WO2021105824A1

WO2021105824A1 - An admixture composition for reducing water curing of cement concrete, plaster and methods of manufacturing thereof

Info

Publication number: WO2021105824A1
Application number: PCT/IB2020/060890
Authority: WO
Inventors: Natarajan RAMKUMAR; Natarajan VARADHARAJAN; Deepak Kumar PARIHAR; Abhishek Sinha
Original assignee: Navoday Sciences Private Ltd
Current assignee: Navoday Sciences Private Ltd
Priority date: 2019-11-28
Filing date: 2020-11-19
Publication date: 2021-06-03
Anticipated expiration: 2022-05-28

Abstract

The present invention discloses the formulation of an admixture that can be added to cement and sand mixture during plastering to reduce the water curing requirements of cement plaster. Specifically, the invention discloses formulation and method for manufacturing the admixture which reduces the water curing requirement of cement plaster without effecting the compressive strength of the same.

Description

AN ADMIXTURE COMPOSITION FOR REDUCING WATER CURING OF CEMENT CONCRETE, PUASTER AND METHODS OF MANUFACTURING

THEREOF

TITUE OF THE INVENTION

[001] The present invention relates to admixture composition for reducing the water curing requirements of cement plaster and concrete.

BACKGROUND OF INVENTION

[002] Water is the most consumed substance in the world; the second is concrete, which ordinarily contributes to significant further use of water resources. Although the industry does not yet possess comprehensive, global data of its water use, global water withdrawals are rapidly increasing. Beyond accurate tracking of water consumption, the industry needs innovative technologies that can help reduce water consumption, as water scarcity mounts as a looming threat to business survival.

[003] Concrete is combined mixture of construction material composed of hydraulic cement, sand, aggregates, additives and water. In general concrete includes a mixture of natural/artificial amount of sand (either gravel, or a crushed stone) which are bind together with hydraulic cement (Portland cement), water and various chemical admixtures or supplementary cementing materials. The water added to concrete or cement plaster plays two roles in concrete making. The first is to provide the required flow characteristics to the concrete mix, so that it can be shaped and formed. The second is to cure the concrete, i.e., to chemically react with cement to form calcium silicate hydrate, calcium aluminum hydrate and calcium hydroxide. The addition of additives in concrete or cement is done to enhance the performance or properties of concrete.

[004] Concrete composition disclosed in patent document US 10000414 comprises of hydraulic cement, an aggregate, an alkali metal salt consisting of halides, nitrites, acetates, sulfates in order to reduce internal relative humidity of hardened concrete. The patent discloses use of ultrafine calcium carbonate and highly reactive pozzolan for scavenging excess water. [005] Patent document JP 2015-140272 discloses an additive for concrete and a method for producing the additive comprising a functional material and a resin layer added to the functional material. The patent further describes a method for modifying the functional material at the softening temperature of a resin used or to a temperature higher or lower than the curing temperature.

[006] Another patent document, CN107053445 relates to the field of concrete curing and discloses a curing film for adding concrete to a water reducing agent, including a mulch film and a condensed film. The prior art teaches that the surface of the cement is moist and proper evaporation occurs for efficient hydration process.

[007] The additive formulations or admixtures disclosed in the prior art are used for reducing the internal relative humidity, the rate of water vapor emission and removal of excess water from the cementitious mix. The formulation describes the formation of curing film and also addition of the film to a water reducing agent for efficient hydration of water for effective curing process.

[008] In the light of above state-of-art, there is a requirement for effective formulation that lowers the water requirement during curing by reducing the time for curing without compromising on the compressive strength of the concrete. It is well known that Portland cement based cement and concrete needs to be cured with water for 28 days for proper development of strength.

OBJECTIVE OF THE INVENTION

[009] The primary objective of the present invention is to propose an admixture composition of the cement plaster for reducing water curing requirements of cement plaster and concrete.

[0010] Yet another objective of present invention is to propose the method for producing an admixture composition for reducing water curing needs of cement plaster.

[0011] These and other features and advantages of the present invention may be incorporated into certain embodiments of the invention and will become fully apparent from the following description or may be learned by the practice of the invention as set forth hereinafter. The present invention does not require that all the advantageous features and all the advantages described herein be incorporated into every embodiment of the invention.

SUMMARY OF THE INVENTION

[0012] Various embodiments of the invention relate to an admixture composition and method for manufacturing the admixture composition that can be added to cement and sand mixture or cement, sand and aggregate mixture during plastering in former case or concreting in later case to reduce the water curing needs of cement plaster or concrete without effecting the compressive strength of the cement plaster. The admixture formulation may comprise an alkali metal carbonate, an alkali metal sulfate, a thickening agent, a superabsorbent polymer, a tertiary amine and/or an air entraining agent.

DETAILED DESCRIPTION OF THE INVENTION

[0013] The following presents a simplified description of the invention in order to provide a basic understanding of some aspects of the invention. This description is not an extensive overview of the present invention. It is not intended to identify the key/critical elements of the invention or to delineate the scope of the invention. Its sole purpose is to present some concept of the invention in a simplified form.

[0014] 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.

[0015] Features that are described and/or illustrated with respect to one embodiment may be used in the same way or in a similar way in one or more other embodiments and/or in combination with or instead of the features of the other embodiments.

[0016] 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.

[0017] It is to be understood that the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise.

[0018] 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. The equations used in the specification are only for computation purpose.

[0019] The present invention relates to the formulation of admixture that can be added to cement and sand mixture during plastering to reduce water curing requirements of cement plaster. Further, the invention also proposes the method of preparing plaster admixture of the said formulation.

[0020] The present invention relates to the formulation of admixture that can be added to cement sand and aggregate mixture during concreting to reduce water curing requirements of cement concrete. Further, the invention also proposes the method of preparing concrete admixture of the said formulation.

[0021] The main embodiment of the present invention is an admixture composition to be added to cement and sand mixture for reducing the water curing requirements of cement plaster or cement concrete. The admixture composition proposed herein comprises of alkali metal carbonate, alkali metal sulfate, thickening agent, superabsorbent polymer, tertiary amine and/or air entraining agent.

[0022] The curing free admixture formulation proposed for cement or concrete herein comprises of an alkali metal carbonate in the range of 30% to 40% by weight. Preferably, the alkali metal carbonate may be calcium carbonate having a particle size in the range of 2-20 microns. Alternatively, the alkali metal carbonate may be selected from the group of sodium carbonate, potassium carbonate, barium carbonate and lithium carbonate. [0023] The admixture formulation proposed for cement or concrete herein comprises of an alkali metal sulfate in the range of 30%-49% by weight. Preferably, the alkali metal sulfate may be sodium sulfate having a solubility of more than 15%. Alternatively, the alkali metal sulfate may be selected from the group of calcium sulfate, potassium sulfate, barium sulfate and lithium sulfate.

[0024] The admixture formulation proposed for cement or concrete herein comprises of a thickening agent in the range of 0.2% to 1.5% by weight. Preferably, the thickening agent may be hydroxyl methylethyl cellulose or Bentonite. Alternatively, the thickening agent may be selected from the group of kaolin, metakaolin, montmorillonite, attapulgite, expanded shale, carboxymethyl cellulose or perlite.

[0025] The admixture formulation proposed for cement or concrete herein comprises of a superabsorbent polymer having particle size between 70-85 microns in the range of 0.1% to 1.5% by weight. Preferably, the superabsorbent polymer may be sodium polyacrylate. Alternatively, the superabsorbent polymer may be Polyacrylamide copolymer and other bio based super absorbent polymers, ethylene-maleic anhydride copolymer or polyvinyl alcohol copolymer.

[0026] The admixture formulation proposed for cement or concrete herein comprises of tertiary amines in the range of 0.1% to 2% by weight. Preferably, the tertiary amine may be triethanol amine or tri isopropanol amine. Alternatively, the tertiary amine may be the group of aliphatic amines like methylamine, di methylamine, diethylamine, tri ethanol amine, and tri isopropanol amine.

[0027] The admixture formulation proposed for cement or concrete herein comprises of an air entraining agent in the range of 0.01% to 0.8% by weight. Preferably, the air entraining agent may be sodium lauryl sulfate. Alternatively, the air entraining agent may be selected from the group alkyl polyglycol ethers, alkyl sulphates and alkyl sulphonates.

[0028] Another embodiment of the present invention is a method of manufacturing the admixture formulation. The method includes blending all the components in a high precision blender. During blending, the liquid component tri isopropanol amine (TIPA) is mixed with sodium sulfate separately. The mixture is then fed along with the other components into the blender. All the components are blended for approximately 3 to 10 minutes in the high precision blender.

[0029] After blending, the admixture is bagged and stored for further use. The admixture is mixed with Portland pozzolana cement and sand to make cement plaster, which is then used to make cement cubes. These cubes are demoulded after 24 hours and one set of cubes was kept for only another 24 hours of water curing and kept in air at room temperature (30 °C) and one set was immersed in water for curing for 28 days and tested for their compressive strength.

[0030] As per the exemplary embodiment, 50 kilograms of the proposed formulation of admixture are blended in a high precision blender for about 5 minutes. Before blending, one of the liquid component tri isopropanol amine (TIP A) is mixed with sodium sulfate separately and then fed along with the other components into the blender in accordance with the weights depicted in Table 1 below:

Table 1. Admixture formulation

[0031] After mixing the above-mentioned composition for 5 minutes in the blender the mixture was bagged. The blended 500grams of admixture powder is then mixed along with 5kgs of Portland pozzolana cement and 35kgs of manufactured sand to make cement plaster. Further, water is added in sufficient quantity to obtain a workable cement plaster and the mix is then used to make 70mm cubes. A total of 24 cubes were made, 9 cubes were kept in water for 24 hrs for water curing after demoulding and then kept at room temperature for air curing for 26 days. The other 9 were immersed in water for 27 days for water curing. [0032] The compressive strength of concrete cubes was tested with 1% admixture and without additive at 1, 3, 7 and 28 days and is tabulated below (Table 2):

Table 2: Compressive strength results with Plaster additives

[0033] As seen above, the proposed formulation of admixture increases the compressive strength of cement plaster. Moreover, the present invention reduces the need of water curing in cement plaster. [0034] Although the embodiments herein are described with various specific embodiments, it will be obvious for a person skilled in the art to practice the invention with modifications. However, all such modifications are deemed to be within the scope of the invention.

Claims

CLAIMS:

1. An admixture formulation consisting of:

• 30% to 49% by weight of an alkali metal carbonate;

• 30% to 49% by weight of an alkali metal sulfate with minimum solubility of 15%;

• 0.2% to 1.5% by weight of a thickening agent;

• 0.2% to 1.5% by weight of a superabsorbent polymer;

• 0.1% to about 2% by weight of a tertiary amine; and

• 0.01% to about 0.8% by weight of an air entraining agent.

2. The admixture formulation as claimed in claim 1, wherein the alkali metal carbonate may be calcium carbonate having an average particle size in range of 8- 20 microns.

3. The admixture formulation as claimed in claim 1, wherein the alkali metal sulfate is sodium sulfate.

4. The admixture formulation as claimed in claim 1, wherein the thickening agent is hydroxyl methylethyl cellulose or bentonite.

5. The admixture formulation as claimed in claim 1, wherein the tertiary amine is tri ethanol amine or tri isopropanol amine.

6. The admixture formulation as claimed in claim 1, wherein the air entraining agent is sodium lauryl sulfate.

7. The admixture formulation as claimed in claim 1, wherein the superabsorbent polymer is sodium polyacrylate.

8. The admixture formulation as claimed in claim 1, wherein the alkali metal carbonate is selected from the group of selected from the group of sodium carbonate, potassium carbonate, barium carbonate and lithium carbonate.

9. The admixture formulation as claimed in claim 1, wherein the alkali metal sulfate is selected from the group of selected from the group of calcium sulfate, potassium sulfate, barium sulfate and lithium sulfate.

10. The admixture formulation as claimed in claim 1, wherein the tertiary amine is selected from the group of the tertiary amine may be the group of aliphatic amines like methylamine, dimethylamine, diethylamine, triethanol amine, and tri isopropanol amine.

11. The admixture formulation as claimed in claim 1, wherein the thickening agent is selected from the group of the thickening agent may be selected from the group of kaolin, metakaolin, montmorillonite, attapulgite, expanded shale, carboxy methyl cellulose or perlite.

12. The admixture formulation as claimed in claim 1, wherein the superabsorbent polymer is selected from the group of the superabsorbent polymer may be Polyacrylamide copolymer and other bio-based super absorbent polymers, ethylene-maleic anhydride copolymer or polyvinyl alcohol copolymer.

13. A method of preparation of an admixture for cement plaster, the method comprising the steps of:

(i) mixing liquid component tertiary amine and alkali metal sulfate;

(ii) mixing of all other components along with the above said components;

(iii) blending the mixtures of steps (i) and (ii) in the blender for a period of 200-400 seconds; and

(iv) isolating the admixture.

14. The method as claimed in claim 13, wherein the alkali metal carbonate is calcium carbonate having a particle size of 2-20 microns.

15. The method as claimed in claim 13, wherein the alkali metal sulfate is sodium sulfate.

16. The method as claimed in claim 13, wherein the thickening agent is hydroxyl methylethyl cellulose or bentonite.

17. The method as claimed in claim 13, wherein the superabsorbent polymer is sodium poly acrylate.

18. The method as claimed in claim 13, wherein the tertiary amine is tri-ethanol amine or tri-isopropanol amine.

19. The method as claimed in claim 13, wherein the air entraining agent is sodium lauryl sulfate.

20. The method as claimed in claim 13, wherein the admixture is blended in a high precision blender.

21. The method as claimed in claim 13, wherein the admixture is mixed in a ratio of 0.1 to 3.0 percentage with cement.