A preparation process of a concrete material with carbon reduction and micro-crack self-repairing functions
By introducing mesoporous silica powder loaded with magnesium hydroxide and calcium carbide slag powder into concrete materials to prepare modified materials, a self-healing agent is formed, which solves the problem of difficult treatment of microcracks in concrete, improves structural strength and durability, and reduces carbon emissions.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- CCCC SIGONG CONSTR TECH (JINAN) CO LTD
- Filing Date
- 2026-01-08
- Publication Date
- 2026-07-07
AI Technical Summary
Concrete materials are prone to developing microcracks during use, leading to reduced structural durability and steel corrosion. Traditional repair methods are difficult to effectively treat internal microcracks and are resource-intensive and costly.
Magnesium hydroxide was loaded onto mesoporous silica powder and calcined to form an active powder. This active powder was then mixed with powdered polycarboxylate superplasticizer and potassium dihydrogen phosphate powder to form a microcrack self-healing agent. Tetraethoxysilane was loaded onto the microcrack using a silane coupling agent and combined with carbide slag powder to prepare a modified material. Calcium carbonate was used to fill the micropores to improve the density of the concrete matrix.
It enables the self-healing ability of microcracks in concrete materials, improves structural strength and durability, reduces carbon emissions, and lowers repair costs and resource consumption.
Smart Images
Figure CN121698618B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of concrete material preparation technology, specifically to a concrete material preparation process that combines carbon reduction and microcrack self-healing functions. Background Technology
[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.
[0003] Concrete, as the most widely used building material globally, has long been plagued by cracking problems due to its inherent brittleness. On one hand, during the hardening process, cement hydration generates a large amount of heat, leading to temperature differences between the inside and outside of the concrete, thus inducing temperature shrinkage stress. Simultaneously, concrete loses water, causing drying shrinkage. When the resulting tensile stress exceeds the concrete's tensile strength, plastic shrinkage cracks or drying shrinkage cracks will form. On the other hand, during the service life of concrete structures, freeze-thaw cycles caused by drastic temperature changes can also generate internal stress in the concrete. This is because water that has seeped into the capillaries of the concrete expands in volume when it freezes, and the resulting pressure easily triggers the formation of microcracks.
[0004] It is evident that the formation of microcracks is an inherent weakness of concrete structures. It not only reduces the durability and load-bearing capacity of concrete structures but also provides channels for harmful substances such as moisture and chloride ions to penetrate, accelerating steel corrosion and concrete deterioration, shortening lifespan, and increasing maintenance costs. Traditional repair methods are mostly passive manual interventions, often struggling to detect and effectively treat internal or minute cracks. Furthermore, large-scale repair projects consume significant manpower and resources, affecting normal building use and exhibiting limitations such as high cost, complex processes, and difficulty in accessing internal microcracks. Self-healing technology, on the other hand, enables early, proactive, and continuous repair, preventing problems before they occur and significantly improving the safety and reliability of structures. This helps extend the service life of concrete structures and reduces resource consumption, construction waste, and carbon emissions resulting from large-scale repairs or demolition and reconstruction. Summary of the Invention
[0005] This invention provides a concrete material preparation process that combines carbon reduction and microcrack self-healing functions. It not only endows the concrete material with excellent microcrack self-healing capabilities but also reduces carbon emissions from cement clinker production by consuming carbon dioxide. Specifically, the technical solution of this invention is as follows.
[0006] A process for preparing a concrete material that combines carbon reduction and microcrack self-healing functions includes the following steps:
[0007] (1) Mesoporous silica powder was mixed with a solution containing magnesium ion source and stirred. Then, an alkaline solution was added and allowed to stand. After completion, the residual alkaline solution was washed away, and then calcined to obtain MgO@mesoporous silica active powder.
[0008] (2) The powdered polycarboxylate superplasticizer, potassium dihydrogen phosphate powder and the active powder are mixed and ground. Then the modified powder is added to anhydrous ethanol containing polyethylene glycol, stirred evenly and spray-dried to obtain the precursor powder.
[0009] (3) The precursor powder is mixed with anhydrous ethanol containing silane coupling agent and stirred. Then tetraethoxysilane is added and stirred evenly. Then spray-drying is performed to obtain microcrack self-healing agent.
[0010] (4) Using cement, coarse aggregate, fine aggregate, silica fume, modified carbide slag powder, and the microcrack self-healing agent as raw materials, mix them and add water to stir evenly to obtain the concrete material.
[0011] Further, in step (1), the ratio of the mesoporous silica powder to the solution containing the magnesium ion source is 1g:6~8.5mL. Optionally, the concentration of the magnesium ion source in the solution is 2~4mol / L.
[0012] Further, in step (1), the magnesium ion source includes at least one of magnesium chloride, magnesium sulfate, magnesium nitrate, etc.
[0013] Furthermore, in step (1), the stirring time is 20~30 min.
[0014] Further, in step (1), the molar ratio of hydroxide ions to magnesium ions in the alkaline solution is 2~2.1:1.
[0015] Further, in step (1), the alkaline solution includes at least one of sodium hydroxide, potassium hydroxide, and ammonia. Optionally, the standing time is 10-15 minutes.
[0016] Further, in step (1), the calcination treatment temperature is 520~580℃ and the time is 30~40min.
[0017] Further, in step (2), the ratio of the powdered polycarboxylate superplasticizer, potassium dihydrogen phosphate powder, and active powder is 0.12~0.16g: 1~1.45g: 20~25g.
[0018] Further, in step (2), the ratio of the modified powder to anhydrous ethanol containing dissolved polyethylene glycol is 1 g: 5~10 mL. Optionally, the mass fraction of polyethylene glycol in the anhydrous ethanol is 20~30%.
[0019] Furthermore, in step (2), the fineness of the modified powder is 60-80 mesh.
[0020] Further, in step (3), the ratio of the precursor powder to anhydrous ethanol containing the dissolved silane coupling agent is 1 g: 5~10 mL. Optionally, the mass fraction of the silane coupling agent in the anhydrous ethanol is 0.3~0.4%.
[0021] Further, in step (3), the silane coupling agent includes at least one of KH550, KH560, KH580, KH171, etc.
[0022] Furthermore, in step (3), the mass fraction of tetraethoxysilane in the anhydrous ethanol is 9-12%.
[0023] Further, in step (4), the proportions of cement, coarse aggregate, fine aggregate, silica fume, modified calcium carbide slag powder, and microcrack self-healing agent are 100~115 parts by weight: 230~265 parts by weight: 140~170 parts by weight: 10~20 parts by weight: 10~15 parts by weight: 3~6 parts by weight.
[0024] Furthermore, in step (4), the mass ratio of the water to the total of cement and silica fume is 0.38~0.43:1.
[0025] Further, in step (4), the modified carbide slag powder is prepared by the following method: after forming a slurry with carbide slag powder and water, carbon dioxide is continuously introduced into it and stirred continuously. After completion, the water is removed by drying and grinding to obtain the modified carbide slag powder.
[0026] Furthermore, the ratio of the calcium carbide slag powder to water is 1g:20~35mL.
[0027] Furthermore, the carbon dioxide is introduced at a rate of 4-7 L / min for a duration of 6-8 hours.
[0028] Further, the drying temperature is 90~110℃. Optionally, the fineness of the modified calcium carbide slag powder is 220~300 mesh.
[0029] Compared with the prior art, the technical solution of the present invention has at least the following beneficial effects:
[0030] (1) This invention uses mesoporous silica as a carrier, loads magnesium hydroxide therein, and then performs calcination treatment together, thereby not only converting magnesium hydroxide into magnesium oxide, but also achieving thermal activation of the mesoporous silica to form the active powder. Further, this invention grinds the active powder together with powdered polycarboxylate superplasticizer and potassium dihydrogen phosphate powder, and then coats it with polyethylene glycol to form a precursor powder. Finally, this invention uses a silane coupling agent to load tetraethoxysilane on the particle surface of the precursor powder to form a microcrack self-healing agent. After being added to concrete materials, on the one hand, the self-healing agent can not only form a good bond with the concrete matrix by utilizing the silane coupling agent on its surface, but also utilizes the alkaline environment provided by the concrete matrix to hydrolyze the tetraethoxysilane on the surface of the self-healing agent to form nano-silica, which further reacts with the hydration product calcium hydroxide in the concrete matrix to form hydrated calcium silicate gel, thereby making the self-healing agent of this invention more firmly bonded to the concrete matrix. This not only helps improve the strength of the concrete matrix but also helps tear the self-healing agent when microcracks appear in the concrete matrix, achieving efficient activation of the self-healing mechanism by utilizing the generation of microcracks. This allows the components of the self-healing agent to be more precisely exposed at the microcrack interface. Magnesium oxide and potassium dihydrogen phosphate react rapidly with the presence of moisture in the microcracks to form a high-strength, highly adhesive product that repairs the microcracks and prevents their further expansion. On the other hand, the highly active mesoporous silica can react with the calcium hydroxide provided by the concrete matrix to form hydrated calcium silicate gel, which can further repair the microcracks. During this process, the polycarboxylate superplasticizer can use its abundant carboxyl groups to capture calcium ions provided by the calcium hydroxide and residual calcium hydroxide in the modified carbide slag powder, promoting the reaction of the mesoporous silica. Furthermore, the residual magnesium oxide, under the action of the water film constructed by the polycarboxylate superplasticizer on its surface, can accelerate the hydration of magnesium oxide. The resulting expansive product, magnesium hydroxide, can fill the microcracks, further enhancing the repair effect.
[0031] (2) The present invention also uses carbide slag as raw material, prepares it into slurry and then passes carbon dioxide through it for treatment, thereby converting calcium hydroxide in it into calcium carbonate and realizing the utilization of carbon dioxide. The micro powder formed after grinding can not only fill the micropores in concrete, improve the density of concrete matrix, reduce the tendency of microcracks caused by volume changes due to temperature changes and drying shrinkage, but also improve the mechanical properties of concrete matrix. Attached Figure Description
[0032] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention and do not constitute an undue limitation of the invention.
[0033] Figure 1 The image shows a sample of the microcrack self-healing agent prepared in Example 1 below.
[0034] Figure 2 The following is a diagram showing the compressive strength test results for Example 1.
[0035] Figure 3 The image shows a sample of the microcrack self-healing agent prepared in Example 2 below.
[0036] Figure 4 The image shows a sample of the microcrack self-healing agent prepared in Example 3 below. Detailed Implementation
[0037] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as those skilled in the art. The preferred embodiments and materials described in this invention are for illustrative purposes only. The technical solutions of the present invention will now be further described with reference to specific embodiments.
[0038] Example 1: A process for preparing a concrete material with both carbon reduction and microcrack self-healing functions, comprising the following steps:
[0039] (1) Mesoporous silica powder and 3.5 mol / L magnesium sulfate solution were mixed at a ratio of 1 g: 7 mL and stirred continuously for 20 min. Then, sodium hydroxide solution was added to the resulting mixture, with a molar ratio of sodium hydroxide to magnesium ions in the magnesium sulfate solution of 2.1:1. After stirring evenly, the mixture was allowed to stand for 10 min. The solid product was then filtered out and washed with water to remove residual alkali. The resulting solid product was then heated to 540 °C and calcined for 30 min. After calcination, the mixture was cooled to room temperature to obtain MgO@mesoporous silica active powder.
[0040] (2) Powdered polycarboxylate superplasticizer, potassium dihydrogen phosphate powder and the active powder were mixed in a ratio of 0.15g:1.2g:20g and ground for 30min. Then the mixture was passed through a 60-mesh sieve. The modified powder was added to anhydrous ethanol containing polyethylene glycol in a ratio of 1g:8mL. The mass fraction of polyethylene glycol in the anhydrous ethanol was 25%. After stirring evenly, the mixture was spray-dried to obtain the precursor powder.
[0041] (3) The precursor powder and anhydrous ethanol with a mass fraction of 0.3% of silane coupling agent (KH550) are mixed at a ratio of 1g:8mL and stirred evenly. Then, the substance is added at a mass fraction of 10% of tetraethoxysilane in the anhydrous ethanol and stirred evenly. The resulting solid-liquid mixture is then spray-dried to obtain the microcrack self-repairing agent.
[0042] (4) Mix calcium carbide slag powder with water at a ratio of 1g:25mL and stir to form a slurry. Then, continuously introduce carbon dioxide into the slurry at a rate of 5L / min for 7.5 hours, and stir continuously during this process. After completion, heat and dry at 100℃ to remove moisture. Then grind the solid product and pass it through a 300-mesh sieve to obtain modified calcium carbide slag powder.
[0043] (5) Take the following raw materials in the following proportions: 110 parts by weight of PO 42.5 cement, 245 parts by weight of coarse aggregate, 160 parts by weight of fine aggregate, 13 parts by weight of silica fume, 12 parts by weight of modified calcium carbide slag powder of this embodiment, and 4.5 parts by weight of microcrack self-healing agent of this embodiment. Mix the above raw materials and stir for 2 minutes, then add 49.5 parts by weight of water and stir evenly to obtain concrete material.
[0044] Performance testing: The compressive strength recovery rate of the concrete material prepared in this embodiment was tested according to the method in "4.4 Self-healing test of concrete under load damage" of the "Standard for Test Method of Self-healing Performance of Cement Concrete" (TCECS 913-2021). The result is λ. p =126.1%.
[0045] Example 2: A process for preparing a concrete material with both carbon reduction and microcrack self-healing functions, comprising the following steps:
[0046] (1) Mesoporous silica powder and 2 mol / L magnesium nitrate solution were mixed at a ratio of 1 g: 8.5 mL and stirred continuously for 25 min. Then, sodium hydroxide solution was added to the resulting mixture, with a molar ratio of sodium hydroxide to magnesium ions in the magnesium nitrate solution of 2.1:1. After stirring evenly, the mixture was allowed to stand for 15 min. The solid product was then filtered out and washed with water to remove residual alkali. The resulting solid product was then heated to 580 °C and calcined for 30 min. After calcination, the mixture was cooled to room temperature to obtain MgO@mesoporous silica active powder.
[0047] (2) Powdered polycarboxylate superplasticizer, potassium dihydrogen phosphate powder and the active powder were mixed in a ratio of 0.16g:1.45g:25g and ground for 30min. Then the mixture was passed through an 80-mesh sieve. The modified powder was added to anhydrous ethanol containing polyethylene glycol in a ratio of 1g:10mL. The mass fraction of polyethylene glycol in the anhydrous ethanol was 20%. After stirring evenly, the mixture was spray-dried to obtain the precursor powder.
[0048] (3) The precursor powder and anhydrous ethanol with a mass fraction of 0.4% of silane coupling agent (KH580) are mixed at a ratio of 1g:5mL and stirred evenly. Then, the substance is added at a mass fraction of 9% of tetraethoxysilane in the anhydrous ethanol and stirred evenly. The resulting solid-liquid mixture is then spray-dried to obtain the microcrack self-repairing agent.
[0049] (4) Mix calcium carbide slag powder with water at a ratio of 1g:20mL and stir to form a slurry. Then, continuously introduce carbon dioxide into the slurry at a rate of 7L / min for 6 hours, and stir continuously during the process. After completion, heat and dry at 110℃ to remove moisture. Then grind the solid product and pass it through a 250-mesh sieve to obtain modified calcium carbide slag powder.
[0050] (5) Take the following raw materials in the following proportions: 100 parts by weight of PO 42.5 cement, 230 parts by weight of coarse aggregate, 140 parts by weight of fine aggregate, 10 parts by weight of silica fume, 10 parts by weight of modified calcium carbide slag powder of this embodiment, and 3 parts by weight of microcrack self-healing agent of this embodiment. Mix the above raw materials and stir for 2 minutes, then add 41.8 parts by weight of water and stir evenly to obtain concrete material.
[0051] Performance testing: The compressive strength recovery rate of the concrete material prepared in this embodiment was tested using the same method as in Example 1 above, and the result was λ. p =118.9%.
[0052] Example 3: A process for preparing a concrete material with both carbon reduction and microcrack self-healing functions, comprising the following steps:
[0053] (1) Mesoporous silica powder and 4 mol / L magnesium chloride solution were mixed at a ratio of 1 g: 6 mL and stirred continuously for 30 min. Then, sodium hydroxide solution was added to the resulting mixture, with a molar ratio of sodium hydroxide to magnesium ions in the magnesium chloride solution of 2:1. After stirring evenly, the mixture was allowed to stand for 15 min. The solid product was then filtered out and washed with water to remove residual alkali. The resulting solid product was then heated to 520 °C and calcined for 40 min. After calcination, the mixture was cooled to room temperature to obtain MgO@mesoporous silica active powder.
[0054] (2) Powdered polycarboxylate superplasticizer, potassium dihydrogen phosphate powder and the active powder were mixed in a ratio of 0.12g:1.0g:25g and ground for 30min. Then the mixture was passed through a 60-mesh sieve. The modified powder was added to anhydrous ethanol containing polyethylene glycol in a ratio of 1g:5mL. The mass fraction of polyethylene glycol in the anhydrous ethanol was 30%. After stirring evenly, the mixture was spray-dried to obtain the precursor powder.
[0055] (3) The precursor powder and anhydrous ethanol with a mass fraction of 0.35% of silane coupling agent (KH171) are mixed at a ratio of 1g:10mL and stirred evenly. Then, the substance is added at a mass fraction of 12% of tetraethoxysilane in the anhydrous ethanol and stirred evenly. The resulting solid-liquid mixture is then spray-dried to obtain the microcrack self-repairing agent.
[0056] (4) Mix calcium carbide slag powder with water at a ratio of 1g:35mL and stir to form a slurry. Then, continuously introduce carbon dioxide into the slurry at a rate of 4L / min for 8 hours, and stir continuously during the process. After completion, heat and dry at 90℃ to remove moisture. Then grind the solid product and pass it through a 200-mesh sieve to obtain modified calcium carbide slag powder.
[0057] (5) Take the following raw materials in the following proportions: 115 parts by weight of PO 42.5 cement, 265 parts by weight of coarse aggregate, 170 parts by weight of fine aggregate, 20 parts by weight of silica fume, 15 parts by weight of modified calcium carbide slag powder of this embodiment, and 6 parts by weight of microcrack self-healing agent of this embodiment. Mix the above raw materials and stir for 2 minutes, then add 58 parts by weight of water and stir evenly to obtain concrete material.
[0058] Performance testing: The compressive strength recovery rate of the concrete material prepared in this embodiment was tested using the same method as in Example 1 above, and the result was λ. p =114.7%.
[0059] Example 4: A concrete material preparation process with both carbon reduction and microcrack self-healing functions, the same as Example 1 above, except that the microcrack self-healing agent in this example is prepared by the following method:
[0060] (1) Mesoporous silica powder and 3.5 mol / L magnesium sulfate solution were mixed at a ratio of 1 g: 7 mL and stirred continuously for 20 min. Then, sodium hydroxide solution was added to the resulting mixture, with a molar ratio of sodium hydroxide to magnesium ions in the magnesium sulfate solution of 2.1:1. After stirring evenly, the mixture was allowed to stand for 10 min. The solid product was then filtered out and washed with water to remove residual alkali. The resulting solid product was then heated to 540 °C and calcined for 30 min. After calcination, the mixture was cooled to room temperature to obtain MgO@mesoporous silica active powder.
[0061] (2) Mix the powdered polycarboxylate superplasticizer, potassium dihydrogen phosphate powder and the active powder in a ratio of 0.15g:1.2g:20g, grind for 30 minutes, and then pass through a 60-mesh sieve. Add the obtained modified powder to anhydrous ethanol containing polyethylene glycol in a ratio of 1g:8mL, where the mass fraction of polyethylene glycol in the anhydrous ethanol is 25%. After stirring evenly, spray dry to obtain the microcrack self-repairing agent.
[0062] Performance testing: The compressive strength recovery rate of the concrete material prepared in this embodiment was tested using the same method as in Example 1 above, and the result was λ. p =102.5%.
[0063] Example 5: A process for preparing a concrete material with both carbon reduction and microcrack self-healing functions, comprising the following steps:
[0064] (1) Mesoporous silica powder and 3.5 mol / L magnesium sulfate solution were mixed at a ratio of 1 g: 7 mL and stirred continuously for 20 min. Then, sodium hydroxide solution was added to the resulting mixture, with a molar ratio of sodium hydroxide to magnesium ions in the magnesium sulfate solution of 2.1:1. After stirring evenly, the mixture was allowed to stand for 10 min. The solid product was then filtered out and washed with water to remove residual alkali. The resulting solid product was then heated to 540 °C and calcined for 30 min. After calcination, the mixture was cooled to room temperature to obtain MgO@mesoporous silica active powder.
[0065] (2) Take the following raw materials in the following proportions: 110 parts by weight of PO 42.5 cement, 245 parts by weight of coarse aggregate, 160 parts by weight of fine aggregate, 13 parts by weight of silica fume, 12 parts by weight of the modified calcium carbide slag powder of Example 1 above, and 4.5 parts by weight of the MgO@mesoporous silica active powder of this example. Mix the above raw materials and stir for 2 minutes, then add 49.5 parts by weight of water and stir evenly to obtain concrete material.
[0066] Performance testing: The compressive strength recovery rate of the concrete material prepared in this embodiment was tested using the same method as in Example 1 above, and the result was λ. p =73.8%.
[0067] Example 6: A concrete material preparation process with both carbon reduction and microcrack self-healing functions, the same as Example 2 above, except that the microcrack self-healing agent in this example is prepared by the following method:
[0068] (1) Mesoporous silica powder and 2 mol / L magnesium nitrate solution were mixed at a ratio of 1 g: 8.5 mL and stirred continuously for 25 min. Then, sodium hydroxide solution was added to the resulting mixture, with a molar ratio of sodium hydroxide to magnesium ions in the magnesium nitrate solution of 2.1:1. After stirring evenly, the mixture was allowed to stand for 15 min. The solid product was then filtered out and washed with water to remove residual alkali. The resulting solid product was then heated to 580 °C and calcined for 30 min. After calcination, the mixture was cooled to room temperature to obtain MgO@mesoporous silica active powder.
[0069] (2) Potassium dihydrogen phosphate powder and the active powder were mixed in a ratio of 1.45g:25g and ground for 30min. The mixture was then passed through an 80-mesh sieve. The resulting modified powder was added to anhydrous ethanol containing polyethylene glycol in a ratio of 1g:10mL. The mass fraction of polyethylene glycol in the anhydrous ethanol was 20%. After stirring evenly, the mixture was spray-dried to obtain the precursor powder.
[0070] (3) The precursor powder and anhydrous ethanol with a mass fraction of 0.4% of silane coupling agent (KH580) are mixed at a ratio of 1g:5mL and stirred evenly. Then, the substance is added at a mass fraction of 9% of tetraethoxysilane in the anhydrous ethanol and stirred evenly. The resulting solid-liquid mixture is then spray-dried to obtain the microcrack self-repairing agent.
[0071] Performance testing: The compressive strength recovery rate of the concrete material prepared in this embodiment was tested using the same method as in Example 1 above, and the result was λ. p =105.2%.
[0072] Example 7: A concrete material preparation process with both carbon reduction and microcrack self-healing functions, the same as Example 3 above, except that the microcrack self-healing agent in this example is prepared by the following method:
[0073] (1) Mix silica powder with 4 mol / L magnesium chloride solution at a ratio of 1 g: 6 mL and stir continuously for 30 min. Then add sodium hydroxide solution to the resulting mixture, with a molar ratio of sodium hydroxide to magnesium ions in the magnesium chloride solution of 2:1. After stirring evenly, let stand for 15 min, then filter out the solid product and wash with water to remove residual alkali. Then heat the obtained solid product to 520℃ and calcine for 40 min. After completion, cool to room temperature to obtain MgO@silica active powder.
[0074] (2) Powdered polycarboxylate superplasticizer, potassium dihydrogen phosphate powder and the active powder were mixed in a ratio of 0.12g:1.0g:25g and ground for 30min. Then the mixture was passed through a 60-mesh sieve. The modified powder was added to anhydrous ethanol containing polyethylene glycol in a ratio of 1g:5mL. The mass fraction of polyethylene glycol in the anhydrous ethanol was 30%. After stirring evenly, the mixture was spray-dried to obtain the precursor powder.
[0075] (3) The precursor powder and anhydrous ethanol with a mass fraction of 0.35% of silane coupling agent (KH171) are mixed at a ratio of 1g:10mL and stirred evenly. Then, the substance is added at a mass fraction of 12% of tetraethoxysilane in the anhydrous ethanol and stirred evenly. The resulting solid-liquid mixture is then spray-dried to obtain the microcrack self-repairing agent.
[0076] Performance testing: The compressive strength recovery rate of the concrete material prepared in this embodiment was tested using the same method as in Example 1 above, and the result was λ. p =96.4%.
[0077] Example 8: A concrete material preparation process with both carbon reduction and microcrack self-healing functions, the same as Example 2 above, except that the microcrack self-healing agent in this example is prepared by the following method:
[0078] (1) Mesoporous silica powder and 2 mol / L magnesium nitrate solution were mixed at a ratio of 1 g: 8.5 mL and stirred continuously for 25 min. Then, sodium hydroxide solution was added to the resulting mixture, with a molar ratio of sodium hydroxide to magnesium ions in the magnesium nitrate solution of 2.1:1. After stirring evenly, the mixture was allowed to stand for 15 min. The solid product was then filtered out and washed with water to remove residual alkali. The solid product was then dried to obtain Mg(OH)2@mesoporous silica powder.
[0079] (2) Powdered polycarboxylate superplasticizer, potassium dihydrogen phosphate powder, and Mg(OH)2@mesoporous silica powder were mixed in a ratio of 0.16g:1.45g:25g and ground for 30min. The mixture was then passed through an 80-mesh sieve. The resulting modified powder was added to anhydrous ethanol containing dissolved polyethylene glycol in a ratio of 1g:10mL. The mass fraction of polyethylene glycol in the anhydrous ethanol was 20%. After stirring evenly, the mixture was spray-dried to obtain the precursor powder.
[0080] (3) The precursor powder and anhydrous ethanol with a mass fraction of 0.4% of silane coupling agent (KH580) are mixed at a ratio of 1g:5mL and stirred evenly. Then, the substance is added at a mass fraction of 9% of tetraethoxysilane in the anhydrous ethanol and stirred evenly. The resulting solid-liquid mixture is then spray-dried to obtain the microcrack self-repairing agent.
[0081] Performance testing: The compressive strength recovery rate of the concrete material prepared in this embodiment was tested using the same method as in Example 1 above, and the result was λ. p =81.6%.
[0082] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., should be included within the protection scope of the present invention.
Claims
1. A process for preparing concrete materials that combines carbon reduction and microcrack self-healing functions, characterized in that, Includes the following steps: (1) After mixing mesoporous silica powder with a solution containing magnesium ion source, the mixture is stirred and then an alkaline solution is added and allowed to stand. After the mixture is finished, the residual alkaline solution is washed away and then calcined to obtain MgO@mesoporous silica active powder. (2) The powdered polycarboxylate superplasticizer, potassium dihydrogen phosphate powder and the active powder are mixed and ground. Then the modified powder is added to anhydrous ethanol containing polyethylene glycol, stirred evenly and spray-dried to obtain precursor powder. (3) The precursor powder is mixed with anhydrous ethanol containing silane coupling agent and stirred. Then tetraethoxysilane is added and stirred evenly. Then spray-drying is performed to obtain microcrack self-healing agent. (4) Using cement, coarse aggregate, fine aggregate, silica fume, modified calcium carbide slag powder, and the microcrack self-healing agent as raw materials, mix them and add water and stir evenly to obtain the concrete material; the modified calcium carbide slag powder is prepared by the following method: calcium carbide slag powder and water form a slurry, then continuously introduce carbon dioxide into it and stir continuously. After completion, dry to remove moisture and grind to obtain the modified calcium carbide slag powder.
2. The concrete material preparation process with both carbon reduction and microcrack self-healing functions according to claim 1, characterized in that, In step (1), the ratio of the mesoporous silica powder to the solution containing the magnesium ion source is 1g:6~8.5mL.
3. The concrete material preparation process with both carbon reduction and microcrack self-healing functions according to claim 1, characterized in that, In step (1), the concentration of the magnesium ion source in the solution is 2~4 mol / L.
4. The concrete material preparation process with both carbon reduction and microcrack self-healing functions according to claim 1, characterized in that, In step (1), the magnesium ion source includes at least one of magnesium chloride, magnesium sulfate, and magnesium nitrate.
5. In the concrete material preparation process with carbon reduction and microcrack self-repair function according to claim 1, the mixing time in step (1) is 20~30min.
6. The concrete material preparation process with both carbon reduction and microcrack self-healing functions according to claim 1, characterized in that, In step (1), the molar ratio of hydroxide ions to magnesium ions in the alkaline solution is 2~2.1:
1.
7. The concrete material preparation process with both carbon reduction and microcrack self-healing functions according to claim 1, wherein in step (1), the alkaline solution comprises: At least one of sodium hydroxide, potassium hydroxide, and ammonia water.
8. In the concrete material preparation process with carbon reduction and microcrack self-healing functions according to claim 1, the standing time in step (1) is 10~15min.
9. The concrete material preparation process with both carbon reduction and microcrack self-healing functions according to claim 1, characterized in that, In step (1), the calcination treatment is carried out at a temperature of 520~580℃ for 30~40 minutes.
10. The concrete material preparation process with both carbon reduction and microcrack self-healing functions according to claim 1, characterized in that, In step (2), the ratio of the powdered polycarboxylate superplasticizer, potassium dihydrogen phosphate powder, and active powder is 0.12~0.16g: 1~1.45g: 20~25g.
11. The concrete material preparation process with both carbon reduction and microcrack self-healing functions according to claim 1, characterized in that, In step (2), the ratio of the modified powder to anhydrous ethanol containing polyethylene glycol is 1g: 5~10mL.
12. In the concrete material preparation process with carbon reduction and microcrack self-healing functions according to claim 1, in step (2), the mass fraction of polyethylene glycol in the anhydrous ethanol is 20~30%.
13. In the concrete material preparation process with carbon reduction and microcrack self-repair function according to claim 1, in step (2), the fineness of the modified powder is 60~80 mesh.
14. The concrete material preparation process with both carbon reduction and microcrack self-healing functions according to claim 1, characterized in that, In step (3), the ratio of the precursor powder to anhydrous ethanol containing silane coupling agent is 1g: 5~10mL.
15. In the concrete material preparation process with carbon reduction and microcrack self-repair function according to claim 1, in step (3), the mass fraction of silane coupling agent in the anhydrous ethanol is 0.3~0.4%.
16. The concrete material preparation process with both carbon reduction and microcrack self-healing functions according to claim 1, wherein in step (3), the silane coupling agent comprises: At least one of KH550, KH560, KH580, and KH171.
17. In the concrete material preparation process with carbon reduction and microcrack self-repair function according to claim 1, in step (3), the mass fraction of tetraethoxysilane in the anhydrous ethanol is 9~12%.
18. The concrete material preparation process with both carbon reduction and microcrack self-healing functions according to claim 1, characterized in that, In step (4), the proportions of the cement, coarse aggregate, fine aggregate, silica fume, modified carbide slag powder, and microcrack self-healing agent are 100~115 parts by weight: 230~265 parts by weight: 140~170 parts by weight: 10~20 parts by weight: 10~15 parts by weight: 3~6 parts by weight.
19. In the concrete material preparation process with carbon reduction and microcrack self-repair function according to claim 1, in step (4), the mass ratio of water to cement and silica fume is 0.38~0.43:
1.
20. The concrete material preparation process with both carbon reduction and microcrack self-healing functions according to any one of claims 1-19, characterized in that, In the preparation method of modified calcium carbide slag powder, the ratio of calcium carbide slag powder to water is 1g:20~35mL.
21. The concrete material preparation process with both carbon reduction and microcrack self-healing functions according to any one of claims 1-19, characterized in that, In the preparation method of modified calcium carbide slag powder, the carbon dioxide is introduced at a rate of 4-7 L / min for a duration of 6-8 hours.
22. The concrete material preparation process with both carbon reduction and microcrack self-healing functions according to any one of claims 1-19, characterized in that, In the preparation method of modified calcium carbide slag powder, the drying temperature is 90~110℃.
23. The concrete material preparation process with both carbon reduction and microcrack self-healing functions according to any one of claims 1-19, characterized in that, The modified calcium carbide slag powder has a fineness of 220~300 mesh.