Concrete self-repairing fine aggregate and its preparation method and application

Abstract

The present application provides concrete self-repairing fine aggregate and its preparation method and application. The concrete self-repairing fine aggregate includes floating beads and a repair agent. The floating beads are in the shape of porous hollow spheres. The repair agent is carried in the cavity of the floating beads, and the coating agent is dehydrated and conjunctivae on the outer shell of the floating beads. The concrete self-repairing fine aggregate provided by the present application uses floating beads as carriers of the repair agent. The floating beads themselves are hollow spheres. The cavity of the floating beads is used to store the repair agent. The coating agent is used to seal the holes in the outer shell of the floating beads to prevent the repair agent from overflowing. During use, when the concrete structure cracks, the stress generated by the cracking will destroy the wall shell of the floating beads, thereby releasing the repair agent in the cavity to repair the cracks and achieve the purpose of self-repair.

Description

Technical Field

[0001] The present application belongs to the technical field of building materials, and more specifically, relates to concrete self-repairing fine aggregate and its preparation method and application. Background Art

[0002] Due to climate change and other factors, irregular cracks may appear in building walls or roofs. As these cracks extend and expand, the building will age and deteriorate faster, and in severe cases, may even collapse. To prevent cracks in building walls or roofs from expanding and damaging the building, and to extend the building's service life, new cracks must be repaired promptly to prevent further deterioration and waterproofing.

[0003] The existing method for repairing cracks in concrete buildings involves adding self-healing materials to the concrete. These materials often use artificially prepared aggregates as a carrier for the repair agent. Currently, porous ceramics or sponges are commonly used as carriers for the repair agent. Porous ceramics are hard and resistant to damage, hindering the release of the repair agent. Sponges are soft and can be squeezed out with even the slightest external force. This can lead to the complete depletion of the repair agent before cracks appear in the building, making repair impossible. Summary of the Invention

[0004] Based on this, the present application provides concrete self-repairing fine aggregate and its preparation method and application, in order to solve the technical problem in the prior art that the carriers used in the currently commonly used fine aggregates are porous ceramics or sponges and other adsorbent repair agents, but these carriers have poor storage effects and are not conducive to the release of repair agents.

[0005] To achieve the above objectives, the technical solution adopted in this application is:

[0006] In a first aspect, a concrete self-repairing fine aggregate is provided, comprising floating beads and a repairing agent, wherein the floating beads are in the shape of porous hollow spheres, and the repairing agent is carried in the cavity of the floating beads.

[0007] Optionally, the repairing agent is sodium silicate; and / or,

[0008] The mass ratio of floating beads to repair agent is 1:2.5-4.

[0009] Optionally, the concrete self-repairing fine aggregate further includes a coating agent, which is coated on the outer surface of the floating beads.

[0010] Optionally, the coating agent comprises lithium silicate and / or silicon dioxide; and / or,

[0011] The mass ratio of the total mass of the floating beads and the repair agent to the mass ratio of the coating agent is 10-15:1.

[0012] Optionally, the pores contained in the wall of the floating beads have a pore size of 10-50 μm, and each 100 grams of floating beads can accommodate 90g-130g of repair agent.

[0013] In a second aspect, a method for preparing the above-mentioned concrete self-repairing fine aggregate is provided, comprising the following steps:

[0014] Providing floating beads, which are porous hollow spheres;

[0015] The repair agent solution is adsorbed in the cavity of the floating beads and dried, and the repair agent forms a solid and is carried on the cavity wall of the floating beads to obtain concrete self-repairing fine aggregate.

[0016] Optionally, the preparation method further comprises pre-treating the floating beads, wherein the pre-treatment comprises:

[0017] Initial floating beads are provided, and the initial floating beads are etched with a hydrofluoric acid solution to form holes on the surface of the initial floating beads, and the holes are connected to the cavity to obtain floating beads.

[0018] Optionally, the method of adsorbing the repair agent solution into the cavity of the floating beads comprises the following steps:

[0019] Immersing the beads in a repair agent solution, and adsorbing the repair agent solution into the cavity of the beads under vacuum conditions; and / or,

[0020] After the repair agent solution is adsorbed into the cavity of the floating beads, the following steps are also included:

[0021] The coating agent is coated on the outer surface of the floating beads to form a coating layer, thereby obtaining concrete self-repairing fine aggregate.

[0022] Optionally, the repair agent solution is a sodium silicate solution with a concentration of 19.9 mol / L-21.3 mol / L and a modulus of 2.1-2.5, and the repair agent solution is saturatedly adsorbed in the cavity of the floating beads; and / or,

[0023] The mass ratio of the total mass of the floating beads and the repairing agent to the mass of the coating agent is (10-15): (1-1.5).

[0024] A third aspect provides an application of the self-repairing fine aggregate for concrete in construction.

[0025] The beneficial effects of this application are:

[0026] 1. The concrete self-repairing fine aggregate provided by the present application uses floating beads as carriers of repair agents. The floating beads themselves are hollow spheres, and the cavity of the floating beads is used to store the repair agent. During use, when the concrete structure cracks, the stress generated by the cracks will destroy the shell of the floating beads, and then release the repair agent in the cavity to repair the cracks, thereby achieving the purpose of self-repair. Compared with the prior art, on the one hand, the concrete self-repairing fine aggregate used in the embodiment of the present application has a cavity structure with a good storage effect, and the shell of the floating beads has an appropriate hardness. Slight squeezing will not release the repair agent, while the stress of the building cracking can destroy the shell of the floating beads, release the repair agent, and then repair the cracks in the building. On the other hand, the floating beads used in the embodiment of the present application are floating beads in fly ash, which is a solid waste associated with thermal power generation. No additional manufacturing is required, which reduces the production process and production cost, has the advantage of low cost, and can also achieve the effect of energy saving and emission reduction.

[0027] 2. The preparation method of concrete self-repairing fine aggregate provided in the present application uses floating beads as a carrier. According to the structural characteristics of the floating beads, the repair agent is adsorbed in the cavity of the floating beads. Compared with the existing technology, traditional porous ceramics require additional manufacturing, which increases the manufacturing process and manufacturing costs. The floating beads in the present application are floating beads in fly ash, which are solid waste associated with thermal power generation. The floating beads do not require additional manufacturing, which reduces the manufacturing process and manufacturing costs. They are highly operational and suitable for large-scale industrial promotion.

[0028] 3. The concrete self-repairing fine aggregate provided in this application is applied to concrete structures, so that the concrete structures have stronger crack repair ability, mechanical property recovery ability and durability recovery ability after cracking. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The present invention will be further described below with reference to the accompanying drawings and embodiments, in which:

[0030] Figure 1 Schematic diagram of the process for preparing the concrete self-repairing fine aggregate according to Example 1 of the present application;

[0031] Figure 2 (a) is a scanning electron microscope image of the floating beads before pickling in Example 1 of the present application; Figure 2 (b) is a scanning electron microscope image of the beads after acid washing in Example 1;

[0032] Figure 3 This is a scanning electron microscope image of the cross section of the floating beads after loading sodium silicate in Example 1 of the present application;

[0033] Figure 4 This is a scanning electron microscope image of the finished product of the self-repairing fine aggregate of concrete in Example 1 of the present application;

[0034] Figure 5This is a scanning electron microscope image of nano-silica powder-coated floating beads in the concrete self-repairing fine aggregate in Example 2 of this application;

[0035] Figure 6 This is an image of the concrete sample before the cracks are healed after the concrete self-repairing fine aggregate is applied to the concrete sample in Example 1 of this application;

[0036] Figure 7 This is an image of the cracks in a concrete specimen healed after being applied with the concrete self-repairing fine aggregate in Example 1 of this application. DETAILED DESCRIPTION

[0037] In order to make the technical problems, technical solutions and beneficial effects to be solved by this application more clearly understood, this application is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0038] An embodiment of the present application provides a self-repairing fine aggregate for concrete, comprising floating beads and a repairing agent. The floating beads are in the shape of porous hollow spheres, and the repairing agent is carried in the cavity of the floating beads.

[0039] The concrete self-repairing fine aggregate provided in the embodiment of the present application uses floating beads as the carrier of the repair agent. The floating beads themselves are hollow spheres, and the cavity of the floating beads is used to store the repair agent. During use, when the concrete structure cracks, the stress generated by the cracking will destroy the wall shell of the floating beads, and then release the repair agent in the cavity to repair the cracks, thereby achieving the purpose of self-repair.

[0040] Compared with the existing technology, on the one hand, the floating beads used in the concrete self-repairing fine aggregate of the embodiment of the present application have a cavity structure, which has a good storage effect, and the wall hardness of the floating beads is appropriate. Slight squeezing will not release the repair agent, and the stress of the cracking of the building can destroy the wall of the floating beads, release the repair agent, and then repair the cracks in the building.

[0041] On the other hand, the floating beads used in the embodiment of the present application are floating beads in fly ash, which is a solid waste associated with thermal power generation. They do not require additional manufacturing, which reduces the production process and production costs. They have the advantage of low cost and can also achieve the effect of energy conservation and emission reduction.

[0042] Compared with traditional concrete structures, the concrete structure to which the concrete self-repairing fine aggregate of the embodiment of the present application is added will have stronger crack repair ability, mechanical property recovery ability and durability recovery ability after cracking.

[0043] The chemical composition of the floating beads is mainly silicon dioxide and aluminum oxide. The concrete self-repairing fine aggregate of the embodiment of the present application can be used as an auxiliary material such as fine aggregate to participate in the production of concrete, and can be used in the construction of houses or other buildings, and can improve the mechanical properties of concrete structures to a certain extent.

[0044] Existing self-repairing fine aggregates use wall materials as repair agents, such as high molecular organic polymers and bacteria that can generate mineral precipitation. Using these wall materials as repair agents has the following shortcomings:

[0045] Existing self-repairing fine aggregates are mostly made of high-molecular organic polymers. This directly leads to the problem of weak interfacial bonding between the self-repairing fine aggregate and the concrete matrix, thereby affecting the mechanical triggering efficiency of the self-repairing fine aggregate and greatly affecting the strength and stability of the concrete structure.

[0046] Using bacteria that produce mineral deposits as a self-repair mechanism for concrete can be slow to respond to defects like cracks, making it difficult to effectively control them immediately. Furthermore, given the impact of environmental factors like the high pH inside concrete, issues like bacterial activity remain to be addressed.

[0047] Therefore, in some optimized embodiments, the repair agent of the present invention includes water-activated mineral salts, which react with alkali in concrete to form water-insoluble compounds. After the beads are split, in the presence of moisture, the water-activated mineral salts react with mineral alkalis in the concrete, such as calcium hydroxide, to form water-insoluble compounds, enabling rapid self-healing of the cracks with excellent repair stability.

[0048] Water-active mineral salts may include, for example, sodium silicate. Sodium silicate can react with calcium hydroxide generated by hydration in concrete to generate a large amount of gel-state calcium silicate hydrate (i.e., CSH gel), which can seal and repair cracks in concrete and improve the mechanical strength of cracked concrete, thereby achieving the purpose of self-healing of concrete. The repair reaction equation is as follows:

[0049] Na2SiO3+Ca(OH)2+H2O→x(Ca.SiO3)H2O+NaOH.

[0050] Optionally, the mass ratio of the floating beads to the repair agent is 1:2.5-4. According to the pore capacity of the floating beads, the floating beads can accommodate the repair agent in this mass ratio and ensure that there is a sufficient amount of repair agent to play a good repair role.

[0051] Optionally, each 100g of beads can hold 90g-150g of the repair agent. After pickling, the pores in the bead wall have a diameter of 10-50μm, which can absorb the repair agent solution into the cavity of the beads by adsorption, and after drying, the repair agent is unlikely to leak out of the cavity.

[0052] In some embodiments, the concrete self-repairing fine aggregate also includes a coating agent, which is coated on the outer surface of the floating beads to seal the holes in the wall shell of the floating beads, store the repair agent in the cavity of the floating beads, reduce the loss of the repair agent during the concrete mixing process, and solve the problem of the floating beads being difficult to effectively store the repair agent when mixing with the cement matrix after absorbing the repair agent, and the problem of the floating beads sticking together and being difficult to separate after absorbing the repair agent.

[0053] The coating agent may include, for example, lithium silicate and / or silicon dioxide. In some embodiments, the coating agent may be lithium silicate alone, silicon dioxide alone, or a mixture of lithium silicate and silicon dioxide. When the coating agent is lithium silicate, during the preparation process, a lithium silicate solution is used to coat the outer surface of the floating beads. After drying, the lithium silicate forms a water-insoluble crystalline film on the outer surface of the floating beads, which can block the pores on the surface of the floating beads and protect the adsorbent adsorbed inside the floating beads.

[0054] When the coating agent is silica, during the preparation process, because water-active mineral salts such as sodium silicate crystals will increase in viscosity when heated, and because the particle size of nano-silica powder is much smaller than the size of the pores of the beads, it can adhere to the outer surface of the beads during the heating and stirring process, continuously blocking the pores, thereby achieving the purpose of isolating the cavity to protect the repair agent.

[0055] When the coating agent includes silica, silica can also react with calcium hydroxide in concrete to form CSH gel. This reaction can increase the bonding stress between the outer shell of the beads and the cement matrix, allowing the beads to be stored more stably in the concrete. The reaction equation is as follows:

[0056]

[0057] Ca(OH)2+H2O→Ca 2+ +OH - , (b)

[0058]

[0059] Optionally, the mass ratio of the total mass of the floating beads and the repairing agent to the mass ratio of the coating agent is (10-15): (1-1.5), that is, after the repairing agent is carried on the floating beads, the mass ratio of the total mass of the two to the coating agent is (10-15): (1-1.5). The main function of the coating agent is to block the holes on the wall of the floating beads cavity. It can be understood that the more coating agents there are, the stricter the holes are blocked. However, if the blocking is too strict, it will affect the effect of subsequent concrete self-repair of fine aggregate cracking and releasing the repairing agent. Therefore, the thickness of the coating agent does not need to be too thick. It only coats one or two layers of coating layers to achieve no or little loss of the repairing agent when mixed with the cement matrix. When the concrete structure cracks, the coating layer and the floating beads can be torn, so that moisture contacts the repairing agent in the floating bead cavity and reacts. Therefore, the amount of coating agent used in the embodiment of the present application is selected to be the mass ratio of the total mass of the floating beads and the repairing agent to the coating agent of (10-15): (1-1.5).

[0060] The present application also provides a method for preparing the above-mentioned concrete self-repairing fine aggregate, comprising the following steps:

[0061] S1: Provide porous hollow spherical floating beads.

[0062] Floating beads are hollow balls of fly ash that can float on the water surface. Generally, the floating beads are thin-walled, enclosed hollow spherical structures, or there are pinholes on the thin walls of the floating beads, which make it difficult to adsorb the repair agent or the efficiency of adsorbing the repair agent is very low. Therefore, the floating beads need to be pre-treated before adsorbing the repair agent to form holes on the surface of the floating beads, and the holes are connected to the cavity so that the repair agent can flow into the cavity through the holes.

[0063] In some embodiments, the pre-treatment method of floating beads includes:

[0064] Initial floating beads are provided, and the initial floating beads are etched with a hydrofluoric acid solution to form holes on the surface of the initial floating beads, and the holes are connected to the cavity to obtain floating beads.

[0065] The surface of the initial floating beads has a vitrified layer. By pickling with hydrofluoric acid solution, part of the vitrified layer can be removed to form holes connected to the cavity, greatly improving the solution adsorption rate and the release rate of the repair agent after the floating beads are damaged.

[0066] Optionally, the etching method includes:

[0067] The initial floating beads are placed in a container filled with hydrofluoric acid solution, and the surfaces of the initial floating beads are fully contacted with the hydrofluoric acid solution under stirring.

[0068] In some embodiments, the concentration of the hydrofluoric acid solution is 1 mol / L-1.5 mol / L, and the relationship between the amount of the hydrofluoric acid solution and the amount of the initial floating beads is: 1 L of hydrofluoric acid solution can treat 200 g-300 g of the initial floating beads.

[0069] After the etching process is complete, the beads are rinsed and then dried at 100-110°C to obtain the beads. In some embodiments, after drying, the beads are sieved to <20 mesh, 20-30 mesh, and 30-60 mesh, and beads of corresponding mesh sizes are selected as needed. In some embodiments, beads of 20-30 mesh are selected for use. This mesh size can store a sufficient amount of repair agent and, when added to concrete as an auxiliary material, does not affect the concrete's buildability.

[0070] S2: The repair agent solution is adsorbed into the cavity of the floating beads and dried. The repair agent forms a solid and is carried on the cavity wall of the floating beads to obtain concrete self-repairing fine aggregate.

[0071] Optionally, the method of adsorbing the repair agent solution into the cavity of the floating beads comprises the following steps:

[0072] The floating beads are immersed in the repair agent solution, and under vacuum conditions, the repair agent solution is adsorbed into the cavity of the floating beads.

[0073] In some embodiments, the method of adsorbing the repair agent solution into the cavity of the floating beads includes:

[0074] Providing a first reaction container, the first reaction container having a vacuum port and an exhaust port, the vacuum port is used to connect to a vacuum pump, and the exhaust port is used for exhausting;

[0075] The floating beads are placed in a first reaction container, the first reaction container is evacuated for the first time using a vacuum pump, and then the floating beads are evacuated under negative pressure;

[0076] After the negative pressure exhaust is completed, the exhaust valve is opened, and the repair agent solution is sucked into the first reaction container through a catheter, and the liquid surface of the repair agent solution is made to cover the surface of the floating beads. Then the exhaust valve is closed, and the first reaction container is vacuumed for the second time through a vacuum pump, so that the floating beads negatively absorb the repair agent solution to obtain concrete self-repairing fine aggregate.

[0077] First, vacuum exhaust the floating beads to expel the trace moisture in their cavity, which can effectively increase the adsorption rate of the repair agent. Then, vacuum negative pressure adsorption of the repair agent solution is performed to allow it to fully enter the cavity of the floating beads.

[0078] It is understandable that in addition to the vacuum adsorption method, different adsorption treatment methods can also be selected according to the characteristics of the repair agent.

[0079] Optionally, the repair agent solution is a sodium silicate solution with a modulus of 2.1-2.5 and a concentration of 19.9 mol / L-21.3 mol / L.

[0080] In some embodiments, the concrete self-repairing fine aggregate needs to be coated with a waterproof membrane. After the repair agent solution is adsorbed into the cavity of the floating beads, the method further includes:

[0081] The coating agent is coated on the outer surface of the floating beads to form a coating layer, thereby obtaining concrete self-repairing fine aggregate.

[0082] The coating agent can be liquid or solid. When the coating agent is liquid, such as lithium silicate solution, the coating agent can be adsorbed on the surface of the floating beads by spraying, and the coating agent liquid can be sprayed on the surface of the floating beads to form a coating agent layer on the surface of the floating beads.

[0083] In some embodiments, the method of adsorbing the coating agent on the surface of the floating beads includes:

[0084] Add floating beads to a drum granulator, maintain a speed of 60r / min, and continuously apply 60°C hot air. After drying for 2-3 hours, spray a lithium silicate solution with a concentration of 1.5mol / L and a modulus of 4-5 at a certain frequency to form a well-coated waterproof protective film on the surface of the floating beads. The principle is that the lithium silicate solution forms a water-insoluble crystalline film after drying, which can block the pores on the surface of the floating beads and protect the repair agent adsorbed inside the beads.

[0085] When the coating agent is solid, such as nano-silica powder, the method of coating the coating agent on the outer surface of the floating beads includes:

[0086] The intermediate product obtained in step S2 and the nano-silica powder are placed in a third reaction container, heated in a water bath and fully stirred to allow them to be fully mixed to seal the holes of the floating beads and protect the repair agent.

[0087] The water-active mineral salts in the repair agent, such as sodium silicate, will increase their viscosity when heated. Since the particle size of nano-silica powder is smaller than the pore size of the floating beads, it can continuously adhere to the surface of the floating beads and seal the pores during the heating and stirring process, thereby isolating the cavity to protect the repair agent.

[0088] The method for preparing the self-repairing fine aggregate for concrete provided in the embodiments of the present application uses floating beads as a carrier. Based on the structural characteristics of the floating beads, the repair agent is adsorbed into the cavity of the floating beads. The floating beads do not require additional manufacturing, which reduces the production process and manufacturing costs. This solves the problem of the complex preparation process of self-repairing wall materials and can directly use existing fly ash floating beads as a carrier for the repair agent. At the same time, the self-repairing fine aggregate for concrete can also be used as an auxiliary material, such as fine aggregate to replace part of natural sand or cement ash and added to concrete materials for building construction. The method for preparing the self-repairing fine aggregate for concrete provided in the embodiments of the present application is highly operational and suitable for large-scale industrial promotion.

[0089] The following is illustrated by multiple embodiments.

[0090] Example 1

[0091] The preparation method of the concrete self-repairing fine aggregate of this embodiment is as follows Figure 1 As shown, the following steps are included:

[0092] S1: Take 200g of initial floating beads. Figure 2 (a) in the stirring state, 1L1.2mol.L -1 The initial floating beads were acid washed with hydrofluoric acid solution for 2 hours.

[0093] S2: After the pickling is completed, rinse and rinse for 7-8 times, and then dry at 105 ° C for 24 hours to obtain floating beads. The scanning electron microscope image of the floating beads is shown in Figure 2 (b) in the.

[0094] S3: Take the dried floating beads and place them in the first reaction container. Then, vent the first reaction container under negative pressure and keep the container under 0.1 MPa vacuum pressure for 30 minutes. Then, add 500 g, 20 mol.L -1 , a sodium silicate solution with a modulus of 2.1-2.5, until the sodium silicate solution submerges the surface of the floating beads, and then negative pressure adsorption is carried out for 120 minutes at the same vacuum pressure to obtain the first primary product, the internal morphology of which is shown in FIG. Figure 3 .

[0095] S4: Take out the adsorbed product and wash it with water three times. After draining the surface water, place it in a drum granulator for rolling drying. Keep the drum speed at 60r / min under the blowing of hot air at 60℃ for 3 hours.

[0096] After the sodium silicate inside the beads is shaped, 1.5 mol / L lithium silicate solution with a modulus of 4.5 is sprayed. The spraying mass is 1 / 10-1 / 15 of the mass of the beads (including the repair agent). At the same time, 60°C hot air is continuously applied to form a well-coated waterproof protective film on the surface of the beads to obtain concrete self-repairing fine aggregate. Its morphology is shown in the figure. Figure 4 shown.

[0097] The preparation of self-repairing concrete includes the following steps:

[0098] 100 g of cement, 291 g of standard sand and 9 g of the self-repairing fine aggregate prepared in Example 1 were added to a mixer and the stirring blade speed was maintained at 100 r / min and stirred for 3 minutes. At the same time, 50 g of mixing water was added at a uniform rate during the stirring process, and then stirred for 3 minutes at 150 r / min to obtain a mixture. After the mixture was cast and demolded, it was subjected to standard curing for 28 days at 20±2°C and 95% RH to obtain self-repairing concrete.

[0099] Example 2

[0100] The method for preparing the concrete self-repairing fine aggregate of this embodiment differs from that of Example 1 in that the coating agent of this embodiment is nano-silicon dioxide powder, and step S4 is changed to:

[0101] Place the second primary product in a water bath and heat it to 80-85°C for more than 3 minutes. Then add nano-silica powder at a mass ratio of 1:2 to the second primary product. Continue stirring for more than 5 minutes until most of the floating beads are evenly coated with nano-silica powder. Then place it in a drying oven at 60°C for 24 hours to obtain concrete self-repairing fine aggregate. The effect of nano-silica powder coating floating beads is shown in the figure below. Figure 5 shown.

[0102] Example 3

[0103] The method for preparing the self-repairing fine aggregate of concrete in this embodiment differs from that in Example 1 in that the mass ratio of the floating beads to the repairing agent in this embodiment is 1:3, and step S3 is changed to:

[0104] S3: Take the dried floating beads and place them in the first reaction container. Negative pressure exhaust is applied to the first reaction container for 30 minutes. Then, 600g, 20mol.L -1 , a sodium silicate solution with a modulus of 2.1-2.5, until the sodium silicate solution submerges the surface of the floating beads, and then negative pressure adsorption is performed for 30 minutes to obtain the first primary product.

[0105] Example 4

[0106] The method for preparing the self-repairing fine aggregate of concrete in this embodiment differs from that in Example 1 in that the mass ratio of the floating beads to the repairing agent in this embodiment is 1:3.5, and step S3 is changed to:

[0107] S3: Take the dried floating beads and place them in the first reaction container. Then, vent the first reaction container under negative pressure for 30 minutes and add 700g, 20mol.L -1 , a sodium silicate solution with a modulus of 2.1-2.5, until the sodium silicate solution submerges the surface of the floating beads, and then negative pressure adsorption is performed for 30 minutes to obtain the first primary product.

[0108] The relationship between the crack healing effect (percentage), the repair days, and the crack width after the concrete self-repairing fine aggregate of Example 1 was applied to the concrete structure is shown in Table 1.

[0109] Table 1

[0110]

[0111] It can be seen that the concrete self-repairing fine aggregate prepared by the preparation method of the present application can be used in concrete structures to quickly repair cracks with good repair effects, especially when the crack width is less than 100 μm, it can be repaired 100% in 7 days.

[0112] The concrete self-repairing fine aggregate of Example 1 is applied to the water-cured repair effect of cracked concrete structure as shown in the figure below. Figure 6 shown.

[0113] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. Application of a concrete self-repairing fine aggregate in building concrete, characterized by: The concrete self-repairing fine aggregate includes floating beads and a repairing agent, wherein the floating beads are in the shape of porous hollow spheres, and the repairing agent is carried in the cavity of the floating beads; The repair agent includes sodium silicate; The mass ratio of the floating beads to the repair agent is 1:2.5-4; The concrete self-repairing fine aggregate further includes a coating agent, which is coated on the outer surface of the floating beads; The coating agent includes lithium silicate and / or silicon dioxide.

2. The use of the self-repairing fine aggregate for concrete in construction concrete according to claim 1, characterized in that: The pores contained in the wall of the floating beads have a pore size of 10-50 μm, and every 100 grams of the floating beads can accommodate 90g-150g of the repair agent.

3. The use of the self-repairing fine aggregate for concrete in construction concrete according to claim 1, characterized in that: The method for preparing the concrete self-repairing fine aggregate comprises the following steps: Providing floating beads, wherein the floating beads are in the shape of porous hollow spheres; The repair agent solution is adsorbed in the cavity of the floating beads and dried, and the repair agent forms a solid and is carried in the cavity of the floating beads to obtain concrete self-repairing fine aggregate.

4. The use of the self-repairing fine aggregate for concrete in construction concrete according to claim 2, characterized in that: The preparation method further includes pre-treating the floating beads, and the pre-treatment includes: Initial floating beads are provided, and the initial floating beads are etched with a hydrofluoric acid solution to form holes on the surface of the initial floating beads, and the holes are connected to the cavity to obtain the floating beads.

5. The use of the self-repairing fine aggregate for concrete in construction concrete according to claim 2, characterized in that: The method for adsorbing the repair agent solution into the cavity of the floating beads comprises the following steps: Immersing the floating beads in the repair agent solution, and adsorbing the repair agent solution into the cavity of the floating beads under vacuum conditions; and / or, After the repair agent solution is adsorbed into the cavity of the floating beads, the method further comprises: The coating agent is coated on the outer surface of the floating beads to form a coating layer, thereby obtaining the concrete self-repairing fine aggregate.

6. The use of the self-repairing fine aggregate for concrete in construction concrete according to claim 4, characterized in that: The repair agent solution is a sodium silicate solution with a concentration of 19.9 mol / L-21.3 mol / L and a modulus of 2.1-2.5, and the repair agent solution is saturatedly adsorbed in the cavity of the floating beads; and / or, The mass ratio of the total mass of the floating beads and the repair agent to the mass of the coating agent is (10-15): (1-1.5).

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