Composite auxiliary cementitious material, method for preparing same and use thereof

Abstract

The application discloses a kind of composite auxiliary cementitious materials and preparation method and application thereof, and the composite auxiliary cementitious material mainly includes microorganism synergic carbon fixation waste residue powder and aluminum-containing auxiliary cementitious material.The preparation step includes testing the content of alumina and calcium carbonate in microorganism synergic carbon fixation waste residue powder and aluminum-containing auxiliary cementitious material, so that when microorganism synergic carbon fixation waste residue powder and one or more aluminum-containing auxiliary cementitious materials are compounded, the mass ratio of alumina and calcium carbonate is 0.5-3.0.The overall chemical matching of the prepared composite auxiliary cementitious material is stronger, and the hydration activity is higher when used in cement concrete, which helps to reduce the clinker coefficient, reduce carbon emissions, and the microorganism synergic carbon fixation waste residue powder itself is a negative carbon material.

Description

Technical Field

[0001] This invention relates to a composite auxiliary cementitious material, and more particularly to its preparation method and application, belonging to the field of building materials. Background Technology

[0002] Applying industrial solid waste safely and efficiently to cement concrete is an important means of solving the current predicament of the cement industry.

[0003] Patent CN115159935A discloses a high-carbon-fixing and high-quality carbon-fixing auxiliary cementitious material, which comprises industrial waste residue modified by microbial carbon fixation and microbial components. The industrial waste residue modified by microbial carbon fixation is modified waste residue containing biogenic carbonate minerals or an amorphous gel phase. The microbial components are spores formed by microbial inoculum added to the industrial waste residue before the carbon fixation reaction and subsequently transformed. The biogenic carbonate component in the industrial waste residue modified by microbial carbon fixation accounts for 15% to 40%. However, this carbon-fixing auxiliary cementitious material has the problem of insufficient activity, which prevents it from further improving the overall performance of cement concrete and reducing the clinker coefficient. Summary of the Invention

[0004] Objectives of the invention: The objective of this invention is to provide a composite auxiliary cementitious material; another objective of this invention is to provide a method for preparing the composite auxiliary cementitious material; yet another objective of this invention is to provide an application of the composite auxiliary cementitious material.

[0005] Technical solution: The present invention provides a composite auxiliary cementitious material, which is composed of a carbon-fixing auxiliary cementitious material and other auxiliary cementitious materials. The carbon-fixing auxiliary cementitious material is prepared by microorganisms co-fixing industrial waste residue, and the carbon fixation content is 8.0% to 20.0%. The carbon-fixing auxiliary cementitious material contains calcium carbonate, and the other auxiliary cementitious materials contain alumina.

[0006] Furthermore, the mass ratio of alumina to calcium carbonate in the composite auxiliary cementitious material is calculated as the proportion of the carbon-fixing auxiliary cementitious material and other auxiliary cementitious materials, wherein the mass ratio of alumina to calcium carbonate is controlled to be 0.5 to 3.0.

[0007] Furthermore, the microorganisms required for the preparation of the carbon-fixing auxiliary gelling material are microorganisms capable of producing carbonic anhydrase.

[0008] Preferably, the microorganism is selected from one or more of the following microorganisms: Bacillus pasteurellii, Bacillus pumilus, Bacillus mucilaginosus, Bacillus alkalophilus, lactic acid bacteria, Lactobacillus acidophilus, and yeast.

[0009] Furthermore, the industrial waste residue required for the preparation of the carbon-fixing auxiliary cementitious material is alkaline waste residue.

[0010] Preferably, the industrial waste residue is selected from one or more of the following waste residues: slag, copper slag, steel slag, lithium slag, nickel slag, red mud, calcium carbide slag, and coal gangue.

[0011] On the other hand, the present invention provides a method for preparing a composite auxiliary cementitious material, comprising the following steps:

[0012] (1) Test the content of alumina and calcium carbonate in carbon-fixing auxiliary cementitious materials and other auxiliary cementitious materials;

[0013] (2) Control the mass ratio of alumina and calcium carbonate to 0.5 to 3.0, and calculate the usage ratio of carbon-fixing auxiliary cementitious materials and other auxiliary cementitious materials;

[0014] (3) Mix the carbon-fixing auxiliary cementitious material and one or more other auxiliary cementitious materials in the proportion of step (2), and the composite auxiliary cementitious material is obtained after mixing.

[0015] Furthermore, in step (1), the carbon fixation auxiliary cementitious material is prepared by microorganisms in synergistic carbon fixation of industrial waste residue, and the carbon fixation content is 8.0% to 20.0%.

[0016] Furthermore, in step (3), the mixing method is to place the mixture in a mixer and mix for 3 to 5 minutes.

[0017] On the other hand, the present invention provides an application of the above-mentioned composite auxiliary cementitious material in the preparation of cement concrete.

[0018] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: (1) It utilizes waste residue powder and mineralizing microorganisms to directly fix industrial CO2, thereby obtaining carbon-fixed waste residue powder with higher activity and higher environmental benefits; (2) Based on the chemical composition characteristics of the carbon-fixed waste residue powder, the chemical composition is regulated to improve its reactivity in cement-based materials. Compared with the use of single carbon-fixed waste residue powder, the hydration activity is higher, which can further reduce the clinker coefficient and achieve higher carbon emission reduction benefits. Attached Figure Description

[0019] Figure 1 The figures show the reaction amounts of calcium carbonate at different ages. In the figures, B-Ca15Q15: 15% bio-based calcium carbonate, 70% cement, and 15% quartz powder; B-Ca15F15: 15% bio-based calcium carbonate, 70% cement, and 15% fly ash; C-Ca15Q15: 15% chemical calcium carbonate, 70% cement, and 15% quartz powder; C-Ca15F15: 15% chemical calcium carbonate, 70% cement, and 15% fly ash. Detailed Implementation

[0020] The technical solution of the present invention will be further described below with reference to the accompanying drawings.

[0021] This invention provides a composite auxiliary cementitious material, which is composed of a carbon fixation auxiliary cementitious material and other auxiliary cementitious materials. The carbon fixation auxiliary cementitious material is prepared by microorganisms co-fixing industrial waste residue with carbon, and the carbon fixation content is 8.0% to 20.0%. The carbon fixation auxiliary cementitious material contains calcium carbonate, and the other auxiliary cementitious materials contain alumina.

[0022] The preparation method of the carbon-fixing assisted cementitious material refers to the preparation method described in Example 2 of patent CN115159935A. The preparation method of the carbon-fixing assisted cementitious material involved in this example is as follows:

[0023] (1) Steel slag powder and microbial additives are premixed at a mass ratio of 6%, water is added and stirred evenly, the liquid-solid ratio is kept at 0.15, and the mixture is placed in an environment at 30℃ for 24 hours to regulate the physicochemical environment of industrial waste slag powder using microorganisms; (2) The mixture is then placed in an environment with a concentration of 20% CO2, relative humidity of 80% and temperature of 30℃ for stirring and curing, using microorganisms to improve the carbon fixation rate and form mineral products. After the carbon fixation reaction is 30 minutes, it is taken out to obtain steel slag with a carbon fixation content of 8% containing microbial components and biocarbonate components. (3) The carbon-fixed steel slag is dried at 50℃ and ground through a 100μm square hole sieve to obtain carbon-fixed steel slag powder.

[0024] In this step (2), the carbon fixation reaction time was changed to 60 min, and a carbon-fixed steel slag powder with a carbon fixation content of 10% containing microbial components and biocarbonate components was finally obtained.

[0025] Example 1:

[0026] This embodiment provides a method for preparing a composite auxiliary cementitious material, including the following steps:

[0027] (1) Carbon-fixed steel slag powder was selected as the auxiliary cementitious material for carbon fixation, with a carbon fixation content of 8.0%; fly ash was selected as the other auxiliary cementitious material; the contents of alumina and calcium carbonate in carbon-fixed steel slag powder and fly ash were tested respectively.

[0028] (2) Control the mass ratio of alumina and calcium carbonate to 1.35, and calculate the usage ratio of carbon-fixing auxiliary cementitious materials and other auxiliary cementitious materials;

[0029] (3) The carbon steel slag powder and fly ash were calculated to be compounded in a mass ratio of 1:1 and then placed in a mixer for 3 min to 5 min.

[0030] (4) Test the stability and activity index of the composite auxiliary cementitious material.

[0031] Example 2:

[0032] The difference from Example 1 is that: the carbon-fixed steel slag powder and fly ash are compounded in a mass ratio of 1:1, wherein the carbon fixation content of the carbon-fixed steel slag powder is 10.0%, and the ratio of alumina to calcium carbonate is 1.60. After being mixed evenly, the stability and activity index are tested.

[0033] Example 3:

[0034] The difference from Example 1 is that: the carbon-fixed steel slag powder and fly ash are compounded in a mass ratio of 2:1, wherein the carbon fixation content of the carbon-fixed steel slag powder is 10.0%, and the ratio of alumina to calcium carbonate is 0.78. After being mixed evenly, the stability and activity index are tested.

[0035] Example 4:

[0036] The difference from Example 1 is that: the carbon-fixed steel slag powder and fly ash are compounded in a mass ratio of 1:2, wherein the carbon fixation content of the carbon-fixed steel slag powder is 10.0%, and the ratio of alumina to calcium carbonate is 2.89. After being mixed evenly, the stability and activity index are tested.

[0037] Example 5:

[0038] The difference from Example 1 is that blast furnace slag powder was selected as another auxiliary cementing material, and carbon-fixed steel slag powder and blast furnace slag powder were compounded in a mass ratio of 1:1, wherein the carbon fixation content of the carbon-fixed steel slag powder was 10.0%, and the ratio of alumina to calcium carbonate was 0.90. After being mixed evenly, the stability and activity index were tested.

[0039] Example 6:

[0040] The difference from Example 1 is that blast furnace slag powder was selected as another auxiliary cementing material, and carbon-fixed steel slag powder and blast furnace slag powder were compounded at a mass ratio of 1:2, wherein the carbon fixation content of the carbon-fixed steel slag powder was 10.0%, and the ratio of alumina to calcium carbonate was 1.57. After being mixed evenly, the stability and activity index were tested.

[0041] Comparative Example 1:

[0042] This comparative example provides an auxiliary cementitious material that directly utilizes single steel slag powder without carbon fixation, and tests its stability and activity index.

[0043] Comparative Example 2:

[0044] This comparative example provides an auxiliary cementing material that directly utilizes a single carbon-fixed steel slag powder, the same carbon-fixed steel slag powder used in Example 1, with a carbon fixation content of 8.0%, and tests its stability and activity index.

[0045] Comparative Example 3:

[0046] This comparative example provides an auxiliary cementing material that directly utilizes a single carbon-fixed steel slag powder, the same carbon-fixed steel slag powder used in Example 2, with a carbon fixation content of 10.0%, and tests its stability and activity index.

[0047] Comparative Example 4:

[0048] This comparative example provides an auxiliary cementing material that directly utilizes single carbon-fixing steel slag powder with a carbon fixation content of 10.0%. Its stability and activity index were tested. Compared to Comparative Example 3, the carbon-fixing steel slag powder in this comparative example is obtained by direct carbon fixation of steel slag without the addition of microorganisms. The preparation steps of the carbon-fixing steel slag powder are the same as in Comparative Example 3, the difference being the absence of added microorganisms and a carbon fixation reaction time of 48 hours.

[0049] Comparative Example 5:

[0050] This comparative example provides an auxiliary cementing material, which differs from Example 1 in that: the carbon-fixing auxiliary cementing material used is the steel slag powder in Comparative Example 1, i.e., uncarbonized steel slag powder; the uncarbonized steel slag powder and fly ash in Comparative Example 1 are compounded at a mass ratio of 1:1, and after being mixed evenly, the stability and activity index are tested.

[0051] Comparative Example 6:

[0052] This comparative example provides an auxiliary cementing material, which differs from Example 1 in that: the carbon-fixing auxiliary cementing material used is the carbon-fixing steel slag powder in Comparative Example 4, that is, carbon-fixing steel slag powder without added microorganisms; the carbon-fixing steel slag powder and fly ash in Comparative Example 4 are compounded at a mass ratio of 1:1, wherein the carbon fixation content of the carbon-fixing steel slag powder is 10.0%, and the ratio of alumina to calcium carbonate is 1.35. After being mixed evenly, the stability and activity index are tested.

[0053] The fly ash and blast furnace slag powder mentioned in the above cases both met the stability requirements, with activity indices of 80% and 90% respectively after 28 days.

[0054] The activity index test method shall be performed in accordance with the provisions of GB / T 20491 "Steel slag powder for use in cement and concrete".

[0055] The stability test method adopted is the Le Chatelier method, and the test method is carried out in accordance with the provisions of the current national standard GB / T 1346 "Standard Consistency Water Requirement, Setting Time and Soundness Test Method of Cement".

[0056] Serial Number Carbon sequestration / % Dosage / % 28d activity index / % Stability Comparative Example 1 0 30 75.52 Unqualified Comparative Example 2 8 30 82.26 qualified Comparative Example 3 10 30 84.56 qualified Comparative Example 4 10 30 80.12 qualified Comparative Example 5 0 30 77.59 qualified Comparative Example 6 10 30 83.67 qualified Example 1 8 30 85.11 qualified Example 2 10 30 89.72 qualified Example 3 10 30 86.35 qualified Example 4 10 30 87.21 qualified Example 5 10 30 94.16 qualified Example 6 10 30 94.68 qualified

[0057] The above cases demonstrate that, compared to steel slag powder, steel slag powder exhibits higher activity after carbon fixation, with the highest activity observed during synergistic carbon fixation by microorganisms. Under the same carbon fixation conditions, adjusting the chemical composition of the composite auxiliary cementitious material can improve overall chemical compatibility and better leverage the reactivity of the composite auxiliary cementitious material in cement-based materials. Macroscopically, this manifests as higher hydration activity, exceeding that of any single component.

[0058] The mechanism of chemical compatibility of composite auxiliary cementitious materials is as follows: After carbon fixation by steel slag powder, alkaline calcium-containing minerals react with CO2 to form calcium carbonate minerals. Calcium carbonate can participate in cement hydration, but the reaction rate is relatively slow. The incorporation of aluminum-containing auxiliary cementitious materials accelerates the participation of calcium carbonate in cement hydration. Compared with chemical calcium carbonate formed by ordinary carbon fixation methods, the intervention of microorganisms not only improves carbon sequestration efficiency but also produces bioreactive calcium carbonate. See details. Figure 1 Quartz powder is inert and does not participate in the reaction. The conversion efficiency of calcium carbonate is improved after adding fly ash, and the conversion rate of bio-calcium carbonate is even better. Therefore, carbon-fixed steel slag powder formed by microbial synergistic carbon fixation is preferred.

Claims

1. A composite auxiliary cementitious material, characterized in that, The composite auxiliary cementitious material is composed of a carbon-fixing auxiliary cementitious material and other auxiliary cementitious materials. The carbon-fixing auxiliary cementitious material is prepared by microorganisms co-fixing industrial waste residue with carbon, and the carbon fixation content is 8.0% to 20.0%. The carbon-fixing auxiliary cementitious material contains calcium carbonate. The other auxiliary cementitious materials contain alumina. The mass ratio of alumina to calcium carbonate in the composite auxiliary cementitious material is calculated as the ratio of the carbon-fixing auxiliary cementitious material to the other auxiliary cementitious materials, wherein the mass ratio of alumina to calcium carbonate is controlled to be 0.5 to 3.

0. The microorganisms required for the preparation of the carbon-fixing auxiliary cementitious material are microorganisms capable of producing carbonic anhydrase. The industrial waste residue required for the preparation of the carbon-fixing auxiliary cementitious material is alkaline waste residue.

2. The composite auxiliary cementitious material according to claim 1, characterized in that, The microorganisms are selected from one or more of the following: Bacillus pasteurellii, Bacillus pumilus, Bacillus mucilaginosus, Bacillus alkalophilus, lactic acid bacteria, Lactobacillus acidophilus, and yeast.

3. The composite auxiliary cementitious material according to claim 1, characterized in that, The industrial waste residue is selected from one or more of the following: slag, steel slag, copper slag, lithium slag, nickel slag, red mud, calcium carbide slag, and coal gangue.

4. A method for preparing the composite auxiliary cementitious material according to any one of claims 1-3, characterized in that, Includes the following steps: (1) Test the content of alumina and calcium carbonate in carbon-fixing auxiliary cementitious materials and other auxiliary cementitious materials; (2) Control the mass ratio of alumina and calcium carbonate to 0.5 ~ 3.0, and calculate the usage ratio of carbon-fixing auxiliary cementitious materials and other auxiliary cementitious materials; (3) Mix the carbon-fixing auxiliary cementitious material and one or more other auxiliary cementitious materials in the proportion of step (2), and the composite auxiliary cementitious material is obtained after mixing.

5. The method for preparing the composite auxiliary cementitious material according to claim 4, characterized in that, In step (1), the carbon fixation auxiliary cementitious material is prepared by microorganisms in synergistic carbon fixation of industrial waste residue, and the carbon fixation content is 8.0% to 20.0%.

6. The method for preparing the composite auxiliary cementitious material according to claim 4, characterized in that, In step (3), the mixing method is to place the mixture in a mixer and mix for 3 min to 5 min.

7. The application of a composite auxiliary cementitious material according to any one of claims 1-3 in the preparation of cement concrete.

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