FORM 2
THE PATENTS ACT, 1970
(39 OF 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See Section 10 and Rule 13)
A REINFORCED CEMENT COMPOSITION
RELIANCE INDUSTRIES LIMITED
an Indian Company of 3rd Floor, Maker Chamber-IV, 222, Nariman froint, Mumbai-400021.
Maharashtra, India.
Inventors:
1. GAJELLI Chandramouli Gangaram
2. KELKAR Anil Krishna
3. GURUDATT Krishnamurthy
4. NIKAM Suresh Bhanudas
5. BHANGALE Vikas Kadu
6. ARORAArun
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED.

FIELD OF THE DISCLOSURE
The present disclosure relates to a cement composition. More particularly, the present disclosure relates to a reinforced cement composition.
BACKGROUND
Cement has traditionally been used as a building and construction material, as it sets and hardens independently and binds together different materials. Cement has been blended with multifarious substances such as lime, gravel, volcanic ash, pulverized brick and concrete in order to provide benefits such as durability and cost-efficiency.
Cement has also been reinforced with asbestos fibers due to the advantages offered, such as cost efficiency, fire-resistance, water tightness and light weight. Asbestos, however, has been found to be carcinogenic and a majority of countries have laid down several restrictions regarding its use.
Cement compositions with fillers and/ or reinforcing substances such as wood pulp and silica have also been explored. However, during the autoclave curing of cement-wood pulp based products, the moisture that is characteristic of the autoclaving process, is absorbed by the wood, causing It to swell and lose its physical integrity to a certain extent and become weak. The physical integrity and strength of the cement-wood pulp products is hampered, thus prejudicing the quality of the product. Besides, the cellulosic fibers are inherently rigid thereby providing lesser bending strength to the cementicious sheet.
Therefore, there exists a need to provide an effective means to counter the hydrophilicity of wood pulp in order to facilitate the preparation of cement-wood pulp based products with improved properties such as durability and bending strength.
OBJECTS
Some of the objects of the present disclosure, which at least one embodiment is able to achieve, are discussed herein below.
It is an object of the present disclosure to provide a reinforced cement composition.

It is another object of the present disclosure to provide cement products that are prepared from the reinforced cement composition.
It is still another object of the present disclosure to provide cement products which are capable of being cured by the autoclave process.
It is yet another object of the present disclosure to provide cement products which are economical and environment friendly.
It is still another object of the present disclosure to provide a process for the preparation of cement products.
It is yet another object of the present disclosure to ameliorate one or more problems of the prior art or to at least provide a useful alternative.
Other objects and advantages of the present disclosure will be more apparent from the following description which is not intended to limit the scope of the present disclosure.
SUMMARY
The present disclosure provides a reinforced cement composition comprising:
i. cement in an amount ranging from 50 to 60 % of the total mass of the composition;
ii. micro-silica in an amount ranging from 35 to 45 % of the total mass of the composition;
iii. at least one polymeric fiber in an amount ranging from 0.01 to 1 % of the total mass of the composition; and
iv. wood pulp in an amount ranging from 0.1 to 10 % of the total mass of the composition.
In accordance with the cement composition of the present disclosure, the polymeric fiber is polyester fiber.

In accordance with the cement composition of the present disclosure, the polyester is at least one selected from the group consisting of Polyethylene terephthalate(PET), Polylactic acid (PLA), Polyglycolic acid (PGA), Polycaprolactone (PCL), Polyhydroxyalkanoate (PHA), Polyhydroxybutyrate (PHB), Polyethylene adipate (PEA), Polybutylene succinate(PBS), Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), Polybutylene terephthalate(PBT), Polytrimethylene terephthalate (PTT), Polyethylene naphthalate(PEN) and Vectran.
The cement composition of the present disclosure is adapted to be molded into products that withstand the autoclave curing procedure.
The present disclosure further provides a process for the preparation of cement products; said process comprising:
i. preparing a reinforced cement composition comprising cement, micro-silica, at least one polymeric fiber and wood pulp;
ii. molding said composition to yield at least one molded cement product;
iii. humid curing said molded cement product at humidity ranging from 50% to 90%, for a time period ranging from 12 hours to 48 hours to obtain humid cured cement product; and
iv. subjecting said humid cured cement product to autoclave curing at a temperature ranging from 150 to 200 °C, at a pressure ranging from 5 to 15 bars in the presence of at least one medium to obtain the cement product,
said cement product being characterized by flexural strength ranging from 55 to 65 kg/cm .
In accordance with the process of the present disclosure, the cement product is at least one selected from the group consisting of boards, plinths, panels, slabs, columns, sheets, blocks, boards and shafts.

In accordance with the process of the present disclosure, the medium is at least one selected from the group consisting of steam and water.
The present disclosure still further provides an article prepared from the reinforced cement composition; said article being selected from the group consisting of wall panels, door panels, partition boards, building boards, floor tiles and siding planks.
DETAILED DESCRIPTION
Cement compositions can be cured by different methods such as air curing or autoclave curing. Autoclave curing is preferred than air curing as products cured by the former process are more durable and dimensionally stable. Further, the high moisture content during autoclave curing increases the curing speed and the final strength of the product. Cement based compositions comprising wood pulp and other additives however, are unable to show enhanced benefits after autoclaving due to the hydrophilicity of the wood pulp. The present disclosure, therefore, proposes replacing wood pulp with at least one polymeric fiber. The present disclosure provides a reinforced cement composition comprising cement, micro-silica, at least one polymeric fiber and wood pulp; in order to mitigate the afore-stated quandary.
The composition provided by the present disclosure contains cement as the base material in an amount ranging between 50 and 60 % of the total mass of the composition. The composition further contains micro-silica in an amount ranging between 35 and 45 % of the total mass of the composition. Micro-silica is included in the composition of the present disclosure in order to improve the compressive strength, bond strength and abrasion resistance of the products prepared from the composition.
The present composition discloses employing at least one polymeric fiber in place of wood pulp in order to avoid the drawbacks associated with autoclave curing wood pulp containing composition. The wood pulp is at least partially substituted with the polymeric fiber(s) such that the proportion of substitution of wood pulp with the polymeric fiber(s) ranges from 3: 1 to 6: 1. In one embodiment, the polymeric fiber of

the present disclosure is polyester fiber. The polyester is at least one selected from the group that includes but is not limited to Polyethylene terephthalate (PET), Polylactic acid (PLA), Polyglycolic acid (PGA), Polycaprolactone (PCL), Polyhydroxyalkanoate (PHA), Polyhydroxybutyrate (PHB), Polyethylene adipate (PEA), Polybutylene succinate (PBS), Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), Polybutylene terephthalate (PBT), Polytrimethylene terephthalate (PTT), Polyethylene naphthalate (PEN) and Vectran. The present composition contains the polymeric fiber(s) in an amount ranging from 0.1 to 1 % of the total mass of the composition.
The amount of wood pulp in the composition ranges from 0.1 to 10 % of the total mass of the composition.
The present disclosure further provides a process for the preparation of cement products prepared from the afore-stated reinforced cement composition. The product of the present disclosure is at least one selected from the group that includes but is not limited to boards, plinths, panels, slabs, columns, sheets, blocks, boards and shafts. The process steps include preparing a reinforced cement composition comprising cement, micro-silica, polymeric fiber(s) and wood pulp. The composition is then molded to yield molded cement products that are subjected to humid curing. Humid curing is carried out at humidity ranging from 50% to 90%, for a time period ranging from 12 hours to 48 hours to obtain humid cured cement product which is then subjected to autoclave curing. The process of autoclave curing is carried out at a temperature ranging from 150 to 200 °C, at a pressure ranging from 5 to 15 bars in the presence of at least one medium to obtain the cement products. The medium used for autoclave curing is at least one selected from the group that includes but is not limited to steam and water.
The present disclosure still further provides an article prepared from the afore-stated reinforced cement composition that is selected from the group that includes but is not limited to wall panels, door panels, partition boards, building boards, floor tiles and siding planks.

The autoclaved cured cement products obtained as a result of the present process are characterized by flexural strength ranging from 55 to 65 kg/cm . The composition of the present disclosure, after replacing a part of wood pulp with synthetic fiber(s), is more tolerant towards the autoclave curing procedure.
The present disclosure will now be discussed in the light of the following non-limiting embodiments:
Example 1: Process for the preparation of a cement product according to the present disclosure is presented herein below (replacement of wood pulp by polymeric fiber is in the ratio 3:1).
For preparing a 100 kg batch, 56.4 kg of cement, 38.2 kg of micro-silica and 0.3 kg of 1,5 d, 6 mm polyethylene terephthalate fibers (polyester fibers) were dry mixed followed by adding 5.1 kg of refined 'soft wood pulp' in water. An excess of water was added to make slurry of the admixture, which was later poured into a mold having the following dimensions: 200 mm length x 78 mm width x 6 mm thickness and pressed in a hydraulic press, at a force of 10 - 14 tons to form a panel. The panel was then humid cured for one day followed by autoclave curing at about 175 ± 5 °C for 10 hrs.
Example 2: Process for the preparation of a cement product according to the present disclosure (replacement of wood pulp by polymeric fiber is in the ratio 5:
1)
For preparing a 100 kg batch, 56.8 kg of cement, 38.4 kg of micro-silica and 0.3 kg of
1.5 d, 6 mm polyethylene terephthalate fibers were dry mixed followed by adding 4.5 kg of refined 'soft wood pulp' in water. An excess of water was added to make slurry of the admixture, which was later poured into a mold having the following dimensions: 200 mm length x 78 mm width x 6 mm thickness and pressed in a hydraulic press, at a force of 10 - 14 tons to form a panel. The panel was then humid cured for one day followed by autoclave curing at about 175 ± 5 °C for 10 hrs.

Example 3: Comparative example demonstrating an increased flexural strength upon the replacement of wood pulp with polymeric fibers
The cement products prepared in Example 1 and 2 were tested for flexural strength in Instron UTM (universal testing machine). The flexural strength of the afore-stated reinforced cement products was compared with the flexural strength of the cement products prepared with the same process but without replacement by the polymeric fiber. The results obtained are presented in Table 1.
Table 1. Flexural strength of products obtained from reinforced cement compositions and non-reinforced cement composition

Sr. Ingredient Without polymeric With polymeric With polymeric
No. Flexural strength fiber replacement fiber replacement (3:1) fiber replacement (5:1)
1 Cement 56 wt% 56.4 wt% 56.8 wt%
2 Micro-silica 38wt% 38.2 wt% 38.4 wt%
3 Wood pulp
(cellulose
fibers) 6wt% 5.1 wt% 4.5 wt%
4 Polyester fibers 0.3 wt% 0.3 wt%
5 Flexural strength MRA
(kg/cm2) 50.6 57 56.2
It is evident from the results that the flexural strength of the autoclave cured-reinforced cement products is greater than that of the autoclave cured-non-reinforced cement products. Therefore, replacement of a part of wood pulp with polymeric fibers increases the tolerance of the cement composition towards autoclave curing, which in turn positively affects the flexural strength of the resultant products.

While replacing wood pulp with polymeric fibers, in order to maintain the total weight constant 100%, balance weight percentage in both the cases was distributed in the cement and silica percent weights in 60:40 ratio (0.4% in cement and 0.2% in silica). Properties such as flexural strength are independent of such an incremental increase.
TECHNICAL ADVANCEMENT AND ECONOMIC SIGNIFICANCE
The present disclosure provides a reinforced cement composition that is capable of sustaining the autoclave curing process.
The present disclosure provides cement products prepared from the reinforced cement composition that have an improved flexural strength as compared to the products prepared from the non-reinforced cement composition.
The cement products prepared by using the reinforced composition of the present disclosure have improved bending strength and dimensional stability as compared to the products prepared from the non-reinforced compositions.
Throughout this specification the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.
The use of the expression "at least" or "at least one" suggests the use of one or more elements or ingredients or quantities, as the use may be in the embodiment of the invention to achieve one or more of the desired objects or results.
The numerical values given for various physical parameters, dimensions and quantities are only approximate values and it is envisaged that the values higher than the numerical value assigned to the physical parameters, dimensions and quantities fall within the scope of the invention and the claims unless there is a statement in the specification to the contrary.

While certain embodiments of the inventions have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Variations or modifications in the process or compound or formulation or combination of this invention, within the scope of the invention, may occur to those skilled in the art upon reviewing the disclosure herein. Such variations or modifications are well within the spirit of this invention. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the invention.

WE CLAIM:
1. A reinforced cement composition comprising:
i. cement in an amount ranging from 50 to 60 % of the total mass of the composition;
ii. micro-silica in an amount ranging from 35 to 45 % of the total mass of the composition;
iii. at least one polymeric fiber in an amount ranging from 0.01 to 1 % of the total mass of the composition; and
iv. wood pulp in an amount ranging from 0.1 to 10 % of the total mass of the composition.
2. The composition as claimed in claim 1, wherein said polymeric fiber is polyester fiber.
3. The composition as claimed in claim 3, wherein said polyester is at least one selected from the group consisting of Polyethylene terephthalate(PET), Polylactic acid (PLA), Polyglycolic acid (PGA), Polycaprolactone (PCL), Polyhydroxyalkanoate (PHA), Polyhydroxybutyrate (PHB), Polyethylene adipate (PEA). Polybutylene succinate(PBS), Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), Polybutylene terephthalate(PBT), Polytrimethylene terephthalate (PIT), Polyethylene naphthalate(PEN) and Vectran.
4. The composition as claimed in claim 1, adapted to be molded into products that withstand the autoclave curing procedure.
5. A process for the preparation of cement products; said process comprising:
i. preparing a reinforced cement composition comprising cement, micro-silica, at least one polymeric fiber and wood pulp;
ii. molding said composition to yield at least one molded cement product;

iii. humid curing said molded cement product at humidity ranging from 50% to 90%, for a time period ranging from 12 hours to 48 hours to obtain humid cured cement product; and
iv. subjecting said humid cured cement product to autoclave curing at a temperature ranging from 150 to 200 °C. at a pressure ranging from 5 to 15 bars in the presence of at least one medium to obtain the cement product.
said cement product being characterized by flexural strength ranging from 55 to 65 kg/cm .
6. The process as claimed in claim 5, wherein said cement product is at least one selected from the group consisting of boards, plinths, panels, slabs, columns, sheets, blocks, boards and shafts.
7. The process as claimed in claim 5, wherein said medium is at least one selected from the group consisting of steam and water.
8. An article prepared from the reinforced cement composition as claimed in claim 1; said article being selected from the group consisting of wall panels, door panels, partition boards, building boards, floor tiles and siding planks.