Description:FIELD OF INVENTION
[001] The present invention relates to a composition for preparing a Portland cement free binder from industrial waste and a method thereof. Particularly, the present invention relates to a composition and method for preparing a binder free from Portland cement using industrial waste with reduced energy consumption and minimal environmental impact.

BACKGROUND OF THE INVENTION
[002] In today’s world, sustainable development is an important aspect as it aims towards conservation of natural resources by promoting sustained use of the natural resources. Such sustainability must be maintained in all economic sectors of the country. The construction industry faces challenges to stay on the path of sustainability. The sustainability in construction industry may be maintained by reducing gross energy consumption, emissions leading to pollution and minimizing the consumption of non-renewable natural resources.

[003] Concrete is one of the most widely utilized building material due to its durability, low cost, easy utilization and transportation. However, the production of hydraulic binder used for concrete exhibits adverse impact on environment. Portland cement based binders are widely used binders in concrete. However, preparation of such binders emits greenhouse gases such as carbon dioxide. Moreover, such binders are prone to sulphate attack due to reactions taking place with hydration products leading to the production of gypsum and ultimately ettringite, which is expansive and may result in concrete disintegration. Therefore, there is a need of Portland cement free binder that does not pose any risk to the environment and contribute towards formation of sustainable concrete.

[004] There are several patent applications that disclose a composition for preparing Portland cement binders. A Chinese Patent Application CN109790072B discloses a cold-melt concrete formulation that comprises of a mixture of water, silica-based mineral aggregate as filler; sodium or potassium metasilicate/pentahydrate as an activator; waste from steel production processes, including granulated blast furnace slag powder, as a cement-based constituent; high or low calcium waste (fly ash or bottom ash) from coal combustion as a cement-based constituent; sodium tetraborate, sodium citrate dihydrate, citric acid or boric acid as a set retarder; a fortifier comprising a hydroxide of calcium, potassium, magnesium, sodium or aluminum; attapulgite, kaolin, red clay or other fine particle size, high aluminosilicate containing clays for increasing the silica and aluminosilicate concentration and associated strength; protein or synthetic protein material to form weak covalent bonds with hydroxides and silicates for maintaining consistent volume during solidification; and pollinated fern oil to reduce the water content and viscosity of the mixture. However, the prior art uses sodium metasilicate in the activator composition. Sodium metasilicate manufacturing involves fusion of silica and sodium bearing compounds at high temperatures of around 1500º C and hence involves a very high energy intensive process.

[005] Another Canadian Patent Application CA3109560A1 discloses Class C fly ash (CFA) cementitious composition for construction, building and oil industries comprising with a controllable setting time comprising at least one Class C fly ash; at least one alkali hydroxide; at least one source of phosphate; and water. However, the prior art fails to disclose the pH modification of polyphosphate and sulfates. Moreover, the prior art fails to disclose the use of amines in activator composition.

[006] Therefore, keeping in view the problems associated with the state of the art there is a need of an efficient, safe, stable alkali activated Portland cement free binder composition suitable for preparing sustainable concrete.

OBJECTIVE OF THE INVENTION
[007] The primary objective of the present invention is to provide a composition for preparing a Portland cement free binder from industrial waste and a method thereof.

[008] Another objective of the present invention is to provide a natural, safe, stable binder free from Portland cement by using industrial waste with reduced energy consumption and minimal environmental impact.

[009] Yet another objective of the present invention is to provide a method for preparing a binder without employing clinkering process, thereby resulting in reduced emission of greenhouse gases and hence posing minimal impact on the environment.

[0010] Yet another objective of the present invention is to provide an alkali activated Portland cement free binder composition suitable for preparing sustainable concretes.

[0011] Other objectives and advantages of the present invention will become apparent from the following description taken in connection with the accompanying drawings, wherein, by way of illustration and example, the aspects of the present invention are disclosed.

SUMMARY OF THE INVENTION
[0012] The present invention relates to a composition for preparing a Portland cement free binder from industrial waste and a method thereof. The composition for preparing Portland cement free binder from industrial waste comprises of a plurality of pozzolanic material and a plurality of activators. The pozzolanic material used in the present invention includes industrial byproducts selected from a group consisting of such as, but not limited to, fly ash and ground granulated blast furnace slag, or a combination thereof. The pozzolanic material may be present in a range of 70% to 98% by weight of the total composition wherein the fly ash may be present in the amount up to 20% by weight of pozzolanic material and the remaining amount of pozzolanic material may be ground granulated blast furnace slag . The activators may be present in a range of 2% to 30% by weight of the total composition selected from the alkali metal oxide and hydroxide, the alkali metal carbonate, the alkali metal sulfate, the alkali metal phosphate, the tertiary amines, and the alkali salt of polyacrylic acid, or a combination thereof. The present invention relates to a composition and method for preparing a binder free from Portland cement by using industrial waste with reduced energy consumption and minimal environmental impact.

BRIEF DESCRIPTION OF DRAWINGS

[0013] The present invention will be better understood after reading the following detailed description of the presently preferred aspects thereof with reference to the appended drawings, in which the features, other aspects and advantages of certain exemplary embodiments of the invention will be more apparent from the accompanying drawing in which:

[0014] Figure 1 is a flowchart depicting a method (100) for preparing a Portland cement free binder from industrial waste.

DETAILED DESCRIPTION OF EMBODIMENTS
[0015] The following detailed description and embodiments set forth herein below are merely exemplary out of the wide variety and arrangement of instructions, which can be employed with the present invention. The present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. All the features disclosed in this specification may be replaced by similar other or alternative features performing similar or same or equivalent purposes. Thus, unless expressly stated otherwise, they all are within the scope of the present invention.

[0016] Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the embodiments described herein can be made without departing from the scope of the invention. In addition, descriptions of well-known functions and constructions are omitted for clarity and conciseness.

[0017] The terms and words used in the following description and claims are not limited to the bibliographical meanings but are merely used to enable a clear and consistent understanding of the invention. Accordingly, it should be apparent to those skilled in the art that the following description of exemplary embodiments of the present invention are provided for illustration purpose only and not for the purpose of limiting the invention.

[0018] It is to be understood that the singular forms “a”, “an” and “the” include plural referents unless the context clearly dictates otherwise.

[0019] It should be emphasized that the term “comprises/comprising” when used in this specification is taken to specify the presence of stated features, integers, steps, or components but does not preclude the presence or addition of one or more other features, integers, steps, components, or groups thereof.

[0020] Accordingly, the present invention relates to a composition for preparing a Portland cement free binder from industrial waste and a method thereof. Particularly, the present invention relates to a composition and method for preparing a binder free from Portland cement using industrial waste with reduced energy consumption and minimal environmental impact.

[0021] In an embodiment, the composition for preparing a binder from industrial waste comprises a plurality of pozzolanic material and at least one activator.

[0022] The pozzolanic materials are siliceous and aluminous material that forms compounds with cementitious properties reacting with calcium hydroxide in the presence of moisture. In an exemplary embodiment, the pozzolanic material used in the present invention may include industrial byproducts selected from a group consisting of such as, but not limited to, fly ash and ground granulated blast furnace slag, or a combination thereof. In another exemplary embodiment, the fly ash may be selected from a group consisting of such as, but not limited to, Class C fly ash and Class F fly ash, or a combination thereof. In an exemplary embodiment, the pozzolanic material may be present in a range of 70% to 98% by weight of the total composition. In another exemplary embodiment, each pozzolanic material may be present in different amounts such as fly ash may be present in an amount up to 20% by total weight of pozzolanic material and the remaining amount of the pozzolanic material may be ground granulated blast furnace slag. In yet another exemplary embodiment, the pozzolanic material in the present invention may be used in different forms such as, but not limited to, powdered form.

[0023] The activator used in the present invention activates the hydraulically active and pozzolanic materials/minerals present in the industrial wastes by increasing the pH. With the increase in pH the minerals present in the industrial waste dissolve and re-arrange to form solid thereby imparting enhanced compressive strength and decrease the swelling capacity of the soil to which the binder is added. In an exemplary embodiment, the activators used in the present invention may be selected from a group consisting of such as, but not limited to, alkali metal oxide and hydroxide, alkali metal carbonate, alkali metal sulfate, alkali metal phosphate, tertiary amine, and alkali salt of polyacrylic acid, or a combination thereof. In another exemplary embodiment, the alkali metal oxide and hydroxide may be selected form a group consisting of such as, but not limited to, sodium hydroxide, calcium hydroxide, magnesium hydroxide, lithium hydroxide, or a combination thereof. In a preferred embodiment, the alkali metal hydroxide may be selected from a group consisting of, such as, but not limited to, sodium hydroxide, calcium hydroxide, or a combination thereof. In another exemplary embodiment, the alkali metal carbonate may be selected from a group consisting of such as, but not limited to, calcium carbonate, magnesium carbonate, barium carbonate, sodium carbonate, or a combination thereof. In a preferred embodiment, calcium carbonate may be used an alkali metal carbonate. In another exemplary embodiment, the alkali metal sulfate may be selected from a group consisting of such as, but not limited to, sodium sulfate, calcium sulfate, magnesium sulfate, or a combination thereof. In a preferred embodiment, sodium sulfate may be used as an alkali metal sulfate. In another exemplary embodiment, the alkali metal phosphate may be selected from a group consisting of such as, but not limited to, sodium hexametaphosphate, Potasium hexametaphosphate, or a combination thereof. In a preferred embodiment, sodium hexametaphosphate may be used as alkali metal phosphate. In yet another exemplary embodiment, the tertiary amine may be selected from a group consisting of such as, but not limited to, 2-[bis(2-hydroxyethyl)amino]ethanol, N,N-bis(2-hydroxyethyl)isopropanolamine or 1,1',1''-Nitrilotri(propan-2-ol), or a combination thereof. In another exemplary embodiment, the activators may be present in a range of 2% to 30% by weight of the total composition. In another exemplary embodiment, the alkali salt of polyacrylic acid may be selected from a group consisting of such as, but not limited to sodium polyacrylate, potassium polyacrylate, or a combination thereof. In yet another exemplary embodiment, different activators may be used in different forms such as, but not limited to, solid form and liquid form, for instance, alkali metal oxide and hydroxide, alkali metal carbonate, alkali metal sulfate, alkali metal phosphate, and alkali salt of polyacrylic acid may be used in solid form; and tertiary amine may be used in liquid form.

[0024] In an exemplary embodiment, the particle size of the activator impacts the strength of the binder composition such that if the particle size increases, the strength of the binder composition decreases. In a preferred embodiment, the alkali metal carbonate, such as calcium carbonate used in the present invention has a particle size in a range of 6-12 microns.

[0025] In another exemplary embodiment, the pH value of the alkali metal sulfate and alkali metal phosphate used in the present invention is greater than 9, which helps to dissolve the pozzolanic material with the activator.

[0026] In another embodiment, the present invention also relates to a method (100) for preparing a Portland cement free binder from industrial waste. The method comprises the following steps:

a) mixing pozzolanic materials thoroughly in an apparatus ( Step 105);
b) adding activators to the mixture obtained in step 105 (Step 110);
c) mixing the pozzolanic materials and activators in the apparatus until a homogenous mixture is obtained (Step 115);
d) spraying liquid activator from a liquid spray system equipped in a blender to the homogenous mixture obtained in step 115 for uniform blending of pozzolanic material, activators, and liquid component (Step 120); and
e) blending the mixture obtained in step 120 to form a binder (Step 125).

[0027] In an exemplary embodiment, the apparatus used in the present invention may include, such as, but not limited to, a high precision blender.

[0028] In an exemplary embodiment, the liquid is selected from, such as, but not limited to, tertiary amines.

[0029] The following illustrates the experimental data of the present invention and should not be construed to limit the scope of the present invention.

Experimental Data

[0030] An experimental study was performed to determine physical properties such as consistency and molar compressive strength of the binder composition prepared in the present invention as per IS 4031. Four different batches of 50 kg each having different composition were prepared. The batches prepared were as follow:

Table 1
Components C1 (in %) C2 (in %) C3 (in %) C4 (in %)
Ground granulated blast furnace slag 70 65 65 87
Class F Fly Ash 20 20 20 0
Micro Calcium Carbonate 0 5 5 0
Sodium Hydroxide 2 2 2 0
Calcium Hydroxide 0 0 0 5
Sodium Sulfate 8 8 8 3
Sodium Hexametaphosphate 0 0 0 5
2-[bis(2-hydroxyethyl)amino]ethanol (TEA) 0.025 0.025 0.025 0
N,N-bis(2-hydroxyethyl)isopropanolamine (DEIPA) 0.025 0.025 0 0
1,1',1''-Nitrilotri(propan-2-ol) (TIPA)
0 0 0.025 0
Physical Properties
Consistency (in %) 27 28 28.5 28
Initial Setting Time (Mts) 150 120 180 165
Final Setting Time (Mts) 210 180 210 245
Mortar Compressive Strength (Mpa) (in %)
1 Day 8.2 7.4 7.2 22
3 Days 20.6 19.6 18.2 34.8
7 Days 31.8 30.5 31.5 38.8
28 Days 42.5 45.9 43.8 44.5

[0031] It was reported that when the concentration of all the components was kept constant in batch C2 and C3 except for N,N-bis(2-hydroxyethyl)isopropanolamine (DEIPA) and 1,1',1''-Nitrilotri(propan-2-ol) (TIPA) such that N,N-bis(2-hydroxyethyl)isopropanolamine was present only in C2 in a concentration 0.025% and 1,1',1''-Nitrilotri(propan-2-ol) (TIPA) was only present in C3 in concentration 0.025%, a minor variation was reported in consistency and molar compressing strength of batch C2 and batch C3. The consistency of batch C2 was reported to be 28% between initial setting time of 120 minutes and final setting time of 180 minutes and the consistency of batch C3 was reported to be 28.5% between initial setting time of 180 minutes and final setting time of 210 minutes. Further, it was reported that the compressive strength of batch C2 increased from 7.4% (day 1) to 19.6% (day 3) to 30.5% (day 7) and 45.9 (day 28). Similarly, it was reported that the compressive strength of the batch C3 was increased from 7.2 (day 1) to 18.2 (day 3) to 31.5 (day 7) and 43.8 (day 28). Therefore, a conclusion was made that the presence of 1, 1', 1''-Nitrilotri(propan-2-ol) (TIPA) in C3 as compared to the presence of N,N-bis(2-hydroxyethyl)isopropanolamine in C2 contributed towards higher consistency in batch C3. However, presence of N, N-bis(2-hydroxyethyl)isopropanolamine in C2 as compared to the presence of 1,1',1''-Nitrilotri(propan-2-ol) (TIPA) in C3 contributed towards higher compressive strength in batch C2.

[0032] It was also reported that the increased concentration of ground granulated blast furnance slag, calcium hydroxide, sodium hexametaphosphate in batch C4 as compared to batch C1 resulting in higher consistency of batch C4 i.e. 28% between initial setting time of 165 minutes and final setting time of 245 minutes as compared to batch C1 with consistency of 27% between initial setting time of 150 minutes and final setting time of 210 minutes. Furthermore, it was also reported that the increased concentration of ground granulated blast furnance slag, calcium hydroxide, sodium hexametaphosphate in batch C4 as compared to batch C1 also resulted in increase in compressive strength in batch C4 i.e. 22% (day 1) to 34.8% (day 3) to 38.8% (day 7) and 44.5% (day 28) as compared to batch C1 which showed slightly increase in compressive strength i.e. 8.2% (day 1) to 20.6% (day 3) to 31.8% (day 7) and 42.5 (day 28).

[0033] The present invention exhibits following advantages:

• The present invention provides a natural, safe, stable binder free from Portland cement by using industrial waste with reduced energy consumption.
• The present invention provides a method for preparing a binder composition without employing clinkering process, thereby resulting in reduced emission of greenhouse gases and hence posing minimal impact on the environment.

[0034] While this invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the scope of the appended claims.
, Claims:WE CLAIM:
1. A composition for preparing a Portland cement free binder from industrial waste, comprising:
• a plurality of pozzolanic material in a range of 70-98% by weight of total composition; and
• at least one activator in a range of 2-30% by weight of total composition.

2. The composition as claimed in claim 1, wherein the pozzolanic material is selected from a group consisting of fly ash, ground granulated blast furnace slag, or a combination thereof.

3. The composition as claimed in claim 2, wherein the fly ash is present in an amount up to 20% by total weight of pozzolanic material and the remaining amount is ground granulated blast furnace slag.

4. The composition as claimed in claim 1, wherein the activator is selected from the group of alkali metal oxide and hydroxide, the alkali metal carbonate, the alkali metal sulfate, the alkali metal phosphate, the tertiary amines, and the alkali salt of polyacrylic acid, or a combination thereof.

5. The composition as claimed in claim 4, wherein alkali metal oxide and hydroxide is selected from a group consisting of such as but not limited to sodium hydroxide, calcium hydroxide, Magnesium hydroxide, lithium hydroxide, or a combination thereof.
6. The composition as claimed in claim 4, wherein the alkali metal carbonate is selected from a group consisting of calcium carbonate, Magnesium Carbonate, barium carbonate, Sodium carbonate, or a combination thereof.
7. The composition as claimed in claim 4, wherein the alkali metal sulfate is selected from a group consisting of such as, but not limited to, sodium sulfate, Calcium Sulfate, Magnesium Sulfate, or a combination thereof.
8. The composition as claimed in claim 4, wherein the alkali metal phosphate is selected from a group consisting of such as, but not limited to, sodium hexametaphosphate, Potasium hexameta phosphate, or a combination thereof.
9. The composition as claimed in claim 4, wherein the tertiary amine is selected from a group consisting of such as, but not limited to, 2-[bis(2-hydroxyethyl)amino]ethanol, N,N-bis(2-hydroxyethyl)isopropanolamine or 1,1',1''-Nitrilotri(propan-2-ol), or a combination thereof.
10. The composition as claimed in claim 6, wherein the alkali metal carbonate exhibits particle size in a range of 6-12 micron.
11. The composition as claimed in claims 7-8, wherein the alkali metal sulfate and alkali metal phosphate exhibit a pH value greater than 9.
12. A method (100) for preparing a Portland cement free binder from industrial waste comprising the following steps:
a) mixing pozzolanic materials thoroughly in an apparatus (Step 105);
b) adding activators to the mixture obtained in step 105 (Step 110);
c) mixing the pozzolanic materials and activators in the apparatus for until a homogenous mixture is obtained (Step 115);
d) spraying liquid activator from a liquid spray system equipped in a blender to the homogenous mixture obtained in step 115 for uniform blending of pozzolanic material, activators, and liquid component (Step 120); and
e) blending the mixture obtained in step 120 to form a binder (Step 125).