DESC:The disclosure provides a cured building material. Particularly, the disclosure relates to a white cement building material. More particularly the disclosure relates to a fiber reinforced white cement building material.

DESCRIPTION OF THE RELATED ART
Conventional suspended ceiling tile is typically made of gypsum boards that are relatively light in weight or, low in density. This low weight is advantageous for manufacturing, shipping, handling and installation reasons. However, low density conventional ceiling tile frequently has the disadvantage of being relatively soft and fragile such that it is easily damaged in shipping, handling, and installation. Another major problem encountered with gypsum boards are they are prone to sagging in environment with high moisture. While it can be waterproofed through covalent waterproofing, if the waterproofing layer is punctured, water will cause the gypsum board to swell and eventually disintegrate requiring replacement. Moreover water proofing adds to the cost of the product. Moreover, gypsum by nature is a porous, lightweight substance that allows mold to grow. Hence, it is not used for rooms expected to have high humidity, primarily kitchens, bathrooms and laundry rooms.
An alternate to the gypsum boards is fiber reinforced cement boards. Fiber reinforced cement products such as building sheets or boards have been long used for buildings. Typical fiber reinforced cement board is made of approximately 40-60% of cement, 20-30% of fillers, 8-10% of cellulose, 10-15% of mica. However, fiber reinforced cement products tend to be heavy, limiting their use. Specifically limiting the use of these fiber reinforced cement products in ceiling applications. Cement boards are also not aesthetically appealing and often require additional layers of paint.
Thus, there remains a need for a cost-effective fiber reinforced cement building material that is light weight but has more damage resistance and sag resistance than is commonly found in prior art compositions. Such fiber reinforced cement building material should be aesthetically appealing and should be cost effective to produce.

SUMMARY
A cured building material is disclosed. The cured building material comprising a white cement in a range of 15-30% (w/w), fibers in a range of 5-18% (w/w) wherein a majority of the fibers have an aspect ratio of approximately 0.5: 1, a hydrophobic polymer in a concentration of at least 0.2% (w/w) and a filler in a form of fine aggregates having concentration in a range of 50-65% (w/w).

BRIEF DESCRIPTION OF DRAWINGS
FIG. 1-7 illustrates comparative results of the simulation conducted for gypsum sheets (known in the art) and white cement based sheets (in accordance with an embodiment of present disclosure).

DETAILED DESCRIPTION
For the purpose of promoting an understanding of the principles of the invention, reference will now be made to embodiments 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 disclosed process, and such further applications of the principles of the invention therein being contemplated as would normally occur to one skilled in the art to which the invention relates.
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.
Reference throughout this specification to “one embodiment” “an embodiment” 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 one embodiment”, “in an embodiment” and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment.
Throughout this specification the concentration has been expressed in terms of weight/weight (w/w) percent of the dry weight of the cured building material.
The present disclosure provides a cured building material (fiber reinforced white cement building material). Specifically, the disclosure provides a cured building material comprising white cement, fibers, hydrophobic polymers and filler in a form of fine aggregates.
The disclosure provides a cured building material comprising a white cement in a range of 15-30% (w/w); fibers in a range of 5-18% (w/w) wherein majority of the fibers have an aspect ratio of approximately 0.5: 1; a hydrophobic polymer in a concentration of at least 0.2% (w/w); and a filler in a form of fine aggregates having concentration in a range of 50-65% (w/w).
White cement functions as a “hydraulic binder”. Use of white cement also provides an aesthetical quality to the cured building material allowing it to be used in indoor applications such as false ceiling.
The fibers in the cured building material include but are not limited to cellulose fibers, glass fibers, synthetic fibers or combination thereof.
In accordance with an embodiment, the cured building material comprises of both cellulose fibers and glass fibers. The amount of cellulose fibers are in the range of 3 to 12 % (w/w) and the amount of glass fibers are in the range of 2 to 5 % (w/w). In accordance with an embodiment, the cellulose fibers are in the form of paper pulp.
In accordance with an aspect, the fibers in the cured building material are short fibers or flakes having an aspect ratio (length to width ratio) of approximately 0.5 : 1.
In accordance with an embodiment, the cured building material comprises of both short fibers and long fibers. In accordance with an embodiment, at least 80% of the fibers are short fibers. Shorter fibers allow even mixing of the fibers in the building material prior to curing, i.e., shorter fibers or flakes allow the fibers to be homogeneously dispersed throughout the building material in order to maximize the beneficial properties imparted by the fibers.
In accordance with an embodiment, the filler includes but are not limited to perlimix, perlite, dolomite, amorphous silica, diatomaceous earth, rice husk ash, blast furnace slag, granulated slag, steel slag, mineral oxides, mineral hydroxides, clays or mixtures thereof.
The filler in the cured building material are present in a range of 50 to 65 % (w/w). In accordance with an embodiment, the filler is perlimix.
In accordance with an altermate embodiment, the filler includes a combination of perlimix along with other filler selected from the group of perlite, dolomite, amorphous silica, diatomaceous earth, rice husk ash, blast furnace slag, granulated slag, steel slag, mineral oxides, mineral hydroxides, clays or mixtures thereof.
In the embodiment, where a combination of perlimix with other filler is used, the amount of the perlimix is in the range of 10 to 15 % (w/w).
The filler such as perlimix have low densities and allow the weight of the cured building material to be reduced allowing it to be used in applications that require lighter building materials such as false ceiling applications.
In accordance with an embodiment, the hydrophobic polymer is vinnapas 8034H manufactured and sold by Wacker Chemie AG. The hydrophobic polymer allows the cured building material to be used in high moisture environments.
In accordance with an embodiment, the cured building material further comprises of other polymers in the range of 1 to 2% (w/w). Such polymers may include but are not limited to methyl cellulose, starch ether or a combination thereof.
In accordance with an embodiment, the cured building material further comprises of additives including but not limited to fire retardants, thickeners, pigments, colorants, plasticisers, dispersants, foaming agents, flocculating agents, density modifiers or mixtures thereof. Additives may be present in a range of 0.15 to 1 % (w/w).
The cured building material may be prepared from a waterborne mixture or slurry by any conventional process as would be known to a person skilled in the art such as the hatschek sheet process, mazza pipe process; magnani process; injection molding; extrusion; hand lay-up process; molding; casting filter pressure.
In accordance with an aspect, the cured building material may include:
White cement : 15 - 30 wt%
Fibers : 5 – 18 wt%
Filler (Fine Aggregates) : 50 – 65 wt%
Hydrophobic polymers: 0.2 – 0.8 wt%

By way of specific example, the cured building material may include:
White cement: 25-30 wt%,
Fine aggregates: 40 - 50wt%,
Paper pulp/Cellulose fibers: 3 – 12 wt%,
Perlimix: 10-15 wt%
Glass fibers -2-5 wt%,
Polymer: 1-2 wt%.

The following example(s) are exemplary and should not be understood to be in any way limiting.
Example 1:

Mixing Procedure (1kg batch size without water)
In a mixer container 270 gms of white cement, 180 gms of dolomite powder, 290 gm dolomite sand, 105gms perlimix, 40gm glass fibers, 97gm cellulose fiber/paper pulp and 13gm polymer were dry mixed for 10 minutes in a mixture. Subsequently 750 gms of water was added to the mixture and mixed for another 10 minutes in a mortar mixture to obtain a uniform paste.

Procedure for preparing board
Vacuum press equipment is washed and dried. A filter cloth (5µm size) and a plastic sheet is cut to the size of frame (400mm x 300mm and 600mm x 600mm depending on the size of the board to be made). The filter cloth is placed on perforated sheet in the vacuum press and the stainless steel frame is placed over it. The mixed paste as obtained from earlier is spread uniformly within the stainless frame with the help of a trowel and the cut plastic sheet is then placed on the board. The system is then closed and pressure of about 20 torr (range: 20 -60 torr) is applied manually for 2 to 5 minutes along with vacuum. The board is then removed from the press and set on a wooden frame along with filter cloth and dried at room temperature ( 20-35?C) or autoclaved for curing.

Composition:
Two white cement building materials were prepared using the above method having the following compositions:

Sample 1:
White cement: 27 wt %
Fine aggregates: 47 wt %
Cellulose/paper pulp: 9.7 wt %
Perlimix: 10.5 wt %
Glass fiber : 4.0 wt %
Polymer: 1.3 wt %

Sample 2:
White cement: 25 wt %
Fine aggregates: 49 wt %
Cellulose/paper pulp: 8 wt %
Perlimix: 12.2 wt %
Glass fiber- 4.0 wt %
Polymer: 1.3 wt %

(The compositions are based on dry weight post curing)

Table 1: Compares the breaking load/ flexural strength and water absorption of gypsum board and Sample 1 and Sample 2 of the cured building material.

Properties Gypsum Board Developed sample 1 Developed sample 2 Requirement as per the IS:2095(part-1)-1996 (Base board, 9.5mm thick)
Breaking Load (Longitudinal Direction) 279.5 N 226.2 N 191.2 N 180 Min. N
Breaking Load (Transverse Direction) 134.5 N 181.2 N 151 N 125 Min. N
Water Absorption % by wt 65.9 30.7 29.5 Standard followed: IS:-2542(part-2/sec-1 to8)-1981 (no specific values in standard)

It is observed that the water absorption property of the cured building material is reduced by approximately 50 %.

Example 2: Simulation conducted for known gypsum boards and white cement based sheets (cured building material)
White cement based sheets (boards/ cured building material) were prepared in accordance with the disclosure. Further, gypsum sheets (commercially available normal grade gypsum boards) were used. Small wooden structure was made with ceiling grid for fixing the boards having a size of 400mm x 300 mm. The white cement based boards have been fixed in half portion and the gypsum boards in the other half portion of structure as shown in figure 1. As shown in figure 2, the gypsum sheets appear dotted while the white cement based sheets appear plain.
Dotted sheets of gypsum and plain sheet of white cement are shown in figure 2.
Water storage and sprinkle pipes were also arranged as shown in figure 3, just above the fixed ceiling board (having both the gypsum sheets and white cement based sheets) for continuous water drop falling over sheets in the wooden structure.
The main objective of simulation of both sheets is to observe and compare durability of both the boards. The results are summarized as follows:-
a) Identify any fungus growth on sheets
To observe comparative fungus growth, both the sheets were kept in similar conditions and observed after an interval of 10 and 18 days. Simulation observation results of white cement based vs gypsum boards after 10 (shown in figure 3) and 18 days (shown in figure 4 and 5).
It is clear from the Figure 3-5 that fungus growth is very high on gypsum board whereas no fungus growth is found on white cement based board, although wetting of both the boards is observed after 10 and 18 days of simulation results.

b) Degradation/ Shape deformation of sheets
To prevent leakage of water from the gypsum sheets and white cement based sheets an adhesive is used such as M-seal. Rear view of both the sheets is illustrated in figure 6 (6A and 6B). After simulation, shape deformation in the form of bending is observed in the gypsum sheet (as illustrated in figure 7A). The same is not observed in the white cement based sheet (as illustrated in figure 7B).

SPECIFIC EMBODIMENTS ARE DESCRIBED BELOW
A cured building material comprising a white cement in a range of 15-30% (w/w), fibers in a range of 5-18% (w/w) wherein a majority of the fibers have an aspect ratio of approximately 0.5: 1, a hydrophobic polymer in a concentration of at least 0.2% (w/w) and a filler in a form of fine aggregates having concentration in a range of 50-65% (w/w).
Such cured building material(s), wherein the filler is perlimix.
Such cured building material(s), wherein the filler further comprising any of perlite, dolomite, amorphous silica, diatomaceous earth, rice husk ash, blast furnace slag, granulated slag, steel slag, mineral oxides, mineral hydroxides, clays or mixtures thereof.
Such cured building material(s), wherein the perlimix is in a range of 10-15% (w/w).
Such cured building material(s), further comprising 1-2% (w/w) of a polymer.
Such cured building material(s), wherein the polymer is methyl cellulose or starch ether or a combination thereof.
Such cured building material(s), further comprising of 0.15- 1% (w/w) of an additive.
Such cured building material(s), wherein the additive is selected from retardants, thickeners, pigments, colorants, plasticizers, dispersants, foaming agents, flocculating agents, density modifiers or mixtures thereof.

INDUSTRIAL APPLICABILITY
The cured building material disclosed above is cost-effective low density fiber reinforced white cement building material. The cured building material is light weight with improved damage resistance and sag resistance as compared to known boards. Such cured building material is aesthetically appealing and economical to produce. Further, such material can be used in indoor applications such as false ceiling. Furthermore, the cured building material can be used in high moisture environments. The cured building material is superior to the known boards in respect of the following properties: fungal attack resistance, water resistance, high durability, aesthetic appearance, weather resistance, eco-friendly, light weight and useful for arresting leakage/seepage.
,CLAIMS:WE CLAIM:

1. A cured building material comprising:
a white cement in a range of 15-30% (w/w);
fibers in a range of 5-18% (w/w) wherein a majority of the fibers have an aspect ratio of approximately 0.5: 1;
a hydrophobic polymer in a concentration of at least 0.2% (w/w); and
a filler in a form of fine aggregates having concentration in a range of 50-65% (w/w).

2. A cured building material as claimed in claim 1, wherein the fibers are cellulose fibers or glass fibers or a combination thereof.

3. A cured building material as claimed in claim 1, wherein the filler is perlimix.

4. A cured building material as claimed in claim 3, wherein the filler further comprising any of perlite, dolomite, amorphous silica, diatomaceous earth, rice husk ash, blast furnace slag, granulated slag, steel slag, mineral oxides, mineral hydroxides, clays or mixtures thereof.

5. A cured building material as claimed in claim 4, wherein the perlimix is in a range of 10-15% (w/w).

6. A cured building material as claimed in claim 1, further comprising 1-2% (w/w) of a polymer.
7. A cured building material as claimed in claim 6, wherein the polymer is methyl cellulose or starch ether or a combination thereof.

8. A cured building material as claimed in claim 1 or 6, further comprising of 0.15- 1% (w/w) of an additive.

9. A cured building material as claimed in claim 8, wherein the additive is selected from retardants, thickeners, pigments, colorants, plasticizers, dispersants, foaming agents, flocculating agents, density modifiers or mixtures thereof.

Dated this 22nd April of 2013

Aparna Kareer
Of Obhan & Associates
Agent for the Applicant
Patent Agent No. 1359