Carbon-fixable cementing material as well as preparation method and application thereof

Abstract

The invention provides a cementing material capable of fixing carbon as well as a preparation method and application of the cementing material. The cementitious material capable of fixing carbon is composed of gamma-C2S powder, gypsum powder, water and a water reducing agent, and CO2 is adopted as curing gas. The invention relates to a novel cementing material, and aims to provide a material which can be carbonized at any time, can be poured and has a carbon sequestration function by utilizing the characteristic of rapid setting and hardening of gypsum. Through the specific raw material ratio and process steps, the material slurry has early strength before carbonization, and effective pouring and quick form removal in the construction process are facilitated. And after the mold is removed, the carbonization time can be flexibly selected, the storage time of the cementing material before CO2 curing is prolonged, and the convenience of the carbonization process and the simplicity of operation are remarkably improved. The cementitious material has carbon sequestration capability, and through optimization design and process, the production cost is reduced, the environmental burden is reduced, and the development of low-carbon environmental protection technology is promoted.

Description

Technical Field

[0001] The invention relates to a novel building material, in particular to a carbon-fixing cementitious material and a preparation method and application thereof. Background Art

[0002] In the field of building materials, γ-type dicalcium silicate (γ-C2S) is a material that does not have water hardness, but it can react quickly with CO2 at room temperature and pressure to generate calcium carbonate and high-density silica gel, thereby hardening the material. However, γ-C2S-based cementitious materials must be cured with CO2 immediately after molding to avoid powdering, volume changes and structural damage caused by long-term exposure, which puts forward high timeliness requirements for production processes and equipment. In practical applications, it not only increases the complexity and cost of the production line, but also limits the feasibility of its large-scale industrial application.

[0003] These technical bottlenecks need to be broken through urgently to further promote the popularization and application of γ-C2S-based cementitious materials. Summary of the invention

[0004] In view of this, the present invention aims to prepare a new type of building material which can be carbonized at any time, can be effectively cast, is easy to produce and has a strong carbon fixation function.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0006] The present invention provides a carbon-fixable cementitious material. The raw material formula of the carbon-fixable cementitious material comprises the following components in percentage by weight: a composite powder formed by 5%-95% of γ-C2S powder and 5%-95% of gypsum powder, wherein the sum of the percentages of the γ-C2S powder and the gypsum powder is 100%; and a water reducing agent accounting for 0-0.3% of the weight of the composite powder and water accounting for 10%-50% of the weight of the composite powder.

[0007] Furthermore, the main component of the gypsum powder is one or more of calcium sulfate dihydrate, calcium sulfate hemihydrate or anhydrous calcium sulfate.

[0008] Furthermore, the gypsum powder is specifically one or more of phosphogypsum, desulfurized gypsum, building gypsum or fluorinated gypsum.

[0009] The present invention also provides a preparation method of the above-mentioned carbon-fixable cementitious material, which comprises the following steps: 1) mixing: firstly mixing γ-C2S powder and gypsum powder, stirring until the mixture is uniform, to obtain a mixed powder; adding water and a water reducing agent to the mixed powder, stirring until the mixture is fully mixed, to obtain a mixed material; 2) molding: filling the mixed material to 1 / 3 of the total height of the mold, and then tamping 10-20 times from the edge to the center in the same direction, statically pressing and molding, and then continuing to repeat the operation of filling the mixed material and tamping until it overflows the mold and then smoothing, to obtain the carbon-fixable cementitious material.

[0010] Furthermore, the preparation method also includes: 3) curing the carbon-fixable cementitious material indoors for 0-24 hours, removing the mold after the curing is completed, and then curing with CO2 gas.

[0011] Furthermore, in step 1), when water is added to the mixed powder and stirred, the stirring speed is 200 r / min and the stirring time is 2-3 min.

[0012] Furthermore, in step 1), the water-cement ratio of the mixed material to water is 10%-50%.

[0013] Furthermore, in step 2), the mixed material is pressed into shape three times, the first pressing pressure is 12.5-37.5 MPa; the second pressing pressure is 37.5-62.5 MPa; the third pressing pressure is 62.5-87.5 MPa, and the pressing time for each pressing is 1-2 min.

[0014] Furthermore, in step 3), the curing conditions are: first curing indoors for 0-24 hours; then CO2 curing, the CO2 concentration is 5%-100%, the curing time is 5h-6d, the temperature is 20℃-60℃, and the relative humidity is 40%-60%.

[0015] The present invention also provides the use of the above-mentioned carbon-fixable cementitious material in the field of construction.

[0016] Compared with the prior art, the technical solution provided by the present invention has at least the following advantages:

[0017] The present invention provides a carbon-fixable cementitious material and a preparation method and application thereof. The method utilizes the differences in properties between materials and optimizes process parameters so that the γ-C2S slurry before carbonization can obtain early strength, thereby achieving rapid demoulding, significantly extending the storage time before later CO2 curing, and allowing the carbonization time to be flexibly selected according to actual needs. The carbon-fixable cementitious material obtained by the preparation method provided by the present invention overcomes the problem of time limitation in traditional technology, and has the characteristics of convenient production and flexible use. In addition, the method focuses on efficient utilization of resources and environmental friendliness, and further reduces the environmental burden in the production process by utilizing industrial solid waste to achieve resource processing of waste. The material can meet the urgent needs of the modern construction industry for energy conservation and emission reduction, and has a wide range of applicability, providing a green and efficient solution for the construction industry, which helps promote its application and development in construction and related fields. DETAILED DESCRIPTION

[0018] Based on the problems existing in the prior art of γ-C2S-based cementitious materials, the inventors also found that a large amount of industrial waste slag containing gypsum (such as phosphogypsum, desulfurized gypsum, fluorinated gypsum, etc.) is generated every year during the industrial production process. At present, the comprehensive utilization rate of these solid waste resources is low, and most of them are treated in a stockpiling manner, occupying land resources, and may cause environmental pollution and safety hazards, such as water pollution accidents caused by the collapse of phosphogypsum yards. In this context, the combination of gypsum solid waste and γ-C2S can not only make full use of the early setting characteristics of gypsum, provide early strength for γ-C2S-based materials, and facilitate rapid demoulding, but also effectively consume industrial solid waste and reduce land occupation and environmental pollution problems.

[0019] In view of this, the inventors combined gypsum solid waste with γ-C2S to provide a new type of building material that can be carbonized at any time, can be effectively cast, is easy to produce, and has a strong carbon fixation function. It will provide a new idea for solving the timeliness limitations of existing CO2 maintenance technology, and at the same time promote the industrial production and application of γ-C2S-based cementitious materials. It not only provides theoretical support for the research and application of carbonized building materials, but also proposes solutions to key issues in the field of low-carbon and environmentally friendly building materials, showing broad application prospects and economic benefits.

[0020] The present invention is described in detail below in conjunction with specific implementation modes.

[0021] Embodiment 1:

[0022] Dry the solid waste and grind it for later use. Weigh the raw materials according to the following proportions:

[0023] Gypsum powder and γ-C2S powder are taken in a weight ratio of 1:1, water is taken at 30% of the weight of the composite powder material, and a water reducing agent is taken at 0.01% of the weight of the composite powder material. The specific preparation steps are as follows.

[0024] (1) Gypsum powder and γ-C2S powder are mixed in a mixer at a weight ratio of 1:1, and stirred for 1 minute to mix them evenly to obtain a mixed powder. Water accounting for 30% of the weight of the composite powder material and a water reducing agent accounting for 0.01% of the weight of the composite powder material are added to the prepared mixed powder, and stirred evenly to mix them fully to obtain a mixed material.

[0025] (2) The mixed material is loaded to 1 / 3 of the total height of the triple mold, and a tamping rod is used to tamp 15 times in the same direction from the edge to the center to form static pressure, and then the mixed material is continued to be loaded, and such operations are repeated until it overflows the mold, and finally smoothed with a spatula. The mixed material is pressed and formed three times, the pressure of the first pressing is 25MPa, and the pressing time is 30s; the pressure of the second pressing is 50MPa, and the pressing time is 30s; the pressure of the third pressing is 75MPa, and the pressing time is 30s.

[0026] (3) The cementitious material obtained in step 2) is first cured indoors for 24 hours and then subjected to CO2 curing, wherein the CO2 concentration is 5%, the curing time is 6 days, the temperature is 28° C., and the relative humidity is 50%.

[0027] The carbon-fixable cementitious material obtained in this example was tested for mechanical properties according to GB / T50081-2002 "Standard for Test Methods for Mechanical Properties of Ordinary Concrete".

[0028] According to the test, the compressive strength of the carbon-fixable cementitious material of this embodiment is 24.5 MPa. Compared with the conventional technology, the carbon-fixable cementitious material reaches initial setting during indoor curing, which is convenient for demoulding.

[0029] Embodiment 2:

[0030] The materials used in this example are the same as those in Example 1. The raw materials are weighed according to the following proportions:

[0031] Gypsum powder and γ-C2S powder were taken at a weight ratio of 19:1, water was taken at 30% of the weight of the composite powder material, and a water reducing agent was taken at 0.01% of the weight of the composite powder material. Other operating parameters were the same as those in Example 1:

[0032] The carbon-fixable cementitious material obtained in this example was tested for mechanical properties according to GB / T50081-2002 "Standard for Test Methods for Mechanical Properties of Ordinary Concrete".

[0033] The test shows that the compressive strength of the carbon-fixable cementitious material of this embodiment is 29.58 MPa.

[0034] Embodiment 3:

[0035] The materials used in this example are the same as those in Example 1. The raw materials are weighed according to the following proportions:

[0036] Gypsum powder and γ-C2S powder were taken at a weight ratio of 1:19, water was taken at 30% of the weight of the composite powder material, and a water reducing agent was taken at 0.01% of the weight of the composite powder material. Other operating parameters were the same as those in Example 1.

[0037] The carbon-fixable cementitious material obtained in this example was tested for mechanical properties according to GB / T50081-2002 "Standard for Test Methods for Mechanical Properties of Ordinary Concrete".

[0038] The test shows that the compressive strength of the carbon-fixable cementitious material of this embodiment is 4.32 MPa.

[0039] Comparative Example 1:

[0040] Weigh the raw materials according to the following proportions:

[0041] Take gypsum powder and γ-C2S powder at a weight ratio of 0:10, take water at 30% of the weight of the composite powder material, and take a water reducing agent at 0.01% of the weight of the composite powder material. The specific preparation steps are as follows:

[0042] (1) According to the above ratio, add 30% of water and 0.01% of water reducing agent to the γ-C2S powder, stir evenly, and fill the obtained mixed raw material to 1 / 3 of the total height of the triple mold. Use a tamping rod to tamp 15 times from the edge to the center in the same direction, statically press and shape, and then continue to fill the mixed material. Repeat this operation until it overflows the mold, and finally smooth it with a spatula. The mixed material is pressed and molded three times. The pressure of the first pressing is 25MPa and the pressing time is 30s; the pressure of the second pressing is 50MPa and the pressing time is 30s; the pressure of the third pressing is 75MPa and the pressing time is 30s.

[0043] (2) The prepared cementitious material is first cured indoors for 24 hours and then subjected to CO2 curing, with a CO2 concentration of 5% and a curing time of 6 days at a temperature of 28°C and a relative humidity of 50%.

[0044] The mechanical properties of the carbon-fixable cementitious material obtained in this comparative example were tested according to GB / T50081-2002 "Standard for Test Methods for Mechanical Properties of Ordinary Concrete".

[0045] The test showed that after the triple mold was demolded, the test block did not harden, and the test block was deformed during the subsequent CO2 curing process.

[0046] In summary, the present invention provides a method for preparing a carbon-fixable cementitious material by combining gypsum solid waste with γ-C2S powder. The prepared cementitious material exhibits excellent compressive strength under CO2 curing conditions, verifying the practicality and reliability of the preparation method. The present invention realizes the resource utilization of solid waste, overcomes the timeliness limitation of existing CO2 curing technology, and has broad industrial application prospects and significant environmental benefits.

[0047] The above description is only a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail through the above embodiments, those skilled in the art can still make various improvements, equivalent substitutions or modifications to the technical solution without departing from the spirit and principles of the present invention. Any improvements, changes or substitutions made within the spirit and principles of the present invention should be deemed to fall within the scope of protection of the present invention. Although specific implementation methods have been described, these descriptions should not be construed as limiting the scope of protection of the present invention. Based on the technical solution of the present invention, all modifications or deformations made by those skilled in the art without the need for creative work still fall within the scope of protection of the present invention.

Claims

1. A carbon-fixable cementitious material, characterized in that: The raw material formula of the carbon-fixable cementitious material includes the following components in percentage by weight: a composite powder formed by 5%-95% of γ-C2S powder and 5%-95% of gypsum powder, wherein the sum of the percentages of the γ-C2S powder and the gypsum powder is 100%; and a water reducer accounting for 0-0.3% of the weight of the composite powder and water accounting for 10%-50% of the weight of the composite powder.

2. The carbon-fixable cementitious material according to claim 1, characterized in that: The main component of the gypsum powder is one or more of calcium sulfate dihydrate, calcium sulfate hemihydrate or anhydrous calcium sulfate.

3. The carbon-fixable cementitious material according to claim 2, characterized in that: The gypsum powder is specifically one or more of phosphogypsum, desulfurized gypsum, building gypsum or fluorinated gypsum.

4. The method for preparing the carbon-fixable cementitious material according to claims 1 to 3, characterized in that: The preparation method comprises the following steps: 1) Mixing: First, γ-C2S powder and gypsum powder are mixed and stirred until they are evenly mixed to obtain a mixed powder; water and a water reducing agent are added to the mixed powder and stirred until they are fully mixed to obtain a mixed material; 2) Molding: Fill the mixture to 1 / 3 of the total height of the mold, then tamp 10-20 times from the edge to the center in the same direction, statically press mold, and continue to repeat the operation of filling the mixture and tamping until it overflows the mold and then smoothes it to obtain the solidifiable carbon cementitious material.

5. The method for preparing a carbon-fixable cementitious material according to claim 4, characterized in that: The preparation method also includes: 3) Curing the carbon-fixable cementitious material indoors for 0-24 hours, removing the mold after the curing is completed, and then curing with CO2 gas.

6. The method for preparing a carbon-fixable cementitious material according to claim 4, characterized in that: In step 1), when water is added to the mixed powder and stirred, the stirring speed is 200 r / min and the stirring time is 2-3 min.

7. The method for preparing a carbon-fixable cementitious material according to claim 2, characterized in that: In step 1), the water-cement ratio of the mixed material to water is 10%-50%.

8. The method for preparing a carbon-fixable cementitious material according to claim 2, characterized in that: In step 2), the mixed material is pressed into shape three times, the first pressing pressure is 12.5-37.5 MPa; the second pressing pressure is 37.5-62.5 MPa; the third pressing pressure is 62.5-87.5 MPa, and the pressing time for each pressing is 1-2 min.

9. The method for preparing a carbon-fixable cementitious material according to claim 2, characterized in that: In step 3), the curing conditions are: first curing indoors for 0-24 hours; then CO2 curing, the CO2 concentration is 5%-100%, the curing time is 5h-6d, the temperature is 20℃-60℃, and the relative humidity is 40%-60%.

10. Use of the carbon-fixable cementitious material as claimed in claims 1 to 3 in the field of construction.