Claims:We Claim:

1. A building material (100), comprising:
a binder and fillers, the binder comprising composition in weight percentage of:
calcium aluminate cement of about 15% to 35%,
steel slag of about 5% to 50%,
calcium sulfate hemihydrate of about 1% to 10%, and
calcium carbonate of about 1% to 40%.

2. The building material (100) as claimed in claim 1, wherein the building material is a wallboard.

3. The building material (100) as claimed in claim 1, wherein the steel slag is an industrial waste.

4. The building material (100) as claimed in claim 3, wherein the steel slag is in at least one of powder form and granular form of a size that passes completely through a 600µm sieve.

5. The building material (100) as claimed in claim 1, wherein the calcium carbonate has a particle size of about 4 micron to 50 micron.

6. The building material (100) as claimed in claim 1 comprises additives, wherein the additives are added to the binder to control rheology and setting time of the binder.

7. The building material (100) as claimed in claim 6, wherein the additives to control rheology includes polycarboxylate ethers, lignosulfonates, polyethylene glycols.

8. The building material (100) as claimed in claim 6, wherein the additives to control setting time of the binder includes borax, citric acid or alkali metal salts of citric acid.

9. The building material (100) as claimed in claim 8, wherein the additives to control setting time of the binder are in the range of about 0.1% to 4%.

10. The building material (100) as claimed in claim 1 comprises fibers, including biofibers, nylon, glass and cellulose.

11. The building material (100) as claimed in claim 10, wherein the fibers are in the range of about 1% to 15%.

12. The building material (100) as claimed in claim 1 comprises accelerators in the range of about 0.01% to 5%.

13. The building material (100) as claimed in claim 12, wherein the accelerators are selected from a group comprising of compounds of lithium such as lithium carbonate, lithium nitrate, lithium hydroxide and/or chromium based compounds such as potassium chromate.

14. The building material as claimed in claim 1 comprises water reducing agents in the range of about 0.1% to 3%.

15. The building material as claimed in claim 14, wherein the water reducing agents includes polycarboxylate ethers, and lingosulfonates.

16. The building material as claimed in claim 1, wherein the fillers are selected from at least one of microspheres, saw dust, perlite and vermiculite.

17. The building material as claimed in claim 1 comprises paper on at least one side of the building material.

18. The building material as claimed in claim 1 comprises foaming agents including hydrogen peroxide and sodium lauryl sulfate.

19. The building material as claimed in claim 18, wherein the foaming agents are in the range of about 0.1% to 3%.

20. A method of manufacturing the building material as claimed in claim 1, the method comprising:
mixing, a binder comprising composition in weight percentage of:
calcium aluminate cement of about 15% to 35%,
steel slag of about 5% to 50%,
calcium sulfate hemihydrate of about 1% to 10%, and
calcium carbonate of about 1% to 40%,
in dry form in a blender to form a dry powder;
adding, pre-determined amount of water to the dry powder in a mixer to form a slurry;
casting, the slurry in a mould;
vibrating, the mould; and
curing the cast in the steel mould for a pre-defined period of time to form the building material.

21. The method as claimed in claim 20, wherein the building material is a wallboard.

22. The method as claimed in claim 20, wherein pre-defined period of time is at least 24 hours.

23. The method as claimed in claim 20, wherein the mixer for mixing the dry powder and water is a shear mixer. , Description:TECHNICAL FIELD

The present disclosure generally relates to the field of structural engineering. Particularly, but not exclusively, the present disclosure relates to a method for manufacturing a building material. Further embodiments of the present disclosure disclose wallboard and a method for manufacturing a wallboard.

BACKGROUND OF THE DISCLOSURE

Wallboard is generally used in construction of residential and commercial buildings to form interior walls, ceilings and also exterior walls in certain situations. As gypsum wallboards are relatively easy to install and requires minimal finishing, they are generally preferred for the purpose of constructing homes and offices.

Gypsum wallboard consists of a hardened gypsum-containing core surfaced with paper or other fibrous material suitable for receiving a coating such as paint. It is common to manufacture gypsum wallboard by placing an aqueous core slurry comprised predominantly of calcined gypsum between two sheets of paper thereby forming a sandwich structure. Various types of cover paper are known in the art. The aqueous gypsum core slurry may be allowed to set or harden by rehydration of the calcined gypsum, usually followed by heat treatment in a dryer to remove excess water. After the gypsum slurry has set (i.e., reacted with water present in the aqueous slurry) and dried, the formed sheet may be cut into required sizes. There are various methods of production of gypsum wallboard known in the art.

Conventionally in the manufacture of gypsum board, the gypsum slurry, which may consist of several additives to reduce weight and add other properties, may be deposited upon a moving paper (or fiberglass matt) substrate. The paper may in turn be supported on a long moving belt. A second paper substrate may then be applied on top of the gypsum slurry to constitute the second face of the gypsum board and the sandwich may be passed through a forming station. The forming station determines the width and thickness of the gypsum board. In such a continuous operation, the gypsum slurry begins to set after passing through the forming station. When sufficient setting has occurred, the board may be cut into commercially acceptable lengths and then passed into a board dryer. Thereafter the board is trimmed and if desired, taped, bundled, shipped, and stored prior to sale.

In the conventional process of manufacture of gypsum wallboard, energy is used throughout the gypsum process. After the gypsum rock is pulled from the ground, it must be dried - typically in a rotary or flash dryer. Then it must be crushed and then calcined. These processes require significant energy just to prepare the gypsum for use in the manufacturing process. After it has been calcined, it may then be mixed typically with hot water (often close to boiling temperature - requiring more energy) to form a hot slurry which begins to set. Further, the boards are cut from the set slurry and are dried in large board driers for about 40 to 60 minutes to evaporate the residual water, which also uses significant energy.

Conventionally known arts, focus on reducing the weight of gypsum board or increasing its strength, or making minor reductions in energy use. For example,US6,699,426 discloses a method which uses additives in gypsum board to reduce the drying time and thus reduce energy usage at the drying stage.

However, in these conventional arts, the use of calcined gypsum is generally assumed(either natural or synthetic), since gypsum wallboard manufacturers would find redesigning the materials and mining procedures from scratch would be expensive and may render their gypsum mines worthless. Given the concerns about climate change, it would not be desirable to manufacture gypsum wallboard which requires significant energy usage during manufacture. Additionally, usage of gypsum wallboards result in emission of greenhouse gases which may cause further harm to the climate.

The present disclosure is intended to overcome one or more limitations stated above or other relevant limitations associated with the conventional arts.

SUMMARY OF THE DISCLOSURE

One or more shortcomings of the conventional techniques are overcome by method and apparatus, as disclosed and additional advantages are provided through the method as described in the present disclosure. Additional features and advantages are realized through the techniques of the present disclosure. Other embodiments and aspects of the disclosure are described in detail herein and are considered a part of the claimed disclosure.

In one non-limiting embodiment of the disclosure, a building material is disclosed. The building material includes a binder and fillers. The binder includes composition in weight percentage of calcium aluminate cement of about 15% to 35%,steel slag of about 5% to 50%,calcium sulfate hemihydrate of about 1% to 10% and calcium carbonate of about 1% to 40%.

In an embodiment of the disclosure, the building material is a wallboard.

In an embodiment of the disclosure, the steel slag is an industrial waste. The steel slag is in at least one of powder form and granular form of a size that passes completely through a 600µm sieve.

In an embodiment of the disclosure, the calcium carbonate has a particle size of about 4 micron to 50 micron.

In an embodiment of the disclosure, the building material comprises additives.The additives are added to the binder to control rheology and setting time of the binder. The additives to control rheology includes polycarboxylate ethers, lignosulfonates, polyethylene glycols. The additives to control setting time of the binder includes borax, citric acid or alkali metal salts of citric acid. The additives to control setting time of the binder are in the range of about 0.1% to 4%.

In an embodiment of the disclosure, the building material comprises fibers, including biofibers, nylon, glass and cellulose. The fibers are in the range of about 1% to 15%.

In an embodiment of the disclosure, the building material comprises accelerators in the range of about 0.01% to 5%. The accelerators are selected from a group comprising of compounds of lithium such as lithium carbonate, lithium nitrate, lithium hydroxide and/or chromium based compounds such as potassium chromate etc.

In an embodiment of the disclosure, the building material comprises water reducing agents in the range of about 0.1% to 3%. The water reducing agents includes polycarboxylate ethers, lingosulfonates.

In an embodiment of the disclosure, the fillers are selected from at least one of microspheres, saw dust, perlite and vermiculite.

In an embodiment of the disclosure, the building material comprises paper on at least one side of the building material.

In an embodiment of the disclosure, the building material comprises foaming agents including hydrogen peroxide and sodium lauryl sulfate. The foaming agents are in the range of about 0.1% to 3%.

In another non-limiting embodiment of the disclosure,a method of manufacturing the building material is disclosed.The method includes mixing a binder comprising composition in weight percentage of calcium aluminate cement of about 15% to 35%,steel slag of about 5% to 50%,calciumsulfate hemihydrate of about 1% to 10% and calcium carbonate of about 1% to 40%in dry form in a blender to form a dry powder. The method includes adding pre-determined amount of water to the dry powder in a mixer to form a slurry. Further the method includes casting the slurry in a mould, vibrating, the mould and curing the cast in the steel mould for a pre-defined period of time to form the building material.

In an embodiment of the disclosure, the pre-defined period of time is at least 24 hours.

In an embodiment of the disclosure, the mixer for mixing the dry powder and water is a shear mixer.

It is to be understood that the aspects and embodiments of the disclosure described above may be used in any combination with each other. Several of the aspects and embodiments may be combined together to form a further embodiment of the disclosure.

The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description.

BRIEF DESCRIPTION OF THE ACCOMPANYING FIGURES

The novel features and characteristics of the disclosure are set forth in the appended description. The disclosure itself, however, as well as a preferred mode of use, further objectives and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying figures. One or more embodiments are now described, by way of example only, with reference to the accompanying figures wherein like reference numerals represent like elements and in which:
FIG.1 is an exemplary embodiment of a building material, where the building material is a wallboard, in accordance with an embodiment of the present disclosure.

FIG.2 is a flowchart depicting method of manufacturing the building material of FIG.1, in accordance with an embodiment of the disclosure.

The figures depict embodiments of the disclosure for purposes of illustration only. One skilled in the art will readily recognize from the following description that alternative embodiments of the methods illustrated herein may be employed without departing from the principles of the disclosure described herein.

DETAILED DESCRIPTION

The foregoing has broadly outlined the features and technical advantages of the present disclosure in order that the detailed description of the disclosure that follows may be better understood. Additional features and advantages of the disclosure will be described hereinafter which form the subject of the description of the disclosure. It should also be realized by those skilled in the art that such equivalent system and method do not depart from the scope of the disclosure. The novel features which are believed to be characteristic of the disclosure, as to method of operation, together with further objects and advantages maybe better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the present disclosure.

In the present document, the word "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any embodiment or implementation of the present subject matter described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments.

While the disclosure is susceptible to various modifications and alternative forms, specific embodiment thereof has been shown by way of example in the figures and will be described in detail below. It should be understood, however that it is not intended to limit the disclosure to the particular forms disclosed, but on the contrary, the disclosure is to cover all modifications, equivalents, and alternative falling within the scope of the disclosure.

The terms “comprises”, “comprising”, or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a method that comprises a list of acts does not include only those acts but may include other acts not expressly listed or inherent to such method. In other words, one or more acts in a method proceeded by “comprises… a” does not, without more constraints, preclude the existence of other acts or additional acts in the method.

Embodiments of the present disclosure disclose composition of a building material, where the building material may be a wallboard. The wallboard is generally used in the building industry to define structural materials capable of being attached to wall or ceiling support structure and capable of receiving a decorative finish or design. Gypsum based wallboard products have been the standard of the industry, having gained acceptance due to their availability and their generally adequate performance in the field. However, manufacturing of the gypsum wallboard involves large amount of energy usage and thus high related costs. Further, the gypsum wallboard is also responsible for emission of greenhouse gases having negative impact on the environment.

The present disclosure described herein discloses a building material or a wallboard made such that it is light weight and requires minimum energy for manufacturing. The wallboard of the present disclosure eliminates the most energy intensive processes in the manufacture of gypsum wallboard such as gypsum drying, calcining, hot water, and board drying. Thus, the wallboard of the present disclosure, formed from non-calcined materials or minimal use of calcined materials and industrial wastes which are plentiful and safe react naturally to form a strong wallboard.

In the following detailed description, embodiments of the disclosure are explained with reference of accompanying figures that form a part hereof, and in which are shown by way of illustration specific embodiments in which the disclosure may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the disclosure, and it is to be understood that other embodiments may be utilized and that changes may be made without departing from the scope of the present disclosure. The following description is, therefore, not to be taken in a limiting sense.

FIG.1 is an exemplary embodiment of a building material, wherein the building material is a wallboard (100). The terms ‘wallboard’ and ‘building material’ are interchangeably used in the description of the present disclosure.
In an embodiment, composition of the wallboard (100) is disclosed. In one embodiment, the wallboard (100) be provided with paper on at least one side. The paper may receive coatings such as paint and other forms of decoration. In a preferred embodiment, the paper may be provided on both sides of the wallboard (100).

The wallboard (100) may be composed of a binder and fillers. The binder may be formed by combining calcium aluminate cement or Carbon fly ash, steel slag, calcium carbonate and calcium sulfate hemihydrate combined with various additives. The binder may be composed of these materials within a definite weight range. In an embodiment, the binder may be composed in weight percentage of calcium aluminate cement of about 15% to 35%,steel slag of about 5% to 50%,calcium sulfate hemihydrate of about 1% to 10%and calcium carbonate of about 1% to 40%.The selected binder materials may be mixed together with the fillers to form the wallboard (100).The steel slag used in the binder may be industrial waste which is abundantly available in a steel industry. In an embodiment, the steel slag may be in a powder form. In another embodiment, the steel slag may be in a granular form. In case of the steel slag being in a granular form, the size may be such that the granular steel slag passes completely through a 600µm sieve. In an embodiment, the calcium carbonate used in the binder may have a particle size of about 4 micron to 50 micron. In an embodiment, the fillers added to form the wallboard (100) may be selected from the group consisting of microspheres, saw dust, perlite and vermiculite.

Further, the additives are added to the binder to enrich the properties of the binder. In an embodiment, the additives may be added to the binder to control rheology and setting time of the binder. The additives that are used to control rheology includes polycarboxylate ethers, lignosulfonates, polyethylene glycols etc. Furthermore, the additives to control setting time of the binder includes borax, citric acid or alkali metal salts of citric acid etc. In an embodiment, the additives may be added in the range of about 0.1% to 4% to the binder.

The above cementitious composition may generally be used to obtain quick setting, that may be used for a variety of applications in which rapid hardening and attainment of early strength is desirable. In the present disclosure, the cementitious compositions using steel slag waste is used to make wallboard (100) which may exhibit high moisture durability for use in wet and dry locations in buildings. In an embodiment, precast concrete products such as cement boards are made under conditions which provide a rapid setting of the cementitious mixture so that the wallboards may be handled soon after the cementitious mixture is poured into a stationary or moving form or over a continuously moving belt.

In an embodiment, ettringite is formed during the setting of the wallboard (100). Ettringite is a compound of calcium aluminum sulfate having the formula:
Ca6AI2(SO4)3.32H2O
or alternatively 3CaO.Al2O3.3CaSO4.32H2O

In general, the composition of ettringite may be written as:
Ca6X2Y(OH)12.24-32 (H2O)
Where X = Al, Fe (III), Si(IV), Y= Sulfate, Carbonate, Borate, Hydroxide

Ettringite forms as long or medium needle-like crystals and provides rapid early strength to boards or any precast products, so that they may be handled soon after being poured into a mold or over a continuous casting and forming belt. In the present disclosure, it may be perceived that the wallboard (100) casted become hard due to the formation of ettringite. Reactive alumina for the formation of ettringite may be provided by high alumina cement, lime is provided by the added steel slag, and sulfate is provided by added hemihydrate.

In an embodiment, apart from the aforementioned composition of the binder and additives, few more additives may be added to increase dissolution rate of alumina and to control the rate of ettringite formation so that enough time is available for the formation of wallboard (100). Further, since the formation of ettringite takes place immediately after the addition of water, it may gel up quickly resulting in loss of workability of the mix. Hence retarders may be added to prevent the loss of workability. In an embodiment, the retarders added may include sodium citrate and sodium tetra borate.

Further, the wallboard (100) includes fibers such as but not limited to biofibers, nylon, glass and cellulose. In an embodiment, the fibers are added in the range of about 1% to 15%. Also foaming agents or surfactants are added to decrease the overall weight of the product. The wallboard further includes accelerators which may be selected from the group consisting of compounds of lithium such as lithium carbonate, lithium nitrate, lithium hydroxide. In another embodiment, the accelerators may be chromium based compounds such as but not limited to potassium chromate. The wallboard (100) also includes water reducing agents and foaming agents. In an embodiment, the water reducing agents may be polycarboxylate ethers, lingosulfonates etc., and are added in the range of about 0.1% to 3%. In an embodiment, the foaming agents may include hydrogen peroxide and sodium lauryl sulfate. The foaming agents are added in the range of about 0.1% to 3%.

Referring now to FIG.2, it illustrates a flowchart which includes one or more blocks illustrating a method of manufacturing the wallboard (100).

As shown at block 101, the method of manufacturing the wallboard (100) firstly involves mixing the binder in dry form in a blender to form a dry powder. The binder may be composed in weight percentage of calcium aluminate cement of about 15% to 35%,steel slag of about 5% to 50%,calcium sulfate hemihydrate of about 1% to 10%, calcium carbonate of about 1% to 40% and additives. Further, as shown at 102, the a pre-determined amount of water may be added to the dry powder in a mixer to form a slurry. In an embodiment, the mixer employed for mixing the dry powder with water may be a shear mixer.

The slurry is then casted in a mould as indicated at step 103. Further, as shown at step 103, the mould may be subject to vibration. In an embodiment, the vibration applied may be electromagnetic vibration, ultrasonic vibration or mechanical vibration. As shown at block 104, the cast in the steel mould may be allowed to cure for a pre-defined period of time. In an embodiment, the pre-defined period of time may be at least 24 hours. The cast so obtained may in turn be converted in to wallboards (100) of required dimension.

The wallboard (100) so obtained is lightweight and strong. Further, the wallboard (100) manufactured by the method of present disclosure eliminates the emission of greenhouse gases.

Examples
Sl.
No. CAC LD Slag POP MCC PCE SC B LC SLS SPA Fiber H2O2
(ml) Water Comp.
Strength
(Mpa) Weight of 2X2 Board
1 450 300 50 200 5 6 0 1 1 2 3 0 270 23.8
(24 Hr) 6.2 kgs
2 350 400 50 200 5 6 0 1 1 2 3 0 270 25.0
(24 Hr) 6.2 kgs
3 250 500 50 200 5 6 0 1 1 2 3 0 270 19.7
(24 Hr) 5.9 Kgs
4 250 500 50 200 5 6 0 1 1 2 3 50 270 1.2
(24 Hr) Broke
5 250 500 50 200 5 6 0 1 1 2 3 25 270 5.0
(24 Hr) 3.5 kgs
6 150 600 50 200 5 6 0 1 1 2 3 15 270 Did not set
7 200 400 50 350 5 8 1 1 1 2 12 0 270 10.2
(24 Hr) 3.9 kgs

In the above table, following abbreviations have been used –

CAC- Calcium Aluminate Cement: LD Slag- Steel slag (100% passed through 600 µm sieve), POP- Calcium sulfate Hemihydrate, MCC- Micro calcium carbonate, PCE- Polycarboxylate ether powder, SC – Sodium Citrate, B- Borax, LC – Lithium Carbonate, SLS- Sodium Lauryl Sulfate, SPA- Sodium poly acrylate, H2O2- Hydrogen peroxide.

The table shows different examples of various materials that are added to form a wallboard (100). The table also indicates properties of the wallboard so obtained in terms of strength and weight of the wallboard (100). Considering one of the examples, as in serial number 7, 200 units of CAC may be mixed with 400 units of LD slag, 50 units of POP, 350 units of MCC, 5 units of PCE, 8 units of SC, 1 unit of Borax, 1 unit of LC, 1 unit of SLS, 2 units of SPA, 12 units of fiber to form a dry powder. Further, 270 ml of water may be added to the resulting dry powder to form a slurry. The slurry may then be cast in a mould, vibrated in the mould and allowed to be cured in the mould for about 24 hours. The resulting wallboard (100) has a strength of about 10.2 Mega Pascal (MPa) and a 2X2 wallboard (100) that may be cut out, has a weight of 3.9 kg.

Referral numerals:

Features Numerals
100 Building material/Wallboard
101-104 Flowchart blocks

Equivalents

With respect to the use of substantially any plural and/or singular terms herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. The various singular/plural permutations may be expressly set forth herein for sake of clarity.

It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as "open" terms (e.g., the term "including" should be interpreted as "including but not limited to," the term "having" should be interpreted as "having at least," the term "includes" should be interpreted as "includes but is not limited to," etc. It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases "at least one" and "one or more" to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles "a" or "an" limits any particular claim containing such introduced claim recitation to inventions containing only one such recitation, even when the same claim includes the introductory phrases "one or more" or "at least one" and indefinite articles such as "a" or "an" (e.g., "a" and/or "an" should typically be interpreted to mean "at least one" or "one or more"); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of "two recitations," without other modifiers, typically means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogous to "at least one of A, B, and C, etc." is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., "a system having at least one of A, B, and C" would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances where a convention analogous to "at least one of A, B, or C, etc." is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., "a system having at least one of A, B, or C" would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase "A or B" will be understood to include the possibilities of "A" or "B" or "A and B."

While various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims.