Geopolymer grouting material for repairing road cracks and preparation method of geopolymer grouting material

Abstract

The invention provides a geopolymer grouting material for repairing road cracks and a preparation method of the geopolymer grouting material, and relates to the technical field of highway engineering maintenance, the geopolymer grouting material comprises 50%-70% of a silicon-aluminum base material, 5%-15% of a soil ion exchanger, 3%-8% of an anti-freezing solution, 10%-20% of an alkali activator and 0.5%-2% of an admixture, the silicon-aluminum base material forms a high-strength framework under the action of the alkali activator, and the soil ion exchanger is added into the high-strength framework; the soil ion exchanger improves interface bonding, the anti-freezing solution guarantees low-temperature fluidity, the admixture improves comprehensive performance, stability of a base layer and structural layers below the base layer is guaranteed, a roadbed is reinforced, the bearing capacity of a road structure is improved, the strength of the road structure is homogenized, and after geopolymer grouting reinforcement is utilized, an asphalt surface layer is milled and planed. And special micro-crack equipment is adopted to carry out micro-crack treatment on the semi-rigid base layer of the asphalt pavement, and the semi-rigid base layer is converted into a permanent pavement structure layer, so that the improvement and paving of the durable or long-life asphalt pavement are realized.

Description

Technical Field

[0001] The present invention relates to the technical field of highway engineering maintenance, and particularly relates to a geopolymer grouting material for road crack repair and a preparation method thereof. Background Art

[0002] The road surface structure consists of an asphalt surface layer, a water-stabilized layer, and a soil base layer from top to bottom. When cracks appear on the road surface above the soil base layer, surface water will seep into the soil base layer, scouring the soil to form void diseases.

[0003] Currently, for the problem of voids, the conventional repair method is to drill holes to the soil base layer at the void location and then pour cement. However, the interfacial bonding between cement and the soil base layer is poor. Especially in a low-temperature environment, the fluidity of the cement slurry decreases significantly, resulting in the void repair effect being difficult to meet the engineering requirements. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the defects of traditional cement-based materials in the repair of low-temperature loess base layers in the prior art. The present invention provides a geopolymer grouting material with good low-temperature fluidity, excellent binding property with soil, and corrosion resistance, as well as a preparation method thereof, so as to achieve efficient repair and long-term maintenance of road base cracks.

[0005] To solve the above technical problem, the technical solution adopted by the present invention is a geopolymer grouting material for road crack repair, including the following components by mass percentage: 50% - 70% of a silicoaluminous base material, and the silicoaluminous base material consists of 20% - 30% of metakaolin, 15% - 25% of fly ash, and 15% - 20% of ground granulated blast-furnace slag; 5% - 15% of a soil ion exchanger, and the soil ion exchanger is a modified attapulgite or humic acid complex with surface-grafted hydroxyl / carboxyl functional groups; 3% - 8% of an antifreeze, and the antifreeze is a compound solution of ethylene glycol and glycerol, with a volume ratio of 1:1 - 2:1; 10% - 20% of an alkali activator, and the alkali activator is a mixed solution of sodium hydroxide solution and water glass, with a mass ratio of 1:1 - 1:2; 0.5% - 2% of an admixture, and the admixture includes 0.3% - 1% of a polycarboxylate water-reducing agent and 0.2% - 1% of polypropylene fiber.

[0006] Furthermore, the active alumina content of the metakaolin is not less than 35%, the specific surface area is between 1000 - 1500 m² / kg, the fly ash is fly ash of grade II or above, the residue fineness of the square-hole sieve is 45 μm, the specific surface area of the ground granulated blast-furnace slag is not less than 400 m² / kg, and the activity index is not less than 75% at 7 days and not less than 95% at 28 days.

[0007] Further, the cation exchange capacity of the modified attapulgite is not less than 100 mmol / 100 g, and the humic acid content in the humic acid complex is not less than 60%.

[0008] Further, the purity of the ethylene glycol is not less than 99%, and the purity of the glycerol is not less than 98%.

[0009] Further, the concentration of the sodium hydroxide solution is 8 - 12 mol / L, the modulus of the sodium silicate is 2.5 - 3.5, and the concentration is 35% - 40%.

[0010] Further, the water reducing rate of the polycarboxylate water reducer is not less than 25%, the length of the polypropylene fiber is 6 - 12 mm, and the diameter is 18 - 30 μm.

[0011] Further, the attapulgite is calcined at 300 - 500 °C for 2 - 4 hours, then soaked in an acid solution with a concentration of 2 - 5 mol / L for 12 - 24 hours, and then graft-modified with an organic reagent containing hydroxyl and carboxyl functional groups to obtain the modified attapulgite.

[0012] Further, the humic acid complex is obtained by mixing humic acid and bentonite in a mass ratio of 3:1 - 5:1 and reacting at 80 - 120 °C for 3 - 6 hours.

[0013] Further, the surface of the polypropylene fiber is treated with a silane coupling agent, and the dosage of the silane coupling agent is 0.5% - 1.5% of the mass of the polypropylene fiber.

[0014] Another technical solution provided by the present invention is a preparation method of a geopolymer grouting material for road crack repair, including the following steps: S1: Preparation of silicoaluminous powder: Conduct quality inspection on metakaolin, fly ash, and slag powder, accurately weigh them according to the ratio, put them into a ball mill and mill for 30 - 60 minutes. During this period, check the grinding situation, and after grinding, detect the particle size to ensure that the average particle size is not greater than 50 μm. After passing through a 200 - mesh sieve, store it for standby; S2: Pretreatment of soil ion exchanger: Dry the modified attapulgite or humic acid complex in an environment of 60 - 80 °C for 2 - 4 hours, detect the moisture to ensure it is lower than 1%, crush it and control the speed and strength, and store it sealed after passing through a 100 - mesh sieve; S3: Dry mixing treatment: Weigh the silicoaluminous powder, the treated soil ion exchanger, the polycarboxylate water reducer, and the polypropylene fiber according to the formula. After checking the forced mixer, add the materials and dry mix at medium speed for 5 - 10 minutes to ensure uniformity; S4: Solution preparation: Measure ethylene glycol and glycerol according to the ratio and mix them evenly to obtain antifreeze. Weigh sodium hydroxide to prepare a solution. After the solution cools, mix it with the measured sodium silicate according to the ratio to form an alkali activator solution, and store them separately for standby; S5: Preliminary wetting: The dry-mixed materials are stirred at a low speed in a blender, and the antifreeze is slowly added while observing the wetting condition. After the addition, continue stirring for 3 - 5 minutes. S6: Wet mixing and forming: Install a temperature sensor, slowly add the alkali activator solution and control the temperature at 15 - 25 °C, and perform high-speed wet mixing for 8 - 15 minutes. During this period, check the fluidity and uniformity. After the wet mixing is completed, comprehensively detect the performance. After passing the inspection, seal and package for storage.

[0015] Compared with the prior art, the present invention includes 50% - 70% of silicoaluminous base material, 5% - 15% of soil ion exchanger, 3% - 8% of antifreeze, 10% - 20% of alkali activator, and 0.5% - 2% of admixture. Under the action of the alkali activator, the silicoaluminous base material forms a high-strength framework. The soil ion exchanger improves the interfacial bonding. The antifreeze ensures the low-temperature fluidity. The admixture enhances the comprehensive performance. In a low-temperature environment, the antifreeze composed of the compound of ethylene glycol and glycerol ensures the fluidity of the slurry, ensuring that it can still penetrate into fine cracks at -5 to -15 °C. In terms of interfacial bonding, the modified attapulgite or humic acid complex generates ion exchange and chemical bonding with the loess base layer through surface functional groups, inhibiting the alkali-aggregate reaction, and significantly improving the bonding strength compared with traditional materials. In terms of durability performance, the silicoaluminous base material forms a high-strength cementitious structure under the action of alkali activation, combined with polypropylene fibers to enhance toughness, and the material has excellent resistance to sulfate erosion and freeze-thaw cycles. By filling and reinforcing, and compressing and densifying, the voids at the bottom of the base are eliminated, stabilizing the base and the underlying structural layers. At the same time, the roadbed is reinforced and the bearing capacity of the road structure is balanced. After grouting reinforcement, the asphalt surface layer is further milled, and the base is subjected to micro-crack treatment with special equipment, converting it into a permanent road surface structural layer, realizing the reconstruction and overlay of durable or long-life asphalt pavements. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The disclosure of the present invention will be described with reference to the accompanying drawings. It should be understood that the drawings are only for illustrative purposes and are not intended to limit the scope of protection of the present invention. In the drawings, the same reference numerals are used to refer to the same components. Among them: Figure 1 Schematically shows a flowchart of a geopolymer grouting material for road crack repair and its preparation method according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0017] It is easily understood that according to the technical solution of the present invention, without changing the essence of the present invention, those of ordinary skill in the art can propose various alternative structural forms and implementation methods. Therefore, the following detailed embodiments and the accompanying drawings are only illustrative descriptions of the technical solution of the present invention, and should not be regarded as the whole of the present invention or as a limitation or restriction on the technical solution of the present invention.

[0018] According to an embodiment of the present invention, in combination with Figure 1 Shown. A geopolymer grouting material for road crack repair and its preparation method. The technical solutions of the present invention will be further described below through three embodiments. Embodiment

[0019] Mix metakaolin, fly ash, and ground granulated blast-furnace slag in proportion and ball-mill them. Treat the soil ion exchanger, and prepare the geopolymer grouting material through dry mixing, solution preparation, and wet mixing, as follows: The formula composition is as follows: Silico-aluminous base material 60%: The proportion of metakaolin is 25%, its active alumina content is 38%, and the specific surface area is 1200 m² / kg; The proportion of fly ash is 20%, which is Class II fly ash, and the residue on a 45-μm square-hole sieve is 18%; The proportion of ground granulated blast-furnace slag is 15%, the specific surface area is 450 m² / kg, and the activity index is 80% at 7 days and 98% at 28 days.

[0020] Soil ion exchanger 10%: Modified attapulgite, with a cation exchange capacity of 120 mmol / 100 g and surface-grafted hydroxyl functional groups; Antifreeze 5%: Ethylene glycol and glycerol are compounded at a volume ratio of 1.5:1. The purity of ethylene glycol is 99.5%, and the purity of glycerol is 98.5%.

[0021] Alkali activator 18%: Prepared by mixing a sodium hydroxide solution with a concentration of 10 mol / L and sodium silicate with a modulus of 3.0 and a concentration of 38% in a mass ratio of 1:1.5; Admixture 2%: The proportion of polycarboxylate superplasticizer is 0.8%, and the water reduction rate is 28%; The proportion of polypropylene fiber is 1.2%, the fiber length is 9 mm, the diameter is 22 μm, and it is treated with a silane coupling agent, and the treatment amount is 1% of the mass of the polypropylene fiber; The preparation steps are as follows: Silico-aluminous powder: Mix metakaolin, fly ash, and ground granulated blast-furnace slag and ball-mill for 45 minutes, then pass through a 200-mesh sieve. The average particle size of the obtained powder is 40 μm; Soil ion exchanger: Dry the modified attapulgite at 70 °C for 3 hours, crush it, and then pass through a 100-mesh sieve; Dry mixing: Add the silico-aluminous powder, modified attapulgite, polycarboxylate superplasticizer, and polypropylene fiber into a forced mixer and dry mix for 8 minutes to ensure uniform mixing of each component; Solution preparation: Measure ethylene glycol and glycerol in proportion and mix them evenly to obtain antifreeze; dissolve sodium hydroxide in water and then mix it with water glass to prepare an alkali activator solution; Wet mixing: Under low-speed stirring, slowly add the antifreeze to the dry-mixed materials, stir for 4 minutes to make them preliminarily wet, and then add the alkali activator solution. Control the stirring temperature at 20°C and perform high-speed wet mixing for 12 minutes until the slump of the slurry reaches 230 mm; The performance test results of the geopolymer grouting material prepared in Example 1 are shown in Table 1:

[0022] Table 1 Example

[0023] By adjusting the raw material ratio and preparation parameters, prepare a humic acid complex type geopolymer grouting material, the details are as follows: The formula composition is as follows: Silico-aluminous substrate 55%: The proportion of metakaolin is 22%, its active alumina content is 36%, and the specific surface area is 1100 m² / kg; The proportion of fly ash is 18%, which is Class II fly ash, and the residue on a 45μm square hole sieve is 20%; The proportion of ground granulated blast-furnace slag is 15%, the specific surface area is 420 m² / kg, and the activity index is 78% at 7 days and 96% at 28 days.

[0024] Soil ion exchanger 12%: Humic acid complex, in which the humic acid content is 65%, which is prepared by mixing humic acid and bentonite in a mass ratio of 4:1 and reacting at 80-120°C for 3-6 hours; Antifreeze 6%: Ethylene glycol and glycerol are compounded in a volume ratio of 1.3:1; Alkali activator 19%: Prepared by mixing a sodium hydroxide solution with a concentration of 9 mol / L and water glass with a modulus of 2.8 and a concentration of 36% in a mass ratio of 1:1.6.

[0025] Admixture 1.5%: The proportion of polycarboxylate superplasticizer is 0.6%, and the water reduction rate is 26%; The proportion of polypropylene fiber is 0.9%, the fiber length is 7 mm, the diameter is 20μm, and it is treated with a silane coupling agent, and the treatment amount is 0.8% of the mass of the polypropylene fiber.

[0026] The preparation steps are as follows: Silico-aluminous powder: Mix metakaolin, fly ash, and ground granulated blast-furnace slag and ball mill for 40 minutes. The average particle size of the powder obtained after sieving is 45μm; Soil ion exchanger: Dry the humic acid complex at 65 °C for 3 hours, crush it and sieve it through a 100-mesh sieve; Wet mixing: Mix the pretreated materials with antifreeze and alkali activator, control the stirring temperature at 18 °C, and wet mix for 10 minutes to obtain a uniform slurry with a slump of 210 mm.

[0027] The performance test results of the geopolymer grouting material prepared in Example 2 are shown in Table 2:

[0028] Table 2 Example

[0029] For high cold resistance requirements, adjust the formula and process to prepare the geopolymer grouting material. The details are as follows: The formula composition is as follows: Silico-aluminous substrate 50%: The proportion of metakaolin is 30%, its active alumina content is 40%, and the specific surface area is 1300 m² / kg; The proportion of fly ash is 15%, which is Class II fly ash, and the residue on a 45-μm square-hole sieve is 22%; The proportion of ground granulated blast-furnace slag is 15%, the specific surface area is 400 m² / kg, and the activity index is 75% at 7 days and 95% at 28 days.

[0030] Soil ion exchanger 15%: Modified attapulgite, with a cation exchange capacity of 110 mmol / 100 g.

[0031] Antifreeze 8%: Ethylene glycol and glycerol are compounded at a volume ratio of 2:1.

[0032] Alkali activator 20%: Prepared by mixing sodium hydroxide solution with a concentration of 12 mol / L and water glass with a modulus of 3.5 and a concentration of 40% at a mass ratio of 1:1.

[0033] Admixture 2%: The proportion of polycarboxylate superplasticizer is 1%, and the water reduction rate is 25%; The proportion of polypropylene fiber is 1%, the fiber length is 12 mm, the diameter is 30 μm, and it is treated with a silane coupling agent, and the treatment amount is 1.5% of the mass of the polypropylene fiber.

[0034] The preparation steps are as follows: Silico-aluminous powder: Mix metakaolin, fly ash, and ground granulated blast-furnace slag, then ball mill for 60 minutes, and the average particle size of the powder obtained after sieving is 35 μm; Wet mixing: Mix the pretreated materials with antifreeze and alkali activator, control the stirring temperature at 25°C, and wet mix for 15 minutes to obtain a uniform slurry with a slump of 200 mm.

[0035] The performance test results of the geopolymer grouting material prepared in Example 3 are shown in Table 3 as follows:

[0036] Table 3 Specifically, under the action of the mixed solution of sodium hydroxide solution and water glass as the alkali activator, the aluminosilicate substrate undergoes a geopolymerization reaction to form a high-strength structure, constituting the strength skeleton of the material. The modified attapulgite or humic acid complex of the soil ion exchanger undergoes ion exchange and chemical bonding with the loess base layer through surface functional groups, improving the interfacial bonding and inhibiting the alkali-aggregate reaction. The antifreeze composed of the compound of ethylene glycol and glycerol reduces the freezing point of the system to ensure low-temperature fluidity. The polycarboxylate superplasticizer improves fluidity, and the polypropylene fiber enhances toughness, jointly optimizing the comprehensive performance of the material. By ball milling and screening the aluminosilicate substrate, drying and pulverizing the soil ion exchanger, then dry mixing the solid components evenly, preparing the antifreeze and alkali activator solution, and finally controlling the temperature for wet mixing and molding. Through steps such as raw material pretreatment and mixing reaction, the material has both low-temperature fluidity, interfacial adhesiveness, and durable corrosion resistance, precisely meeting the repair requirements of cracks in low-temperature loess base roads.

[0037] The technical scope of the present invention is not limited to the content described above. Those skilled in the art can make various deformations and modifications to the above embodiments without departing from the technical idea of the present invention, and these deformations and modifications should all fall within the protection scope of the present invention.

Claims

1. A geopolymer grouting material for road crack repair, characterized in that, It comprises the following components by mass percentage: 50% - 70% of aluminosilicate base material, and the aluminosilicate base material consists of 20% - 30% of metakaolin, 15% - 25% of fly ash, and 15% - 20% of granulated blast-furnace slag powder; 5% - 15% of soil ion exchanger, and the soil ion exchanger is modified attapulgite grafted with hydroxyl / carboxyl functional groups on the surface or humic acid complex; 3% - 8% of antifreeze, and the antifreeze is a compound solution of ethylene glycol and glycerol, with a volume ratio of 1:1 - 2:1; 10% - 20% of alkali activator, and the alkali activator is a mixture of sodium hydroxide solution and water glass, with a mass ratio of 1:1 - 1:2; 0.5% - 2% of admixture, and the admixture includes 0.3% - 1% of polycarboxylate water reducer and 0.2% - 1% of polypropylene fiber.

2. The geopolymer grouting material for road crack repair according to claim 1, wherein, The active alumina content of the metakaolin is not less than 35%, the specific surface area is between 1000 - 1500 m² / kg, the fly ash is fly ash above grade II, the residue fineness of the square hole sieve is 45μm, the specific surface area of the granulated blast-furnace slag powder is not less than 400 m² / kg, and the activity index is not less than 75% at 7 days and not less than 95% at 28 days.

3. The geopolymer grouting material for road crack repair according to claim 1, characterized in that, The cation exchange capacity of the modified attapulgite is not less than 100 mmol / 100g, and the humic acid content in the humic acid complex is not less than 60%.

4. The geopolymer grouting material for road crack repair according to claim 1, wherein, The purity of the ethylene glycol is not less than 99%, and the purity of the glycerol is not less than 98%.

5. The geopolymer grouting material for road crack repair according to claim 1, wherein, The concentration of the sodium hydroxide solution is 8 - 12 mol / L, the modulus of the water glass is 2.5 - 3.5, and the concentration is 35% - 40%.

6. The geopolymer grouting material for road crack repair according to claim 1, characterized in that The water reduction rate of the polycarboxylate water reducer is not less than 25%, the length of the polypropylene fiber is 6 - 12 mm, and the diameter is 18 - 30μm.

7. The geopolymer grouting material for road crack repair according to claim 1, characterized in that, The attapulgite is calcined at 300 - 500°C for 2 - 4 hours, then soaked in an acid solution with a concentration of 2 - 5 mol / L for 12 - 24 hours, and then graft-modified with an organic reagent containing hydroxyl and carboxyl functional groups to obtain modified attapulgite.

8. The geopolymer grouting material for road crack repair according to claim 1, characterized in that, The humic acid complex is obtained by mixing humic acid and bentonite in a mass ratio of 3:1 - 5:1 and reacting at 80 - 120°C for 3 - 6 hours.

9. The geopolymer grouting material for road crack repair according to claim 1, characterized in that, The surface of the polypropylene fiber is treated with a silane coupling agent, and the dosage of the silane coupling agent is 0.5% - 1.5% of the mass of the polypropylene fiber.

10. A preparation method of a geopolymer grouting material for road crack repair, which is used to prepare the geopolymer grouting material for road crack repair as described in claims 1-9, characterized in that, It includes the following steps: S1: Preparation of aluminosilicate powder: Conduct quality inspection on metakaolin, fly ash, and granulated blast-furnace slag powder, accurately weigh them according to the proportion and put them into a ball mill for ball milling for 30 - 60 minutes. During this period, check the grinding situation, and after ball milling, detect the particle size to ensure that the average particle size is not greater than 50μm. After passing through a 200-mesh sieve, store it for standby; S2: Pretreatment of soil ion exchanger: Dry the modified attapulgite or humic acid complex in an environment of 60 - 80°C for 2 - 4 hours, detect the moisture to ensure it is lower than 1%, crush it and control the speed and strength, and store it sealed after passing through a 100-mesh sieve; S3: Dry mixing treatment: Weigh the aluminosilicate powder, pretreated soil ion exchanger, polycarboxylate water reducer, and polypropylene fiber according to the formula, check the compulsory mixer and then add the materials, and dry mix at medium speed for 5 - 10 minutes to ensure uniformity; S4: Solution preparation: Measure ethylene glycol and glycerol in proportion and mix them evenly to obtain the antifreeze. Weigh sodium hydroxide to prepare a solution. After the solution cools down, mix it with the measured water glass in proportion to form an alkali activator solution, and store them separately for standby; S5: Preliminary wetting: The dry-mixed materials are stirred at a low speed in a mixer, and the antifreeze is slowly added while observing the wetting situation. After adding, continue to stir for 3-5 minutes; S6: Wet mixing and molding: Install a temperature sensor, slowly add the alkali activator solution and control the temperature at 15-25 °C, carry out high-speed wet mixing for 8-15 minutes, check the fluidity and uniformity during this period. After the wet mixing is completed, comprehensively detect the performance. After passing the inspection, seal and package for storage.

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