Self-repairing cement-based material and application thereof

Abstract

The invention aims to provide a self-repairable cement-based material and application thereof, and belongs to the technical field of mining fire prevention and extinguishing materials, the self-repairable cement-based material comprises a gel material, a complexing agent, an active chemical material and a catalytic solvent, the mass of the complexing agent is 40% of the mass of the gel material, and the mass of the active chemical material is 40% of the mass of the gel material. The mass of the active chemical material is 60% of that of the gel material, and the mass of the catalytic solvent is 40-50% of the total mass of the gel material, the complexing agent and the active chemical material. The preparation method of the self-repairable cement-based material is simple and easy to operate, the prepared self-repairable cement-based material has the advantages of being low in cost, good in fluidity, high in self-repairing efficiency and good in repairing effect, and the fire preventing and extinguishing effect can be achieved in the mode of blocking air and isolating oxygen at the three stages before solidification, after solidification and after cracking repairing.

Description

Technical Field

[0001] The invention belongs to the technical field of fire-proof and extinguishing materials for mines, and in particular relates to a self-repairing cement-based material and application thereof. Background Art

[0002] Cement-based materials are used in civil engineering, water conservancy, and even in underground goaf filling to prevent spontaneous combustion of coal due to their wide range of raw materials, low cost, high strength, and durability. However, since it is a brittle material, it will produce tiny cracks or even cracks in the environment due to the combined effects of temperature, humidity, concrete shrinkage, and various load conditions.

[0003] Cement-based self-healing materials refer to technologies that use the material's own properties to repair cracks without external repair measures. With the development of materials science and biology, related self-healing technologies have developed extremely rapidly, among which the differences in triggering mechanisms, triggering efficiencies, limiting conditions, application purposes, and repair mechanisms have led to different repair effects and application fields.

[0004] At present, my country is a country with a large number of coal resources, as well as a large coal production and consumption country. In the future, the status of coal as my country's main energy source will not change for a long time. In the process of coal mining, the spontaneous combustion of coal left in the goaf directly affects the safe and efficient mining of coal mines. Using plugging materials to seal the air leakage channel is an effective way to solve the problem of spontaneous combustion of coal in the goaf.

[0005] Based on the above analysis, cement-based materials have the advantages of low cost and strong durability, and are therefore widely used in underground goaf filling and fire prevention and extinguishing. However, they have the disadvantage of being brittle and will lead to cracking in the later stage, and cannot guarantee the durability of fire prevention and extinguishing. Therefore, the present invention proposes a self-repairing cement-based material. Summary of the invention

[0006] In view of the problem that existing cement-based materials crack in the later stage and cannot ensure the durability of fire protection and extinguishing, the present invention provides a self-repairing cement-based material and its application. This material has low cost, high repair efficiency and good repair effect, and can solve the problem of cracking of current cement-based materials after solidification, and ensure the sustainability of the material's function.

[0007] The present invention adopts the following technical solution: A self-repairable cement-based material comprises a gel material, a chelating agent, an active chemical material and a catalytic solvent, wherein the mass of the chelating agent is 40% of the mass of the gel material, the mass of the active chemical material is 60% of the mass of the gel material, and the mass of the catalytic solvent is 40-50% of the total mass of the gel material, the chelating agent and the active chemical material.

[0008] Furthermore, the gel material is cement.

[0009] Furthermore, the complexing agent is an amino acid complexing agent.

[0010] Furthermore, the complexing agent is ethylenediaminetetraacetic acid.

[0011] Furthermore, the active chemical material includes a primary active chemical material and a secondary active chemical material, wherein the primary active chemical material includes a soluble carbonate and an insoluble carbonate, and the secondary active chemical material includes a soluble silicate.

[0012] Furthermore, the soluble carbonate includes sodium carbonate, the insoluble carbonate includes calcium carbonate, and the soluble silicate includes sodium silicate.

[0013] Furthermore, the mass ratio of the sodium carbonate, calcium carbonate and sodium silicate is 1:1:1.

[0014] Furthermore, the catalyst is pure water.

[0015] A self-repairing cement-based material is used for fire prevention and extinguishing in goaf areas of mines.

[0016] A method for preparing a self-repairable cement-based material comprises the following steps: fully mixing a weighed gel material, a complexing agent, and an active chemical material under continuous stirring to obtain a solid material; in this step, the components are mixed together in a physical form without any reaction; Add the catalytic solvent to the mixed solid materials, mix the materials thoroughly under constant stirring, and wait for the reaction to be completed. This step is accompanied by exothermic reaction, complex reaction, acid-base neutralization reaction, and precipitation reaction.

[0017] The preparation method of the self-repairing cement-based material of the present invention has a simple process, and the prepared cement-based self-repairing material has the characteristics of high repair efficiency and good repair effect. The complexing agent is ethylenediaminetetraacetic acid, and the chemical formula is C 10 H 16 N 2 O 8 It is composed of an all-nitrogen ethylenediamine main body and four carboxyl ligands, which can complex the free calcium ions in cement, Ca 2+ Complexing agent for Ca 2+ It has a strong chelating effect, which delays the early hydration process of cement, resulting in a large amount of unhydrated cement in the self-repairing cement-based material after solidification. When cracks appear in the self-repairing cement-based material, under the action of water and carbon dioxide in the air, hydration products will continue to be generated and fill the cracks, thereby promoting crack healing.

[0018] The active chemical materials include main active chemical materials and secondary active chemical materials. The main active chemical materials are sodium carbonate and calcium carbonate. Calcium carbonate can make other materials have better dispersibility in cement when mixed; make the microstructure of CSH gel generated by cement hydration more compact; and can form a more compact structure with the repaired product. This is because calcium carbonate can react with ethylenediaminetetraacetic acid to generate carbon dioxide and calcium complex when adding water, and the formed complex can react with CO 3 2- , HCO 3 - 、SiO 3 2- The substances react to form CaCO 3 , complete the complexation-precipitation reaction, promote the further hydration reaction, and thus generate more CSH. Sodium carbonate can react with Ca(OH) 2 The reaction generates CaCO 3 The EDTA is precipitated, and the generated NaOH can ensure the alkalinity of cement-based composite materials and promote the further occurrence of cement hydration reaction; since EDTA is soluble in sodium carbonate solution and reacts with it to produce carbon dioxide and EDTA sodium salt, and EDTA sodium salt has the same property of complexing calcium ions as EDTA, sodium carbonate can better disperse EDTA in the material, so that it can fully complex calcium ions, and to a certain extent promote the self-healing performance of the material; the secondary active chemical material is sodium silicate, and the soluble silicate substances can directly react with Ca in cement. 2+ A precipitation reaction occurs to generate CSH, which improves the strength and durability of the cement after solidification. It can also react with unhydrated cement to generate calcium silicate gel after the cement-based material cracks, thereby improving the strength and durability of the repair and enhancing the repair effect.

[0019] The amount of complexing agent used will affect the early hydration process of cement. Although sodium carbonate will react partially, sodium ethylenediaminetetraacetic acid sodium salt also has a complexing effect, so the consumption of sodium carbonate on the complexing agent is not considered. Although calcium carbonate will also react with the complexing agent, considering the renewability and indispensability of calcium carbonate, the mass of the complexing agent is 40% of the mass of the gel material, and the mass of the active chemical material is 60% of the mass of the gel material. The mass ratio of the active chemical material is (1:1:1), that is, the mass ratio of the solid material is (5:2:1:1:1).

[0020] When selecting a solvent, in order to achieve a good combination of various materials, to reduce costs, and to make the production process green and environmentally friendly, preferably, the solvent is pure water.

[0021] The amount of solvent used will affect the fluidity, setting time, repair efficiency and repair effect of the self-repairable cement-based material. Preferably, the mass of the catalytic solvent is 40%~50% of the mass of the solid material, that is, the water-solid mass ratio is (0.8~1):2.

[0022] Since the appropriate water-solid ratio makes the cement-based material have good fluidity, grouting technology can be used to fill the underground goaf; The prepared cement-based material is filled into the air leaks in the underground goaf, and oxygen is isolated by blocking the air leaks to achieve the effect of fire prevention and extinguishing. This material can also be filled into the area where spontaneous combustion has occurred in the underground goaf, and the fire that has started can be extinguished by isolating oxygen and cooling it down.

[0023] The three-stage oxygen isolation, before solidification, the prepared cement-based material contains non-combustible solids and liquids which can isolate oxygen by themselves; after solidification, this material can also isolate oxygen due to its dense solid structure; when cracks occur in the solidified cement-based material, this cement-based material has extremely high efficient self-repairing ability and can quickly isolate oxygen again, thereby achieving the effect of fire prevention and extinguishing.

[0024] The beneficial effects of the present invention are as follows: 1. The present invention adds chelating agents and other active chemical materials to cement, and uses water as a catalytic solvent. While improving the performance, a highly efficient cement-based self-repairing material is prepared, which solves the technical problem of cracking and ensures the continuity of fire prevention and extinguishing.

[0025] 2. The self-repairable cement-based material prepared by the present invention can be applied to different scenarios according to different water-to-solid mass ratios, has good fluidity, and can achieve fire prevention and extinguishing effects by blocking leaks and isolating oxygen in three stages: before solidification, after solidification, and after crack repair.

[0026] 3. The self-repairable cement-based material prepared in the present application has the advantages of low cost, simple preparation, easy availability of raw materials, high self-repair efficiency and good repair effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The present invention is a process flow chart for preparing the self-repairing cement-based material; Figure 2 Schematic diagram of air isolation capability after crack repair in Examples 1-3 of the present invention; Figure 3 This is a high-definition microscopic diagram of cracks before and after repair in Example 1 of the present invention, wherein a is before repair and b is after repair; Figure 4This is a high-definition microscopic diagram of cracks before and after repair in Example 2 of the present invention, where a is before repair and b is after repair; Figure 5 This is a high-definition microscopic diagram of Example 3 of the present invention before and after crack repair, wherein a is before repair and b is after repair. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] The ethylenediaminetetraacetic acid is Chinese medicine (AR analytical grade), and the sodium carbonate is Chinese medicine (AR analytical grade) anhydrous sodium carbonate, with the chemical formula of Na 2 CO 3 The calcium carbonate is Chinese medicine (AR analytical grade), and its chemical formula is CaCO 3 The sodium silicate is national medicine (AR analytical grade) sodium silicate nine hydrate, the chemical formula is Na 2 SiO 3 ∙9H 2 O.

[0030] Example 1 The method for the self-repairing effect verification experiment of the self-repairable cement-based material of this embodiment comprises the following steps: S1: Weigh 50g of cement, 20g of EDTA, 10g of sodium silicate, 10g of sodium carbonate and 10g of calcium carbonate in a mass ratio of (5:2:1:1:1), add them into a container and mix thoroughly under constant stirring; S2: Weigh 50g of pure water at a water-to-solid mass ratio of (1:2) and pour it into the container containing the solid material in two portions while stirring continuously; S3: After the solid material and the liquid material are fully mixed and no gas is generated, the self-repairing cement-based material is obtained; S4: pouring the prepared self-repairing cement-based material into the prepared mold, sealing it with plastic wrap and culturing it for 14 days before demolding it; S5: Artificially create cracks on the demoulding sample and expose it to air for 7 days to self-heal.

[0031] The self-repairable cement-based material of this embodiment is prepared by the above-mentioned preparation method.

[0032] Example 2 The method steps of the self-healing effect verification experiment of the self-healing cement-based material of this embodiment are different from those of Example 1 in that: in step S2, 45g of pure water is weighed according to the water-to-solid mass ratio of (9:20), and the rest is the same as in Example 1.

[0033] The self-repairable cement-based material of this embodiment is prepared by the above-mentioned preparation method.

[0034] Example 3 The method steps of the self-healing effect verification experiment of the self-healing cement-based material of this embodiment are different from those of Example 1 in that: in step S2, 40g of pure water is weighed according to the water-to-solid mass ratio of (2:5), and the rest is the same as in Example 1.

[0035] The self-repairable cement-based material of this embodiment is prepared by the above-mentioned preparation method.

[0036] Performance testing 1. Take the samples after the cracks in Examples 1-3 are repaired to test the air isolation ability. The test results are as follows: Figure 2 shown.

[0037] 2. Take samples of Examples 1-3 before and after crack repair and observe the repair status. Figure 3 , 4 , as shown in Figure 5.

[0038] Results Analysis Analyze Examples 1-3 and combine Figure 2 It can be seen that the water-to-solid mass ratio adopted in this application can achieve the effect of isolating the material from air after cracking and repair.

[0039] Further analysis of Examples 1-3 and combined Figure 3 , 4 , 5 It can be seen that the water-to-solid mass ratio adopted in this application can enable the material to self-repair after cracking.

[0040] In summary, the self-repairable cement-based material prepared in the present application can ensure the continuity of fire prevention and extinguishing by isolating oxygen.

[0041] This specific embodiment is only an explanation of the present application, and it is not a limitation of the present application. After reading this specification, those skilled in the art can make non-creative modifications to the present embodiment as needed, but as long as it is within the scope of the claims of the present application, it is protected by the patent law.

Claims

1. A self-repairing cement-based material, characterized in that: It includes gel material, complexing agent, active chemical material and catalytic solvent, wherein the mass of the complexing agent is 40% of the mass of the gel material, the mass of the active chemical material is 60% of the mass of the gel material, and the mass of the catalytic solvent is 40-50% of the total mass of the gel material, the complexing agent and the active chemical material.

2. A self-repairable cement-based material according to claim 1, characterized in that: The gel material is cement.

3. The self-repairable cement-based material according to claim 1, characterized in that: The complexing agent is an amino acid complexing agent.

4. The self-repairable cement-based material according to claim 3, characterized in that: The complexing agent is ethylenediaminetetraacetic acid.

5. The self-repairable cement-based material according to claim 1, characterized in that: The active chemical material comprises a primary active chemical material and a secondary active chemical material, wherein the primary active chemical material comprises a soluble carbonate and an insoluble carbonate, and the secondary active chemical material comprises a soluble silicate.

6. The self-repairable cement-based material according to claim 5, characterized in that: The soluble carbonate includes sodium carbonate, the insoluble carbonate includes calcium carbonate, and the soluble silicate includes sodium silicate.

7. The self-repairable cement-based material according to claim 6, characterized in that: The mass ratio of the sodium carbonate, calcium carbonate and sodium silicate is 1:1:

1.

8. The self-repairable cement-based material according to claim 1, characterized in that: The catalyst is pure water.

9. A self-repairable cement-based material as claimed in any one of claims 1 to 8, applied to fire prevention and extinguishing in goaf areas of mines.

Images