An air-driven repair material for concrete cracks and its usage method

Abstract

The present invention discloses a gas-driven repair material for concrete cracks and its usage method. The gas-driven repair material for concrete cracks includes: 120-500 parts by weight of portland cement, 95-380 parts by weight of gas-driven repair particles, 72-356 parts by weight of sand, 30-90 parts by weight of steel slag powder, 20-58 parts by weight of aluminum sulfate powder, 12-30 parts by weight of fiber, and 200-440 parts by weight of mixing water. The usage method includes the steps: (i) Mix the raw materials evenly to obtain the gas-driven repair material. (ii) Inject the gas-driven repair material into the cracks of the concrete structure, then perform microwave heating treatment on the gas-driven repair material, and after completion, perform natural curing. The present invention utilizes the gas drive to make the repair material enter the deep part of the cracks more fully, and helps to activate the crack surface, improve the bonding force with the repair material, and enhance the repair effect on concrete cracks.

Description

Technical Field

[0001] The present invention relates to the technical field of concrete crack repair, and particularly to a gas-driven repair material for concrete cracks and a method for using the same. Background Art

[0002] Disclosing the information of this background art section is only intended to enhance the overall understanding of the present invention, and is not necessarily to be regarded as an admission or any form of implication that this information constitutes prior art already known to those of ordinary skill in the art.

[0003] Concrete is a heterogeneous brittle material formed by mixing sand and gravel aggregates, cement, water and other additional materials. Although concrete has good compressive strength, due to its low tensile strength, it often cracks during the later service process. Concrete cracks have become the most common engineering diseases in many projects. After cracks occur in the concrete structure, the internal reinforcement materials such as steel bars are more likely to rust when exposed, and at the same time, these cracks also lead to a decrease in the bearing capacity of the concrete structure, accelerate the aging of the concrete structure due to water penetration, reduce durability, and affect the safety of the concrete structure. When the cracks are severe, brittle failure is likely to occur, leading to safety accidents.

[0004] However, as an inert material that has been cured, once cracks appear in the concrete structure, it is not only difficult and costly to repair, but also the repair effect is not easily achieved as expected. Therefore, how to improve the repair effect of cracks has become an important problem faced by the later maintenance of concrete structures. At present, the common method for repairing concrete cracks is to apply concrete mortar to the cracks to form a filling, and after the concrete mortar hardens, it combines with the cracks to achieve repair. However, this method generally has problems such as the inability of the concrete mortar to fully enter the deep part of the cracks and the insufficient bonding force between the concrete mortar and the crack surface, and the latter is likely to cause the repaired concrete mortar in the cracks to fall off again later. Summary of the Invention

[0005] The present invention provides a gas-driven repair material for concrete cracks and a method for using the same, which uses gas drive to promote the repair material to enter the deep part of the cracks more fully and helps to activate the crack surface, improve the bonding force between it and the repair material, thereby enhancing the repair effect on concrete cracks. Specifically, the technical solutions of the present invention are as follows.

[0006] First, the present invention discloses a gas-driven repair material for concrete cracks, and its raw material composition includes: 120-500 parts by weight of portland cement, 95-380 parts by weight of gas-driven repair particles, 72-356 parts by weight of sand, 30-90 parts by weight of steel slag powder, 20-58 parts by weight of aluminum sulfate powder, 12-30 parts by weight of fiber, 200-440 parts by weight of mixing water, and 5-20 parts by weight of water reducing agent. Among them: The gas-driven repair particles are prepared by the following method:

[0007] (1) Place ferrosilicon slag in sulfuric acid for acid leaching treatment. After completion, separate the solid product to obtain modified ferrosilicon slag I, and at the same time collect the separated liquid phase for later use.

[0008] (2) Add an alkaline substance to the liquid phase to neutralize the residual sulfuric acid, then add sodium borohydride (NaBH4) and perform ultrasonic treatment simultaneously. After the precipitation of the precipitate ends, separate the solid product and collect the separated liquid. Vacuum dry the solid product to obtain metal micropowder. Add sulfuric acid to the separated liquid to eliminate the residual sodium borohydride to obtain the mixing water for later use.

[0009] (3) Mix tetraethoxysilane liquid, bicarbonate powder and the metal micropowder and disperse them ultrasonically to form a suspension mixture. Then immerse the modified ferrosilicon slag I in this suspension mixture for ultrasonic treatment. After completion, let it stand, and then separate the modified ferrosilicon slag I, which is modified ferrosilicon slag II.

[0010] (4) Form a coating liquid from molten paraffin liquid and graphene. Immerse the modified ferrosilicon slag II in this coating liquid for coating, and then take out the modified ferrosilicon slag II. After cooling, a coating layer is formed on its surface to obtain the gas-driven repair particles.

[0011] Further, in step (1), the material-liquid ratio of the ferrosilicon slag to sulfuric acid is 1g: 20-30ml. Optionally, the mass fraction of the sulfuric acid is 20-35%. The time for the acid leaching treatment is 1-1.5h. The particle size of the ferrosilicon slag is between 1-3mm.

[0012] Further, in step (2), the alkaline substance includes at least one of sodium hydroxide, sodium carbonate, sodium bicarbonate, etc.

[0013] Further, in step (2), the mass fraction of sodium borohydride in the system is 7-11%. Optionally, the time for the ultrasonic treatment is 20-25min, and the ultrasonic power is 300-500W.

[0014] Further, in step (2), the drying temperature is 80-95°C and the time is 40-55min.

[0015] Further, in step (3), the ratio of the tetraethoxysilane liquid, the bicarbonate powder, and the metal micropowder is 1 L: 1-2 g: 5-8 g. Optionally, the time for ultrasonic dispersion is 10-15 min, and the ultrasonic power is 300-500 W.

[0016] Further, in step (3), the bicarbonate includes at least one of sodium bicarbonate, calcium bicarbonate, and magnesium bicarbonate.

[0017] Further, in step (3), the ratio of the modified ferrosilicon slag I to the suspension material is 1 g: 30-40 ml.

[0018] Further, in step (3), the time for ultrasonic treatment is 5-10 min, the ultrasonic power is 200-300 W, and the standing time is 10-20 min.

[0019] Further, in step (4), the ratio of the molten paraffin liquid to the graphene is 10 parts by weight: 0.8-1.5 parts by weight.

[0020] Further, in step (4), the thickness of the coating layer is controlled to be below 0.5 mm.

[0021] Further, the fiber includes any one of glass fiber, carbon fiber, etc. Optionally, the length of the fiber is 5-10 mm.

[0022] Secondly, the present invention discloses a method for using the gas-driven repair material for concrete cracks, including the steps:

[0023] (i) Mix the raw material components of the gas-driven repair material for concrete cracks evenly to obtain the gas-driven repair material for standby.

[0024] (ii) Inject the gas-driven repair material into the cracks of the concrete structure, and then perform microwave heating treatment on the gas-driven repair material, and natural curing can be carried out after completion.

[0025] Further, the microwave heating frequency is 5-20 GHz, the power is 600-1000 W, and the heating time is 30-150 s.

[0026] Compared with the prior art, the present invention has at least the following beneficial technical effects:

[0027] As described above, the traditional method of filling and repairing cracks in concrete structures with cement mortar has problems such as poor repair effect. The present invention proposes a technical solution to promote the movement of the repair material deep into the crack by means of air drive, effectively improving the repair effect. For this purpose, the present invention first uses porous ferrosilicon slag containing rich metal elements such as iron, aluminum, and magnesium as raw materials, and dissolves these metal elements after acid leaching treatment. On the one hand, it can effectively expand the pores of the ferrosilicon slag to facilitate the entry of the suspension mixture. On the other hand, it is convenient to use the dissolved metal elements to prepare the metal micropowder for absorbing microwave heat. Further, the present invention adds an alkaline substance to the system after acid leaching treatment to convert the excess sulfuric acid into sodium sulfate. After adding the sodium borohydride, the dissolved metal elements are reduced to form metal micropowders and precipitate. After the present invention loads the suspension mixture formed by these metal micropowders, tetraethoxysilane liquid and bicarbonate powder into the ferrosilicon slag, a coating layer formed by molten paraffin and graphene is further used to encapsulate the suspension mixture into the ferrosilicon slag to form air-driven repair particles. When it and the repair material are filled into the cracks of the concrete structure and heated with microwaves, the graphene in the coating layer absorbs microwave heat and melts the coating layer. At the same time, the metal micropowders in the ferrosilicon slag also absorb microwave heat to heat the bicarbonate powder, causing it to decompose and generate carbon dioxide to overflow outwards from the pores of the ferrosilicon slag, thereby driving the surrounding repair material to fill deep into the crack, enabling each part of the crack to be more fully filled with the repair material and achieving more precise repair. At the same time, the graphene released after the coating layer melts is dispersed and enters the deep part of the crack during the movement of the repair material. These graphene can effectively improve the mechanical properties and impermeability of the repair material. Since the crack is the key part where the concrete structure leaks, using the above method to improve the impermeability of the repaired part is very important for enhancing the repair effect. Further, during the hardening process of the repair material, the mixing water enters the ferrosilicon slag, and the tetraethoxysilane therein undergoes hydrolysis under the action of water and the heat provided by the hydration reaction to form silica microparticles that fill the pores of the ferrosilicon slag. These silica microparticles have high reactivity, and the cementitious material formed by their hydration reaction not only helps to improve the compactness of the ferrosilicon slag, thus preventing the problem of insufficient impermeability caused by the porous ferrosilicon slag in the repaired part. At the same time, the densified ferrosilicon slag has higher mechanical strength, which helps to improve the repair effect.

[0028] In addition, the separation liquid obtained in step (2) of the present invention is treated and used as the mixing water of the repair material. The separation liquid contains sodium sulfate formed after neutralizing the residual sulfuric acid and sodium borohydride added subsequently. After adding sulfuric acid again, the sodium borohydride reacts to form sodium sulfate and boric acid. Among them, the sodium sulfate, as an alkali activator, helps to improve the hydration activity of the steel slag powder and ferrosilicon slag, enabling the steel slag powder not only to play a filling role as a fine aggregate, but also to undergo a hydration reaction to form a cementitious material and better combine with the repair material matrix. At the same time, the ferrosilicon slag can also undergo a hydration reaction and better combine with the repair material matrix, thereby promoting the improvement of the strength of the repair material and enhancing the repair effect. At the same time, the boric acid plays a retarding role, which helps to provide more sufficient time for the repair material to flow in the crack, avoiding the rapid solidification of the repair material and resulting in insufficient time to fully fill the crack. In addition, during the hydration process of the repair material, the carbon dioxide reacts with the hydration product calcium hydroxide to form calcium carbonate, which fills in the repair material and helps to improve the compactness of the repair material. In addition, the aluminum sulfate in the repair material of the present invention can react with the hydration product calcium hydroxide of the original concrete on the crack surface to form calcium sulfate and aluminum hydroxide. The calcium sulfate further reacts with tricalcium aluminate in the Portland cement to form ettringite with slight expansion. Together with the aluminum hydroxide, they fill in the interface between the repair material and the crack surface, which helps to improve the impermeability of the interface. At the same time, by activating the crack surface to participate in the reaction in the above manner, the bonding force between the crack surface and the repair material is improved, which helps to reduce the occurrence of the repair material in the crack falling off during subsequent service and enhance the repair effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The specification drawings forming a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention.

[0030] Figure 1 It is the effect diagram of the gas-driven repair particles prepared in Example 1 of the present invention below.

[0031] Figure 2 It is the pre-crack effect diagram of the concrete test block prepared in Example 1 of the present invention below.

[0032] Figure 3 It is the effect diagram of the gas-driven repair particles prepared in Example 2 of the present invention below. DETAILED DESCRIPTION OF THE INVENTION

[0033] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. The experimental methods without specific conditions noted in the following embodiments are generally carried out under conventional conditions or according to the conditions recommended by the manufacturers. In addition, unless otherwise defined, all professional and scientific terms used in the present invention have the same meaning as those familiar to those skilled in the art.

[0034] The reagents or raw materials used in the present invention can all be obtained through conventional channels. Unless otherwise specified, the reagents or raw materials used in the present invention are used in the conventional manner in the art or according to the product instructions. In addition, any methods and materials similar or equivalent to the recorded content can be applied to the method of the present invention. The preferred implementation methods and materials described in the present invention are only for demonstration purposes.

[0035] The present invention will be further described in detail below in conjunction with the accompanying drawings of the specification and specific embodiments. It should be noted that the following embodiments and materials are only for demonstration purposes and do not limit the technical solutions of the present invention. For example, the ferrosilicon slag listed below is only an example, and it does not explicitly or implicitly limit the preparation of the air-driven repair material for concrete cracks of the present invention to the ferrosilicon slag with the following components.

[0036] In the following embodiments, the main components of the ferrosilicon slag used include: SiO2 52.7%, FeO 21.4%, Al2O3 13.2%, CaO 6.7%, MgO 4.1%, and the balance is TiO2, MnO, etc.

[0037] Example 1

[0038] A preparation method of an air-driven repair material for concrete cracks includes the following steps:

[0039] 1. Preparation of air-driven repair particles, including the following steps:

[0040] (1) Mix ferrosilicon slag with a particle size distribution between 1 and 2 mm and a sulfuric acid solution with a mass fraction of 30% in a ratio of 1 g:25 ml, stir evenly, and then let it stand for 1 h for acid leaching treatment. After that, add sodium carbonate to neutralize the residual sulfuric acid, and then filter out the solid product to obtain modified ferrosilicon slag I, and collect the filtrate for later use.

[0041] (2) Add sodium borohydride to the filtrate to form a liquid-phase reaction system with a mass fraction of 10%, and then ultrasonically treat the liquid-phase reaction system for 20 min with an ultrasonic power of 400 W. After the precipitation of the precipitated substances is completed, centrifuge to separate the solid product, and collect the supernatant of the centrifugation. Vacuum-dry the solid product at 90 °C for 45 min to obtain metal micropowder. Add sulfuric acid to the supernatant to eliminate the residual sodium borohydride to obtain mixing water for standby.

[0042] (3) Mix tetraethoxysilane liquid, sodium bicarbonate powder, and the metal micropowder prepared in this example in a ratio of 1 L: 1.5 g: 7 g, and ultrasonically disperse for 15 min (ultrasonic power is 350 W) to form a suspension mixture. Then mix the modified ferrosilicon slag I with the suspension mixture in a ratio of 1 g: 35 ml, ultrasonically treat for 10 min (ultrasonic power is 200 W), let it stand for 15 min after completion, and then separate the modified ferrosilicon slag I, denoted as modified ferrosilicon slag II.

[0043] (4) Mix molten paraffin liquid and graphene in a mass ratio of 10: 0.45 and ultrasonically disperse to form a coating liquid. Then immerse the modified ferrosilicon slag II in the coating liquid for coating, and then take out the modified ferrosilicon slag II. After cooling to room temperature, a coating layer with a thickness of 0.3 mm is formed on the surface of the modified ferrosilicon slag II to obtain the gas-driven repair particles (as Figure 1 shown).

[0044] 2. Prepare raw materials in the following weight ratio: 350 parts by weight of 42.5 Portland cement, 260 parts by weight of the gas-driven repair particles prepared in this example, 280 parts by weight of river sand, 40 parts by weight of steel slag powder, 24 parts by weight of aluminum sulfate powder, 20 parts by weight of chopped glass fibers with a length of 7 mm, 305 parts by weight of mixing water, and 11 parts by weight of polycarboxylate water reducer. Mix the above raw materials evenly to obtain the gas-driven repair material.

[0045] 3. Prepare a Portland cement concrete test block with dimensions of 150 mm × 150 mm × 150 mm, place it in a standard curing room at a temperature of 20 ± 2 °C and a relative humidity greater than 95% for 28 days, and use a press to test the ultimate compressive strength of the concrete test block. Then, according to 80% of the measured ultimate compressive strength, apply pressure to another concrete test block to obtain pre-cracked cracks (as Figure 2 shown). Then grout the gas-driven repair material prepared in this example into the cracks and perform microwave heating with a heating power of 800 W, a frequency of 10 GHz, and heat for 60 s. After completion, cure for 14 days in the same manner as above, and then test its compressive strength and capillary water absorption to reflect the crack repair effect. The results are: compressive strength = 51.76 MPa, capillary water absorption = 1.8 mm.

[0046] Example 2

[0047] A preparation method of a gas-driven repair material for concrete cracks, comprising the following steps:

[0048] 1. Preparation of gas-driven repair particles, comprising the following steps:

[0049] (1) Mix ferrosilicon slag with a particle size distribution between 1 and 3 mm and a 35% sulfuric acid solution in a ratio of 1 g: 20 ml, stir evenly, and let stand for 1.2 h for acid leaching treatment. After that, add sodium hydroxide to neutralize the residual sulfuric acid, and then filter out the solid product to obtain modified ferrosilicon slag I. At the same time, collect the filtrate for later use.

[0050] (2) Add sodium borohydride to the filtrate to form a liquid-phase reaction system with a mass fraction of 7%. Then, ultrasonically treat the liquid-phase reaction system for 20 min with an ultrasonic power of 500 W. After the precipitation ends, centrifuge to separate the solid product, and collect the supernatant of the centrifugation. Dry the solid product in vacuum at 80 °C for 55 min to obtain metal micropowder. Add sulfuric acid to the supernatant to eliminate the residual sodium borohydride to obtain mixing water for later use.

[0051] (3) Mix tetraethoxysilane liquid, calcium bicarbonate powder and the metal micropowder prepared in this example in a ratio of 1 L: 1.8 g: 8 g, and ultrasonically disperse for 10 min (ultrasonic power is 300 W) to form a suspension mixture. Then, mix the modified ferrosilicon slag I with the suspension mixture in a ratio of 1 g: 40 ml, ultrasonically treat for 10 min (ultrasonic power is 300 W), let stand for 20 min after completion, and then separate the modified ferrosilicon slag I, denoted as modified ferrosilicon slag II.

[0052] (4) Mix heated and melted paraffin liquid and graphene in a mass ratio of 10: 0.8, and ultrasonically disperse to form a coating liquid. Then, immerse the modified ferrosilicon slag II in the coating liquid for coating, and then take out the modified ferrosilicon slag II. After cooling to room temperature, a coating layer with a thickness of 0.5 mm is formed on the surface of the modified ferrosilicon slag II to obtain the gas-driven repair particles (as Figure 3 shown).

[0053] 2. Prepare raw materials in the following weight ratio: 120 parts by weight of 42.5 Portland cement, 95 parts by weight of the gas-driven repair particles prepared in this example, 72 parts by weight of river sand, 30 parts by weight of steel slag powder, 20 parts by weight of aluminum sulfate powder, 12 parts by weight of chopped glass fibers with a length of 5 mm, 200 parts by weight of mixing water, and 5 parts by weight of polycarboxylate water reducer. Mix the above raw materials evenly by stirring to obtain the gas-driven repair material.

[0054] 3. Test the compressive strength and capillary water absorption of the concrete specimens repaired with the gas-driven repair material prepared in this example in the same manner as in Example 1 above, except that the heating power of the microwave heating is 600 W, the frequency is 20 GHz, and the heating time is 30 s. The test results are as follows: compressive strength = 53.44 MPa, capillary water absorption = 2.5 mm.

[0055] Example 3

[0056] A preparation method of a gas-driven repair material for concrete cracks, comprising the following steps:

[0057] 1. Preparation of gas-driven repair particles, comprising the following steps:

[0058] (1) Mix ferrosilicon slag with a particle size distribution between 2 and 3 mm and a sulfuric acid solution with a mass fraction of 20% at a ratio of 1 g:25 ml, stir evenly, and then stand for 1.5 h for acid leaching treatment. After adding sodium carbonate to neutralize the residual sulfuric acid, filter out the solid product to obtain modified ferrosilicon slag I, and collect the filtrate for later use.

[0059] (2) Add sodium borohydride to the filtrate to form a liquid-phase reaction system with a mass fraction of 9%, and then ultrasonically treat the liquid-phase reaction system for 25 min with an ultrasonic power of 300 W. After the precipitation ends, centrifuge to separate the solid product, and collect the supernatant of the centrifugation. Dry the solid product in a vacuum at 95 °C for 40 min to obtain metal micropowder. Add sulfuric acid to the supernatant to eliminate the residual sodium borohydride to obtain mixing water for later use.

[0060] (3) Mix tetraethoxysilane liquid, magnesium bicarbonate powder and the metal micropowder prepared in this example at a ratio of 1 L:1 g:5 g, ultrasonically disperse for 12 min (ultrasonic power is 400 W) to form a suspension mixture. Then mix the modified ferrosilicon slag I with the suspension mixture at a ratio of 1 g:35 ml, ultrasonically treat for 10 min (ultrasonic power is 250 W), stand for 10 min after completion, and then separate the modified ferrosilicon slag I, denoted as modified ferrosilicon slag II.

[0061] (4) Mix the heated and melted paraffin liquid and graphene at a mass ratio of 10:0.5, ultrasonically disperse to form a coating liquid. Then immerse the modified ferrosilicon slag II in the coating liquid for coating, and then take out the modified ferrosilicon slag II. After cooling to room temperature, a coating layer with a thickness of 0.3 mm is formed on the surface of the modified ferrosilicon slag II to obtain the gas-driven repair particles.

[0062] 2. Prepare raw materials in the following weight ratio: 500 parts by weight of 42.5 Portland cement, 380 parts by weight of the gas-driven repair particles prepared in this example, 356 parts by weight of river sand, 90 parts by weight of steel slag powder, 58 parts by weight of aluminum sulfate powder, 30 parts by weight of short-cut carbon fibers with a length of 10 mm, 440 parts by weight of mixing water, and 20 parts by weight of polycarboxylate water reducer. Mix the above raw materials and stir evenly to obtain the gas-driven repair material.

[0063] 3. Test the compressive strength and capillary water absorption of the concrete test blocks repaired with the gas-driven repair material prepared in this example in the same manner as in Example 1 above, except that the heating power of the wave heating is 700 W, the frequency is 15 GHz, and the heating time is 120 seconds. The test results are: compressive strength = 52.91 MPa, capillary water absorption = 2.2 mm.

[0064] Example 4

[0065] A preparation method of a gas-driven repair material for concrete cracks, comprising the following steps:

[0066] 1. Preparation of gas-driven repair particles, comprising the following steps:

[0067] (1) Mix ferrosilicon slag with a particle size distribution between 1 and 2 mm and a 25% sulfuric acid solution in a ratio of 1 g: 30 ml, stir evenly, and let stand for 1 h for acid leaching treatment. After adding sodium bicarbonate to neutralize the residual sulfuric acid, filter out the solid product to obtain modified ferrosilicon slag I, and collect the filtrate for later use.

[0068] (2) Add sodium borohydride to the filtrate to form a liquid-phase reaction system with a mass fraction of 11%, and then ultrasonically treat the liquid-phase reaction system for 20 min with an ultrasonic power of 450 W. After the precipitation ends, centrifuge to separate the solid product and collect the supernatant of the centrifugation. Vacuum dry the solid product at 90 °C for 50 min to obtain metal micropowder. Add sulfuric acid to the supernatant to eliminate the residual sodium borohydride to obtain mixing water for later use.

[0069] (3) Mix tetraethoxysilane liquid, calcium bicarbonate powder, and the metal micropowder prepared in this example in a ratio of 1 L: 2 g: 7.5 g, ultrasonically disperse for 12 min (ultrasonic power is 500 W) to form a suspension mixture. Then mix the modified ferrosilicon slag I with the suspension mixture in a ratio of 1 g: 30 ml, ultrasonically treat for 5 min (ultrasonic power is 300 W), let stand for 15 min after completion, and then separate the modified ferrosilicon slag I, denoted as modified ferrosilicon slag II.

[0070] (4) Mix the heated and melted paraffin liquid with graphene in a mass ratio of 10:1.5, and then ultrasonically disperse to form a coating liquid. Then immerse the modified ferrosilicon slag II into the coating liquid for coating, and then take out the modified ferrosilicon slag II. After cooling to room temperature, a coating layer with a thickness of 0.4 mm is formed on the surface of the modified ferrosilicon slag II, thus obtaining the gas-driven repair particles.

[0071] 2. Prepare raw materials in the following weight ratio: 400 parts by weight of 42.5 Portland cement, 320 parts by weight of the gas-driven repair particles prepared in this example, 305 parts by weight of river sand, 45 parts by weight of steel slag powder, 25 parts by weight of aluminum sulfate powder, 24 parts by weight of short-cut carbon fibers with a length of 6 mm, 390 parts by weight of mixing water, and 16 parts by weight of polycarboxylate water reducer. Mix the above raw materials evenly, and thus obtain the gas-driven repair material.

[0072] 3. Test the compressive strength and capillary water absorption of the concrete test blocks repaired with the gas-driven repair material prepared in this example in the same manner as in Example 1 above, except that the heating power of the wave heating is 1000 W, the frequency is 5 GHz, and the heating time is 150 seconds. The test results are: compressive strength = 52.23 MPa, capillary water absorption = 2.7 mm.

[0073] Example 5

[0074] A preparation method of a gas-driven repair material for concrete cracks, which is the same as that in Example 1 above, except that step (3) of the preparation method of the gas-driven repair particles is: Mix tetraethoxysilane liquid and the metal fine powder prepared in this example in a ratio of 1 L:7 g, and then ultrasonically disperse for 15 min (ultrasonic power is 350 W) to form a suspension mixture. Then mix the modified ferrosilicon slag I with the suspension mixture in a ratio of 1 g:35 ml, and ultrasonically treat for 10 min (ultrasonic power is 200 W). After completion, let it stand for 15 min, and then separate the modified ferrosilicon slag I, which is the modified ferrosilicon slag II.

[0075] Test the compressive strength and capillary water absorption of the concrete test blocks repaired with the gas-driven repair material prepared in this example in the same manner as in Example 1 above. The results are: compressive strength = 44.37 MPa, capillary water absorption = 6.4 mm.

[0076] Example 6

[0077] A preparation method of a gas-driven repair material for concrete cracks is the same as that of Example 1 above, except that step (3) of the preparation method of the gas-driven repair particles is as follows: Tetraethoxysilane liquid and sodium bicarbonate powder are mixed in a ratio of 1L:1.5g and then ultrasonically dispersed for 15 min (ultrasonic power is 350W) to form a suspension mixture. Then, the modified ferrosilicon slag I and the suspension mixture are mixed in a ratio of 1g:35ml and ultrasonically treated for 10 min (ultrasonic power is 200W). After completion, it is left standing for 15 min, and then the modified ferrosilicon slag I is separated, denoted as modified ferrosilicon slag II.

[0078] The compressive strength and capillary water absorption of the concrete test block repaired with the gas-driven repair material prepared in this example were tested in the same manner as in Example 1 above. The results were: compressive strength = 46.82 MPa, capillary water absorption = 6.1 mm.

[0079] Example 7

[0080] A preparation method of a gas-driven repair material for concrete cracks is the same as that of Example 4 above, except that step (3) of the preparation method of the gas-driven repair particles is as follows: Molten paraffin liquid, calcium bicarbonate powder and the metal micropowder prepared in this example are mixed in a ratio of 1L:2g:7.5g and then ultrasonically dispersed for 12 min (ultrasonic power is 500W) to form a suspension mixture. Then, the modified ferrosilicon slag I and the suspension mixture are mixed in a ratio of 1g:30ml and ultrasonically treated for 5 min (ultrasonic power is 300W). After completion, it is left standing for 15 min, and then the modified ferrosilicon slag I is separated, which is the modified ferrosilicon slag II.

[0081] The compressive strength and capillary water absorption of the concrete test block repaired with the gas-driven repair material prepared in this example were tested in the same manner as in Example 4 above. The results were: compressive strength = 48.06 MPa, capillary water absorption = 5.3 mm.

[0082] Example 8

[0083] A preparation method of a gas-driven repair material for concrete cracks is the same as that of Example 2 above, except that step (4) of the preparation method of the gas-driven repair particles is as follows: The modified ferrosilicon slag II is immersed in molten paraffin liquid for coating, and then the modified ferrosilicon slag II is taken out. After cooling to room temperature, a coating layer with a thickness of 0.5 mm is formed on the surface of the modified ferrosilicon slag II, and thus the gas-driven repair particles are obtained.

[0084] The compressive strength and capillary water absorption of the concrete specimens repaired with the gas-driven repair material prepared in this example were tested in the same manner as in Example 2 above. The results were: compressive strength = 46.18 MPa, capillary water absorption = 4.9 mm.

[0085] Example 9

[0086] A preparation method of a gas-driven repair material for concrete cracks is the same as that in Example 3 above, except that: in the preparation method of the gas-driven repair particles, step (4) is not included, that is, the modified ferrosilicon slag II prepared in step (3) is used as the gas-driven repair particles in this example.

[0087] The compressive strength and capillary water absorption of the concrete specimens repaired with the gas-driven repair material prepared in this example were tested in the same manner as in Example 3 above. The results were: compressive strength = 45.31 MPa, capillary water absorption = 5.1 mm.

[0088] Example 10

[0089] A preparation method of a gas-driven repair material for concrete cracks is the same as that in Example 4 above, except that: step (3) of the preparation method of the gas-driven repair particles is: tetraethoxysilane liquid, calcium bicarbonate powder and the metal micropowder prepared in this example are mixed in a ratio of 1 L: 2 g: 7.5 g, and then ultrasonically dispersed for 12 min (ultrasonic power is 500 W) to form a suspension mixture. Then, the ferrosilicon slag without any acid leaching treatment is mixed with the suspension mixture in a ratio of 1 g: 30 ml and ultrasonically treated for 5 min (ultrasonic power is 300 W). After completion, it is left standing for 15 min, and then the modified ferrosilicon slag I is separated, denoted as modified ferrosilicon slag II.

[0090] The compressive strength and capillary water absorption of the concrete specimens repaired with the gas-driven repair material prepared in this example were tested in the same manner as in Example 4 above. The results were: compressive strength = 49.52 MPa, capillary water absorption = 3.2 mm.

[0091] Example 11

[0092] A preparation method of a gas-driven repair material for concrete cracks, which is the same as Example 2 above, except that step (2) of the preparation method of the gas-driven repair particles is as follows: Sodium borohydride is added to the filtrate to form a liquid-phase reaction system with a mass fraction of 7%, and then the liquid-phase reaction system is ultrasonically treated for 20 min with an ultrasonic power of 500 W. After the precipitation of the precipitated substances is completed, the solid product is separated by centrifugation, and the supernatant of the centrifugation is collected. The solid product is vacuum-dried at 80 °C for 55 min to obtain metal micropowder. The supernatant is used as the mixing water in this example.

[0093] 3. Test the compressive strength and capillary water absorption of the concrete test block repaired with the gas-driven repair material prepared in this example in the same manner as in Example 2 above. The results are: compressive strength = 47.66 MPa, capillary water absorption = 4.7 mm.

[0094] Example 12

[0095] The preparation of a gas-driven repair material for concrete cracks includes the following steps: Prepare raw materials in the following weight ratio: 500 parts by weight of 42.5 Portland cement, 380 parts by weight of the gas-driven repair particles prepared in this example, 356 parts by weight of river sand, 90 parts by weight of steel slag powder, 30 parts by weight of short-cut carbon fibers with a length of 10 mm, 440 parts by weight of mixing water, and 20 parts by weight of polycarboxylate water reducer. Mix the above raw materials evenly and stir well to obtain the gas-driven repair material.

[0096] Test the compressive strength and capillary water absorption of the concrete test block repaired with the gas-driven repair material prepared in this example in the same manner as in Example 3 above. The results are: compressive strength = 50.39 MPa, capillary water absorption = 3.6 mm.

[0097] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A pneumatically-driven repair material for concrete cracks, characterized in that The raw material composition of the material includes: 120 - 500 parts by weight of portland cement, 95 - 380 parts by weight of gas-driven repair particles, 72 - 356 parts by weight of sand, 30 - 90 parts by weight of steel slag powder, 20 - 58 parts by weight of aluminum sulfate powder, 12 - 30 parts by weight of fiber, 200 - 440 parts by weight of mixing water, and 5 - 20 parts by weight of water reducing agent; wherein: the gas-driven repair particles are prepared by the following method: (1) Immerse ferrosilicon slag in sulfuric acid for acid leaching treatment. After completion, separate the solid product to obtain modified ferrosilicon slag I, and collect the separated liquid phase for later use; (2) Add an alkaline substance to the liquid phase to neutralize the residual sulfuric acid, then add sodium borohydride and simultaneously perform ultrasonic treatment. After the precipitation of the precipitate ends, separate the solid product and collect the separated liquid. Vacuum dry the solid product to obtain metal micropowder. Add sulfuric acid to the separated liquid to eliminate the residual sodium borohydride to obtain the mixing water for later use; (3) Mix tetraethoxysilane liquid, bicarbonate powder and the metal micropowder and ultrasonically disperse to form a suspension mixture. Then immerse the modified ferrosilicon slag I in the suspension mixture for ultrasonic treatment. After completion, let it stand, and then separate the modified ferrosilicon slag I to obtain modified ferrosilicon slag II; (4) Form a coating liquid from molten paraffin liquid and graphene. Immerse the modified ferrosilicon slag II in the coating liquid for coating, and then take out the modified ferrosilicon slag II. After cooling, a coating layer is formed on its surface to obtain the gas-driven repair particles.

2. The concrete crack air-driven repair material according to claim 1, wherein In step (1), the material-liquid ratio of the ferrosilicon slag to sulfuric acid is 1 g: 20 - 30 ml.

3. The gas-driven repair material for concrete cracks according to claim 2, wherein The mass fraction of the sulfuric acid is 20 - 35%.

4. The concrete crack air-driven repair material according to claim 1, wherein, In step (1), the particle size of the ferrosilicon slag is between 1 - 3 mm.

5. The gas-driven repair material for concrete cracks according to claim 1, characterized in that In step (2), the alkaline substance includes at least one of sodium hydroxide, sodium carbonate, and sodium bicarbonate.

6. The gas-driven repair material for concrete cracks according to claim 1, characterized in that, In step (2), the mass fraction of sodium borohydride in the system is 7 - 11%.

7. The gas-driven repair material for concrete cracks according to claim 1, wherein In step (2), the time of the ultrasonic treatment is 20 - 25 min, and the ultrasonic power is 300 - 500 W.

8. The gas-driven repair material for concrete cracks according to claim 1, wherein, In step (2), the drying temperature is 80 - 95 °C, and the time is 40 - 55 min.

9. The gas-driven repair material for concrete cracks according to claim 1, wherein In step (3), the ratio of the tetraethoxysilane liquid, bicarbonate powder, and metal micropowder is 1 L: 1 - 2 g: 5 - 8 g.

10. The concrete crack gas-driven repair material according to claim 1, characterized in that, In step (3), the time of the ultrasonic dispersion is 10 - 15 min, and the ultrasonic power is 300 - 500 W.

11. The concrete crack air-driven repair material according to claim 1, characterized in that, In step (3), the bicarbonate includes at least one of sodium bicarbonate, calcium bicarbonate, and magnesium bicarbonate.

12. The concrete crack air-driven repair material according to claim 1, wherein, In step (3), the material-liquid ratio of the modified ferrosilicon slag I to the suspension mixture is 1 g: 30 - 40 ml.

13. The concrete crack air-driven repair material according to claim 1, characterized in that, In step (3), the time of the ultrasonic treatment is 5 - 10 min, the ultrasonic power is 200 - 300 W, and the standing time is 10 - 20 min.

14. The gas-driven repair material for concrete cracks according to claim 1, characterized in that, In step (4), the ratio of the molten paraffin liquid to graphene is 10 parts by weight: 0.8 - 1.5 parts by weight.

15. The concrete crack air-driven repair material according to claim 1, wherein, In step (4), the thickness of the coating layer is controlled below 0.5 mm.

16. The concrete crack gas-driven repair material according to claim 1, wherein The fiber includes any one of glass fiber and carbon fiber.

17. The gas-driven repair material for concrete cracks according to claim 1, characterized in that, The length of the fiber is 5 to 10 mm.

18. The method for using the gas-driven repair material for concrete cracks according to any one of claims 1-17, characterized in that, It includes the following steps: (i) Mix the raw material components of the gas-driven repair material for concrete cracks evenly to obtain the gas-driven repair material for standby; (ii) Inject the gas-driven repair material into the cracks of the concrete structure, then perform microwave heating treatment on the gas-driven repair material, and natural curing can be carried out after completion.

19. The method of using the gas-driven repair material for concrete cracks according to claim 18, characterized in that, The microwave heating frequency is 5 to 20 GHz, the power is 600 to 1000 W, and the heating time is 30 to 150 s.

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