 mm.

10. The composition as claimed in claim 1, wherein the binder material comprises two or more fractions that are different from each other in term of their mode average particle size (MAPS).

11. The composition as claimed in claim 1, wherein the binder material comprises:
a first binder size fraction having MAPS in the range of 70 to 80 microns; an amount of the first binder size fraction being in a range of 50 to 85 wt.% of the amount of the binder material;
a second binder size fraction having MAPS in the range of 20 to 30 microns; an amount of the second binder size fraction being in a range of 20 to 40 wt.% of the amount of the first binder size fraction;
optionally, a third binder size fraction having MAPS in the range of 3 to 8 microns; an amount of the third binder size fraction being in a range of 20 to 40 wt.% of the amount of the second binder size fraction; and
optionally, a fourth binder size fraction having MAPS in the range of 0.01 to 2 microns; the fourth binder size fraction constituting a remaining amount of the binder material.

12. The composition as claimed in claim 3, wherein at least one of:
a. the first material forming part of the binder material comprises:
i. a first material first size fraction having MAPS in the range of 70 to 80 microns; an amount of the first material first size fraction being in a range of 50 to 85 wt.% of the amount of the first material;
ii. a first material second size fraction having MAPS in the range of 20 to 30 microns; an amount of the first material second size fraction being in a range of 20 to 40 wt.% of the amount of the first material first size fraction; and
iii. optionally a first material third size fraction having MAPS in the range of 3 to 8 microns; the first material third size fraction constituting a remaining amount of the binder material; and
b. the second material forming part of the binder material comprises:
i. a second material first size fraction having MAPS in the range of 70 to 80 microns; an amount of the second material first size fraction being in a range of 50 to 85 wt.% of the amount of the second material;
ii. a second material second size fraction having MAPS in the range of 20 to 30 microns; an amount of the second material second size fraction being in a range of 20 to 40 wt.% of the amount of the second material first size fraction;
iii. optionally, a second material third size fraction having MAPS in the range of 3 to 8 microns; the second material third size fraction constituting a remaining amount of the binder material; an amount of the second material third size fraction being in a range of 20 to 40 wt.% of the amount of the second material second size fraction; and
iv. optionally, a second material fourth size fraction having MAPS in the range of 0.01 to 2 microns; the second material fourth size fraction constituting a remaining amount of the second material.

13. A method for preparing wet concrete mass suitable for making concrete structures, said process comprising: mixing a composition comprising coarse aggregates in an amount of 20 to 50 wt.% of the composition, fine aggregates in an amount of 15 to 45 wt.% of the composition, and optionally binder material in an amount of 10 to 25 wt.% of the composition; and optionally at least one additive in an amount of 0 to 5 wt.% of the composition, the coarse aggregate optionally comprising a layer of micro silica thereupon; and the fine aggregate comprising a layer of micro silica thereupon, an amount of micro silica being in the range of 0.1 to 5.0 wt.% of the fine aggregate with water in an amount of 4 to 8 wt.% of the composition to obtain the wet concrete mass.

14. The method as claimed in claim 13, wherein the composition is in at least two-part form comprising:
(a) a first part comprising the coarse aggregates, the fine aggregates, and optionally at least one additive, the coarse aggregate optionally comprising a layer of micro silica thereupon; and the fine aggregate comprising a layer of micro silica thereupon, an amount of micro silica being in the range of 0.1 to 5.0 wt.% of the fine aggregate; and
(b) a second part comprising the binder material; and optionally at least one additive; and
the step of mixing comprises mixing the second part comprising the binder material and optionally the at least one additive with water to obtain a first slurry; mixing the first part comprising the coarse aggregates, optionally comprising a layer of micro silica thereupon, the fine aggregates comprising the layer of micro silica thereupon and optionally the at least one additive with the first slurry in any sequence to obtain the wet concrete mass.

15. A method for preparing the composition as claimed in claim 1, said process comprising:
obtaining coarse aggregates optionally comprising a layer of micro silica thereupon;
obtaining fine aggregates comprising a layer of micro silica thereupon, an amount of micro silica being in the range of 0.1 to 5.0 wt.% of the fine aggregate;
mixing the coarse aggregate thus obtained with the fine aggregate thus obtained such that the coarse aggregates optionally comprising the layer of micro silica is in an amount of 20 to 50 wt.% of the composition, and the fine aggregates comprising the layer of micro silica thereupon is present in an amount of 15 to 45 wt.% of the composition;
providing a binder material in an amount of 10 to 25 wt.% of the composition; and
optionally providing at least one additive the at least one additive being present in an amount of 0 to 5 wt.% of the composition.

16. The method as claimed in claim 15, wherein the coarse aggregate comprises the layer of micro silica thereupon, and the same is obtained by:
contacting wet coarse aggregate with solid micro silica to obtain wet coated coarse aggregate; and
drying the wet coated coarse aggregate to obtain the coarse aggregate having a layer of micro silica thereupon;
the amount of micro silica, and the amount of water being such that the coarse aggregate comprises 0.1 to 2.0 wt.% of micro silica layer thereupon, the weight percentage being based on a weight of the coarse aggregate.

17. The method as claimed in claim 15, wherein the fine aggregate comprising the layer of micro silica thereupon is obtained by:
contacting wet fine aggregate with solid micro silica to obtain wet coated fine aggregate; and
drying the wet coated fine aggregate to obtain the fine aggregate having a layer of micro silica thereupon;
the amount of micro silica, and the amount of water being such that the fine aggregate comprises 0.1 to 5.0 wt.% of micro silica layer thereupon, the weight percentage being based on a weight of the fine aggregate.

18. In an embodiment of the invention, the fine aggregate further comprises activated calcium hydroxide and the same is obtained by:
obtaining a wet fine aggregate comprising fine aggregate, calcium carbide, water and micro silica;
igniting the wet fine aggregate so as to dry the wet fine aggregate to obtain a mixture comprising activated calcium hydroxide and fine aggregate having a layer of micro silica thereupon;
the amount of micro silica, and the amount of water being such that the fine aggregate comprises 0.1 to 5.0 wt.% of micro silica layer thereupon, the weight percentage being based on a weight of the fine aggregate.

Dated this 21st day of January 2025