Carbonated aerated concrete and preparation method thereof
By using raw materials such as steel slag and alkali activators and a simple preparation method, tiny bubbles are generated and industrial waste gas is used for curing, which solves the strength and environmental protection problems of carbonized aerated concrete, realizes the preparation of lightweight, high-strength and thermal-insulating carbonized aerated concrete, and reduces production costs and carbon dioxide emissions.
Patent Information
- Application Number
- CN202510110466.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-23
- Publication Date
- 2025-09-30
- Estimated Expiration
- 2045-01-23
AI Technical Summary
While existing carbonized aerated concrete improves strength and reduces production costs, it also has the problem of increased carbon dioxide emissions. In addition, the preparation process is complex, making it difficult to achieve both light weight and high strength, thermal insulation performance, and shrinkage performance.
The method uses steel slag, alkali activator, water reducer, sodium α-olefin sulfonate and aluminum sulfate solution as the main raw materials. Micro bubbles are formed by stirring and hydration products such as calcium aluminate and ettringite are generated during the carbonization curing process. Carbon dioxide in industrial waste gas is used for curing. The preparation process is simple and suitable for promotion and application.
Under the premise of energy conservation and emission reduction, the carbonized aerated concrete with light weight, high strength and good thermal insulation performance was prepared, which reduced the production cost, processed industrial waste and provided a new idea for high-performance aerated concrete.
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Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of building materials, and particularly relates to carbonized aerated concrete and a preparation method thereof. Background Art
[0002] Aerated concrete can generally be divided into autoclaved aerated concrete and non-autoclaved aerated concrete based on their curing methods. Their strength comes from hydration products such as calcium silicate hydrate, tobermorite, and ettringite, which are formed by the reaction of calcareous and siliceous materials. Although carbonated aerated concrete is a type of non-autoclaved aerated concrete, its strength primarily comes from calcium carbonate and silica gel, which are formed by the reaction of carbonizable materials with carbon dioxide. Because hydration products contain a large number of gel pores, their apparent density is significantly lower than that of carbonization reaction products such as calcium carbonate and silica gel. Therefore, when equal masses of reaction products are generated, the volume of hydration products is significantly higher than that of carbonization products, resulting in more complete contact between the hydration products and a better development of strength.
[0003] To improve the strength of carbonized aerated concrete, the current main research direction is to increase the amount of carbonizable materials in the mix design and impose strict requirements on the mineral composition to ensure that sufficient carbonized products are generated during the curing process. At the same time, a certain amount of hydraulic materials is added to ensure the normal hardening and forming of the body. For example, patent CN113956070A discloses a cement kiln exhaust carbonized autoclaved aerated concrete wall material product. The raw materials used include 5% to 10% silicate cement, 5% to 10% lime, and 30% to 50% synthetic carbonized active cement. This solution requires the introduction of higher amounts of cement and lime, combined with a high content of carbonized active cement, which not only increases production costs but also significantly increases carbon dioxide emissions during the raw material production process, which is not conducive to energy conservation and emission reduction. Summary of the Invention
[0004] The main purpose of the present invention is to address the problems and shortcomings of the existing technology and provide a carbonized aerated concrete that has good light weight, high strength, thermal insulation performance and shrinkage performance while saving energy and reducing emissions.
[0005] Another object of the present invention is to provide a method for preparing carbonized aerated concrete, which involves a simple curing method, is easy to operate, has a short preparation cycle, and is suitable for promotion and application.
[0006] To achieve the above object, the technical solution adopted by the present invention is:
[0007] The invention discloses carbonized aerated concrete. The raw materials and their weight proportions include: 90-95 parts of steel slag, 5-10 parts of alkali activator, 25-30 parts of water, 0.05-0.1 parts of water reducer, 0.1-0.2 parts of sodium α-olefin sulfonate and 3-5 parts of aluminum sulfate solution.
[0008] In the above scheme, the main chemical components and their mass percentages of the steel slag include: C2S 40-60%, C3S5-15%, Ca(OH)2 0-1%, Ca2Fe2O5 0-20%, CaCO3 0-10%, SiO2 0-10%; the specific surface area is 350-650m 2 / kg.
[0009] In the above solution, the alkali activator is preferably water glass, with a modulus of 2.0 to 2.5 and a concentration of 20 to 30 wt%.
[0010] In the above solution, the water reducer is a polycarboxylic acid high-efficiency water reducer with a water reduction rate of 35-45%.
[0011] In the above solution, the effective component of the sodium α-olefin sulfonate is not less than 95 wt%.
[0012] In the above scheme, the concentration of the aluminum sulfate solution is 20-25wt%.
[0013] The above-mentioned method for preparing carbonized aerated concrete comprises the following steps:
[0014] 1) Stir the steel slag, water reducer, alkali activator and water measured according to the ratio to obtain a slurry;
[0015] 2) stirring the clean slurry and sodium α-olefin sulfonate measured according to the ratio, and continuously introducing compressed air while stirring, to obtain a foam slurry after the stirring is completed;
[0016] 3) Under stirring conditions, evenly add the aluminum sulfate solution weighed according to the ratio into the foam slurry, and continue stirring to obtain a finished slurry;
[0017] 4) The obtained finished slurry is poured, allowed to stand for gasification and hardening, and demoulded to obtain a green body, which is then carbonized and cured using carbon-containing gas to obtain a finished carbonized aerated concrete product.
[0018] Preferably, the stirring step in step 1) comprises: first stirring slowly at a speed of 60 to 120 r / min for 2 to 4 minutes, and then stirring rapidly at a speed of 900 to 1200 r / min for 2 to 4 minutes.
[0019] In the above scheme, the stirring treatment in step 2) adopts a rotation speed of 200 to 500 r / min and a time of 5 to 10 minutes.
[0020] In the above scheme, in step 2), the rate of introduction of compressed air per cubic meter of slurry (neat slurry) is 2 to 5 L / s.
[0021] In the above solution, the pressure of the compressed air is 0.2-0.3 MPa.
[0022] In the above scheme, the stirring rate used in step 3) is 90-150 r / min.
[0023] Furthermore, in step 3), the addition time of the aluminum sulfate solution is 45 to 60 seconds; and the stirring time after the addition is 90 to 120 seconds.
[0024] In the above scheme, the temperature used in the static gas hardening step is 45-55° C., the relative humidity is not less than 80%, and the static time is 3-4 hours.
[0025] In the above scheme, the carbonization curing step includes: first vacuuming to a vacuum degree of -0.04 to -0.06 MPa, then filling the kettle with carbon-containing gas until the pressure in the kettle is 0.3 to 0.5 MPa, and curing for 5 to 8 hours to obtain a carbonized aerated concrete product.
[0026] Furthermore, the carbon-containing gas has a temperature of 50-100° C., a carbon dioxide concentration of 10-100 vol%, and a relative humidity of 20-60%.
[0027] Furthermore, the carbon-containing gas includes but is not limited to cement kiln tail gas, metal smelter tail gas, etc., preferably with a temperature of 70-90° C., a carbon dioxide concentration of 20-50%, and a relative humidity of 30-40%.
[0028] The carbonized aerated concrete prepared according to the above scheme has a compressive strength of 3.5-4.5 MPa and a bulk density of 600-650 kg / m 3 , drying shrinkage is 0.21~0.26mm / m, and thermal conductivity is 0.11~0.13W / (m·K).
[0029] The performance optimization mechanism of the carbonized aerated concrete of the present invention includes:
[0030] 1) The present invention first stirs steel slag, a water reducer, an alkali activator and water to obtain a pure slurry, then adds sodium α-olefin sulfonate for stirring, and introduces compressed air during the stirring process; the introduction of surface sodium α-olefin sulfonate can reduce the surface tension of water, and the introduction of compressed air into the pure slurry in combination with stirring conditions can form a large number of tiny bubbles; in the obtained mixed system, the hydrophobic group of the surfactant is directionally adsorbed toward the air side, and the hydrophilic group is directionally adsorbed toward the water side, which is beneficial to increasing the stability of the bubbles and maintaining good bubble stabilization performance in the mixed system that gradually releases a large amount of calcium ions; the stable existence of a large number of tiny bubbles can effectively reduce the sample's bulk density and thermal conductivity, and reduce the stress concentration phenomenon at the pore wall when the obtained sample is subjected to stress, which is beneficial to improving performance.
[0031] 2) The calcium ions dissolved in the liquid phase of the steel slag react with aluminum sulfate to form hydration products such as calcium aluminate and ettringite, causing the slurry to coagulate rapidly. This avoids problems such as mold collapse and sinking caused by excessive coagulation time, and solves the problem that the slurry is difficult to form in the absence of hydraulic materials (such as cement). In addition, the reaction product ettringite has a relatively obvious expansion effect, which can significantly reduce the drying shrinkage value of carbonized aerated concrete.
[0032] 3) Sodium α-olefin sulfonate forms lyotropic liquid crystals when dissolved in water, with nano-sized hydrophilic regions. Because the hydrophilic groups of the surfactant strongly adsorb calcium ions in the liquid phase, the carbonization curing process effectively reduces the size of the carbonized product, increases the specific surface area of the carbonized product, and allows for more complete contact, which helps improve carbonization strength.
[0033] 4) Steel slag powder has a large specific surface area and contains components with strong adsorption capacity, such as iron oxide and calcium oxide, on its surface. Water glass forms a negatively charged gel in the liquid phase and adsorbs on the surface of the steel slag, which helps reduce the adsorption of sodium α-olefin sulfonate by the steel slag and ensures the air entrainment effect during the molding process. In addition, aluminum ions generate amphoteric hydroxide Al(OH)3 under alkaline conditions, which generates negatively charged calcium carbonate crystals during the carbonization process. Al(OH)3 adsorbs on the surface of the calcium carbonate crystals. Under the action of the charge, Al(OH)3 adheres the negatively charged calcium carbonate crystals in a certain direction, ultimately forming chain-like and needle-like calcium carbonate, which is beneficial to the compressive strength and splitting tensile strength of carbonized aerated concrete.
[0034] Compared with the prior art, the present invention has the following beneficial effects:
[0035] 1) The present invention uses industrial waste slag as the main raw material to prepare carbonized aerated concrete, with the steel slag usage reaching more than 90%, and no cement needs to be introduced, which has significant cost advantages and can also process a large amount of industrial waste.
[0036] 2) The present invention can effectively utilize carbon dioxide and heat in industrial waste gas during the curing process, which has significant economic and environmental benefits.
[0037] 3) The carbonized aerated concrete obtained by the present invention has good light weight, high strength, thermal insulation performance and shrinkage performance, which can provide a new idea for the preparation of high-performance aerated concrete. DETAILED DESCRIPTION
[0038] The present invention will be further described in detail below with reference to the embodiments for a clearer understanding of the present invention, but they do not limit the present invention.
[0039] In the following examples and comparative examples, the steel slag used has the following main chemical compositions: C2S 56%, C3S 6%, Ca(OH)21%, Ca2Fe2O5 18%, CaCO3 8%, SiO2 9%; specific surface area 460m 2 / kg.
[0040] The alkali activator used is water glass, which has a modulus of 2.0 and a concentration of 25 wt%.
[0041] The water reducer used is polycarboxylic acid water reducer, and its water reduction rate is 42%.
[0042] The sodium α-olefin sulfonate used was provided by Zhonghe Chemical (Shandong) Co., Ltd., and the active ingredient content was 96 wt%.
[0043] The solid content (concentration) of the aluminum sulfate solution used is 21 wt %, and the effective component content in the solid content is 96 wt %.
[0044] Example 1
[0045] A carbonized aerated concrete, the preparation method of which comprises the following steps:
[0046] 1) Take 92 parts of steel slag, 8 parts of water glass, 0.1 parts of water reducer, and 25 parts of water, stir slowly at 90 r / min for 4 minutes, and then stir quickly at 900 r / min for 2 minutes to obtain a slurry;
[0047] 2) The clean slurry and 0.1 part of sodium α-olefin sulfonate were stirred at a speed of 250 r / min for 5 minutes, and 0.25 MPa compressed air was introduced at a rate of 3 L / s per cubic meter of slurry while stirring, and a foam slurry was obtained after the stirring was completed;
[0048] 3) Under stirring conditions of 120 r / min, 4 parts of aluminum sulfate solution were evenly added to the foam slurry within 60 seconds, and stirring was continued for 120 seconds to obtain the finished slurry;
[0049] 4) Pour the obtained finished slurry into a mold frame and allow it to harden in a static chamber at a temperature of 50°C and a relative humidity of 85%. After a static time of 3 hours, the slurry is hardened, demolded, and cut into a green body;
[0050] 5) subjecting the obtained green body to carbonization curing, specifically comprising the following steps: first, evacuating the green body to a vacuum degree of -0.05 MPa, then charging the green body with carbon-containing gas until the pressure in the green body reaches 0.4 MPa, and curing the green body for 8 hours to obtain a carbonized aerated concrete product; wherein the gas used for carbonization curing is cement kiln exhaust gas with a temperature of 75° C., a carbon dioxide concentration of 25 vol%, and a relative humidity of 38%.
[0051] Example 2
[0052] A carbonized aerated concrete, the preparation method of which is substantially the same as that of Example 1, except that: in step 1), 92 parts of steel slag, 8 parts of water glass, 0.05 parts of a water reducer, and 30 parts of water are taken, and slowly stirred at a speed of 90 r / min for 4 minutes, and then rapidly stirred at a speed of 900 r / min for 2 minutes to obtain a slurry.
[0053] Example 3
[0054] A carbonized aerated concrete and a preparation method thereof, wherein the preparation method is substantially the same as that in Example 1, except that: in step 2), the neat slurry and 0.1 part of sodium α-olefin sulfonate are stirred at a speed of 500 r / min for 10 min, and while stirring, 0.25 MPa compressed air is introduced at a rate of 5 L / s per cubic meter of slurry to obtain a foamed slurry after the stirring is completed.
[0055] Comparative Example 1
[0056] A carbonized aerated concrete and a preparation method thereof, wherein the preparation method is substantially the same as that in Example 1, except that: under stirring conditions of 120 r / min, 4 parts of aluminum chloride solution (21 wt%) are evenly added to the foam slurry within 60 s, and stirring is continued for 120 s to obtain the finished slurry.
[0057] Comparative Example 2
[0058] A carbonized aerated concrete and a preparation method thereof, wherein the preparation method is substantially the same as that in Example 1, except that: in step 2), the neat slurry and 0.1 part of sodium α-olefin sulfonate are stirred at a speed of 250 r / min for 5 min, and while stirring, 0.15 MPa compressed air is introduced at a rate of 3 L / s per cubic meter of slurry to obtain a foamed slurry after the stirring is completed.
[0059] Comparative Example 3
[0060] A carbonized aerated concrete and a preparation method thereof. The preparation method is substantially the same as that of Example 1, except that a fatty acid methyl ester sodium sulfate surfactant is used instead of the sodium α-olefin sulfonate of the present invention.
[0061] The carbonized aerated concrete obtained in Examples 1 to 3 and Comparative Examples 1 to 3 was subjected to performance tests according to the standard GB / T 11969-2008. The results are shown in Table 1.
[0062] Table 1 Carbonated aerated concrete performance test results
[0063]
[0064] The present invention is not limited to the above-described embodiments. Persons skilled in the art may make various improvements and modifications without departing from the principles of the present invention, and such improvements and modifications are deemed to be within the scope of protection of the present invention. Any matters not described in detail in this specification constitute prior art known to those skilled in the art.
Claims
1. A carbonized aerated concrete, characterized in that: The raw materials and their weight proportions include: 90-95 parts of steel slag, 5-10 parts of alkali activator, 25-30 parts of water, 0.05-0.1 parts of water reducer, 0.1-0.2 parts of sodium α-olefin sulfonate, and 3-5 parts of aluminum sulfate solution.
2. The carbonized aerated concrete according to claim 1, characterized in that The main chemical components and their mass percentages in the steel slag include: C2S 40-60%, C3S 5-15%, Ca(OH)2 0-1%, Ca2Fe2O5 0-20%, CaCO3 0-10%, SiO2 0-10%; specific surface area 350-650m 2 / kg.
3. The carbonized aerated concrete according to claim 1, characterized in that The alkali activator is water glass with a modulus of 2.0 to 2.5 and a concentration of 20 to 30 wt%.
4. The carbonized aerated concrete according to claim 1, characterized in that The water reducing agent is a polycarboxylic acid high-efficiency water reducing agent with a water reducing rate of 35-45%.
5. The carbonized aerated concrete according to claim 1, characterized in that The effective component of the sodium α-olefin sulfonate is not less than 95 wt %.
6. The carbonized aerated concrete according to claim 1, characterized in that The concentration of the aluminum sulfate solution is 20-25 wt%.
7. The method for preparing carbonized aerated concrete according to any one of claims 1 to 6, characterized in that: The steps include: 1) Stir the steel slag, water reducer, alkali activator and water measured according to the ratio to obtain a slurry; 2) stirring the clean slurry and sodium α-olefin sulfonate measured according to the ratio, and continuously introducing compressed air while stirring, to obtain a foam slurry after the stirring is completed; 3) Under stirring conditions, evenly add the aluminum sulfate solution weighed according to the ratio into the foam slurry, and continue stirring to obtain a finished slurry; 4) The obtained finished slurry is poured, allowed to stand for gasification and hardening, and demoulded to obtain a green body, which is then carbonized and cured using carbon-containing gas to obtain a finished carbonized aerated concrete product.
8. The preparation method according to claim 7, characterized in that In step 2), the rate of introduction of compressed air per cubic meter of slurry is 2 to 5 L / s; the pressure of the compressed air is 0.2 to 0.3 MPa.
9. The preparation method according to claim 7, characterized in that The carbonization curing step includes: first vacuuming to a vacuum degree of -0.04 to -0.06 MPa, then filling the kettle with carbon-containing gas until the pressure in the kettle reaches 0.3 to 0.5 MPa, and curing for 5 to 8 hours to obtain a carbonized aerated concrete product.
10. The preparation method according to claim 7, characterized in that The temperature of the carbon-containing gas is 50-100° C., the concentration of carbon dioxide is 10-100 vol%, and the relative humidity is 20-60%.