Polymer modified cement pavement repairing mortar and preparation method thereof

Abstract

The invention discloses polymer modified cement pavement patching mortar and a preparation method thereof, and belongs to the field of cement pavement patching materials. The repairing mortar is prepared from the following raw material components: cement, isobutyl methacrylate modified quartz sand, polyethylene glycol composite metakaolin, styrene-butadiene latex, acrylic emulsion, a defoaming agent and a water reducing agent. The cement pavement repairing sand disclosed by the invention is excellent in high temperature resistance, the residual breaking strength at 80 DEG C is 9.1-9.3 MPa, and the residual breaking strength at 100 DEG C is 8.9-9.0 MPa.

Description

TECHNICAL FIELD

[0001] The present application relates to a polymer modified cement pavement repair mortar and a preparation method thereof, and belongs to the field of cement pavement repair materials. BACKGROUND

[0002] Cement concrete pavement, as an important part of urban road and highway traffic, often needs to face different degrees of damage. These damages not only affect the use efficiency and traffic safety of the road, but also bring a huge burden to the road maintenance and management department. Therefore, how to effectively repair these pavement damages has become a hot issue of concern for researchers. At present, there are many different types of rapid road repair materials at home and abroad. These materials can be divided into three main categories according to the performance of the cementing materials they contain: inorganic repair materials, organic polymer repair materials and inorganic-organic composite repair materials.

[0003] Among them, inorganic repair materials mainly rely on the gelation of cement and other inorganic gel materials to inhibit crack development, improve the brittleness defect and durability of concrete. Inorganic repair method has low cost and convenient construction, but also has the disadvantages of easy post-strength reduction, low bonding strength, easy cracking and unevenness, etc.

[0004] Organic polymer repair materials contain polymer, filler, reinforcing material, aggregate and various additives. The development speed of this repair material is fast, and it has the characteristics of rapid solidification, high compressive strength and bonding strength. Compared with inorganic cement repair materials, it has more advantages, but its cost is high and it cannot be used on a large scale.

[0005] Inorganic-organic composite repair materials are composed of polymer and inorganic gel materials. They are more effective than inorganic cement or organic composite materials alone because the material has small shrinkage, good impermeability and high bonding strength. Therefore, inorganic-organic composite repair materials have become the key research object of cement concrete pavement repair materials.

[0006] The commonly used organic polymers in inorganic-organic composite repair materials are styrene-butadiene latex (SBR) and acrylic resin (AE). Both have good stability in cement and can be used with various grades of cement. In inorganic-organic composite repair materials, cement particles react with water to form crystalline structures such as hydrated calcium silicate, which constitute a rigid skeleton. As water evaporates and is consumed by cement hydration, SBR and AE emulsion particles approach each other, deform, and fuse, forming a continuous polymer film on the surface of cement hydration products, unhydrated cement particles, and aggregates, forming a network structure. When the material is subjected to external force, the polymer phase can absorb energy through its own deformation, preventing microcracks from expanding into macrocracks, thereby increasing the strength of the repair mortar. Moreover, the two polymers can be used in combination in a certain proportion to achieve a more significant performance improvement than when used alone, especially in terms of compressive strength and flexural strength.

[0007] Both SBR and AE are organic polymers with low glass transition temperatures. When the ambient temperature exceeds their tolerance limit (typically above 70-80℃), the polymer film softens, melts, or even decomposes, losing its bridging and toughening effects. This leads to a sharp decline in the material's mechanical properties (flexural strength, bond strength), increased rigidity, restored brittleness, and increased susceptibility to cracking. This poses a challenge for environments frequently exposed to high temperatures (such as floors in hot regions or factory floors).

[0008] To improve its high-temperature resistance, the usual approach is to reduce the polymer-cement ratio, that is, to reduce the amount of polymer and increase the amount of gel material. Appropriately reducing the amount of polymer can increase the proportion of rigid cement stone skeleton in the material, thereby improving stability at high temperatures. However, this results in a reduction in the material's bonding performance and flexural strength. In the current technology, there is no method to improve the high-temperature resistance of the material while keeping the polymer-cement ratio unchanged. Summary of the Invention

[0009] The technical problem to be solved by this invention is to overcome the defects of the existing technology. Polyethylene glycol composite metakaolin is used as an active admixture, and isobutyl methacrylate modified quartz sand is used as the aggregate of the repair mortar. Combined with cement, polymer and other components in the raw materials, polymer modified cement pavement repair mortar is prepared. The high temperature resistance of the material is improved without sacrificing the flexural strength and bond strength of the material and while ensuring that the polymer-to-ash ratio remains unchanged.

[0010] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: A polymer-modified cement pavement repair mortar, wherein the raw material components of the repair mortar include cement, isobutyl methacrylate modified quartz sand, polyethylene glycol composite metakaolin, styrene-butadiene latex, acrylic emulsion, defoamer, and water-reducing agent, and the mass ratio between the components is 85-115:250-320:45-55:45-55:28-32:0.9-1.1:0.9-1.1.

[0011] The following are further improvements to the above technical solution: The cement is PO42.5 ordinary Portland cement; The styrene to butadiene ratio in the styrene-butadiene latex is 40-60:40-60, and the solid content of the latex is 50 wt%. The acrylic emulsion is designated ADWEL1356, and its solid content is 50 wt%. The defoamer is model JT-930-J0408; The water-reducing agent is PCA-1 polycarboxylate water-reducing agent; The preparation method of the polyethylene glycol composite metakaolin is as follows: Mix 6-hydroxymethylnicotinic acid, polyethylene glycol 200, and polyethylene glycol 600 until homogeneous. Then add p-toluenesulfonic acid and stir under a nitrogen atmosphere at a temperature of 170-177°C for 110-125 minutes. Next, add metakaolin and continue stirring under a nitrogen atmosphere at a temperature of 170-177°C for 55-65 minutes. After stirring, filter, wash, and dry to obtain modified metakaolin. The mass ratio of 6-hydroxymethylnicotinic acid, polyethylene glycol 200, polyethylene glycol 600, p-toluenesulfonic acid, and metakaolin is 175-225:450-550:450-550:0.9-1.1:1750-2250. The D50 of the metakaolin is 4-6 μm.

[0012] The preparation method of the isobutyl methacrylate modified quartz sand is as follows: Sodium silicate is mixed with deionized water and stirred until completely dissolved to obtain a sodium silicate solution. Then, barium titanate is added to the sodium silicate solution and stirred until homogeneous to obtain a mixed solution. Quartz sand is added to the mixed solution, and the temperature is controlled at 45-55℃ while stirring for 25-45 minutes. After stirring, a quartz sand slurry is obtained. Isobutyl methacrylate is added to the quartz sand slurry, and the temperature is controlled at 67-75℃ while stirring for 50-65 minutes. After stirring, the quartz sand is filtered, washed, and dried to obtain modified quartz sand. The mass ratio of sodium silicate to deionized water is 7.0-8.0:100; The amount of barium titanate added is 20-30% of the total mass of sodium silicate; The mass ratio of the quartz sand to the mixed liquid is 2:2.5-3.5; The amount of isobutyl methacrylate added is 2.3-2.7% of the total mass of the quartz sand; The quartz sand is medium-grained quartz with a density of 2670 kg / m³. 3 .

[0013] The method for preparing the repair mortar is as follows: The specified mass of cement, isobutyl methacrylate modified quartz sand, and polyethylene glycol composite metakaolin in the raw material components are mixed and dry-mixed for 45-75 seconds. Then, water is added according to a water-cement ratio of 0.48-0.52. Next, the specified mass of styrene-butadiene latex, acrylic emulsion, defoamer, and water-reducing agent in the raw material components are added. The mixture is stirred for another 280-330 seconds to obtain a polymer-modified cement pavement repair mortar.

[0014] Compared with the prior art, the present invention achieves the following beneficial effects: In the preparation method of polyethylene glycol composite metakaolin, 6-hydroxymethylnicotinic acid and polyethylene glycol are used to modify metakaolin under the catalysis of p-toluenesulfonic acid, forming an organic-inorganic hybrid structure. The core mechanism is that under the acidic catalysis of p-toluenesulfonic acid, 6-hydroxymethylnicotinic acid acts as a multifunctional bridging agent, first bonding with the hydroxyl groups on the surface of metakaolin through esterification and etherification reactions. Subsequently, its other end undergoes a condensation reaction with the terminal hydroxyl groups of polyethylene glycol, thereby establishing a strong covalent bond bridge between the inorganic phase and the organic polymer phase. Ultimately, the covalent bonds, hydrogen bonds, and physical entanglement work together to form a homogeneous and stable organic-inorganic hybrid material. In another method for preparing isobutyl methacrylate modified quartz sand, a layer of silica rich in hydroxyl groups and embedded with barium titanate is first deposited on the surface of quartz sand using sodium silicate. Then, the residual hydroxyl groups on the surface react with isobutyl methacrylate monomers, and organic molecular chains are grafted through covalent bonds to form a three-layer composite with an isobutyl methacrylate organic molecular layer on the surface, a silica and barium titanate intermediate layer in the middle, and quartz sand in the core. Experiments have shown that using polyethylene glycol composite metakaolin as an active admixture and isobutyl methacrylate modified quartz sand as aggregate in the repair mortar, combined with cement, polymer and other components in the raw materials, to prepare polymer-modified cement pavement repair mortar can improve the high-temperature resistance of the material without sacrificing the flexural strength and bond strength of the material and while ensuring that the polymer-to-ash ratio remains unchanged. The cement pavement repair mortar of the present invention has high compressive strength. The test specimens were prepared according to the method in DL / T5126-2021 and their compressive strength was tested. The 3-day compressive strength was 15.3-15.6 MPa, the 7-day compressive strength was 21.1-22.0 MPa, and the 28-day compressive strength was 33.1-33.8 MPa. The cement pavement repair mortar of the present invention has high flexural strength. The specimens were prepared according to the method in DL / T5126-2021 and their flexural strength was tested. The 3-day flexural strength was 7.5-7.6 MPa, the 7-day flexural strength was 8.1-8.3 MPa, and the 28-day flexural strength was 9.2-9.5 MPa. The cement pavement repair mortar of the present invention has high shear bond strength. The specimens were prepared according to the method in DL / T5126-2021 and their shear bond strength was tested. The 3-day shear bond strength was 5.2-5.5 MPa, the 7-day shear bond strength was 6.7-6.9 MPa, and the 28-day shear bond strength was 9.1-9.3 MPa. The cement pavement repair mortar of the present invention has high flexural bond strength. The test specimens were prepared according to the method in DL / T5126-2021 and their flexural bond strength was tested. The 3-day flexural bond strength was 4.5-4.8 MPa, the 7-day flexural bond strength was 5.1-5.3 MPa, and the 28-day flexural bond strength was 5.8-6.0 MPa. The cement pavement repair sand of this invention exhibits excellent high-temperature resistance. Samples were prepared according to the method in DL / T5126-2021 and cured under standard conditions for 28 days. The cured samples were then heated to specified temperatures at a constant rate of 5℃ / min, specifically 80℃ and 100℃. After reaching the specified temperatures, the samples were held at these temperatures for 24 hours and then allowed to cool naturally to room temperature. The residual compressive strength, residual flexural strength, and mass loss of the samples were tested. The residual compressive strength at 80℃ was 31.9-32.7 MPa, and at 100℃ it was 30.6-32.1 MPa. The residual flexural strength at 80℃ was 9.1-9.3 MPa, and at 100℃ it was 8.9-9.0 MPa. The mass loss at 80℃ was 2.0-2.3%, and at 100℃ it was 2.3-2.5%. Detailed Implementation

[0015] Example 1 A polymer-modified cement pavement repair mortar, the raw material components of which include cement, isobutyl methacrylate modified quartz sand, polyethylene glycol composite metakaolin, styrene-butadiene latex, acrylic emulsion, defoamer, and water-reducing agent, with the mass ratio of each component being 100:285:50:50:30:1:1. The cement is PO42.5 ordinary Portland cement; The styrene-butadiene latex has a styrene to butadiene ratio of 60:40 and a solid content of 50 wt%. The acrylic emulsion is designated ADWEL1356, and its solid content is 50 wt%. The defoamer is model JT-930-J0408; The water-reducing agent is PCA-1 polycarboxylate water-reducing agent; The preparation method of the polyethylene glycol composite metakaolin is as follows: 6-Hydroxymethylnicotinic acid, polyethylene glycol 200, and polyethylene glycol 600 were mixed and stirred until homogeneous. Then, p-toluenesulfonic acid was added, and the mixture was stirred at 175°C under a nitrogen atmosphere for 120 minutes. Next, metakaolin was added, and the mixture was stirred at 175°C under a nitrogen atmosphere for 60 minutes. After stirring, the mixture was filtered, washed, and dried to obtain modified metakaolin. The mass ratio of 6-hydroxymethylnicotinic acid, polyethylene glycol 200, polyethylene glycol 600, p-toluenesulfonic acid, and metakaolin is 200:500:500:1:2000. The D50 of the metakaolin is 5 μm.

[0016] The preparation method of the isobutyl methacrylate modified quartz sand is as follows: Sodium silicate was mixed with deionized water and stirred until completely dissolved to obtain a sodium silicate solution. Then, barium titanate was added to the sodium silicate solution and stirred until homogeneous to obtain a mixed solution. Quartz sand was added to the mixed solution and stirred at 50°C for 30 minutes. After stirring, quartz sand slurry was obtained. Isobutyl methacrylate was added to the quartz sand slurry and stirred at 70°C for 60 minutes. After stirring, the quartz sand was filtered, washed, and dried to obtain modified quartz sand. The mass ratio of sodium silicate to deionized water is 7.5:100; The amount of barium titanate added is 25% of the total mass of sodium silicate; The mass ratio of the quartz sand to the mixture is 2:3; The amount of isobutyl methacrylate added is 2.5% of the total mass of the quartz sand; The quartz sand is medium-grained quartz with a density of 2670 kg / m³. 3 .

[0017] The method for preparing the repair mortar is as follows: The specified mass of cement, isobutyl methacrylate modified quartz sand, and polyethylene glycol composite metakaolin in the raw material components are mixed and dry-mixed for 60 seconds. Then, water is added at a water-cement ratio of 0.5. Next, the specified mass of styrene-butadiene latex, acrylic emulsion, defoamer, and water-reducing agent in the raw material components are added. The mixture is stirred for another 300 seconds to obtain a polymer-modified cement pavement repair mortar.

[0018] Example 2 A polymer-modified cement pavement repair mortar, the raw material components of which include cement, isobutyl methacrylate modified quartz sand, polyethylene glycol composite metakaolin, styrene-butadiene latex, acrylic emulsion, defoamer, and water-reducing agent, with the mass ratio of each component being 85:250:45:45:28:0.9:0.9; The cement is PO42.5 ordinary Portland cement; The styrene-butadiene latex has a styrene to butadiene ratio of 50:50 and a solid content of 50 wt%. The acrylic emulsion is designated ADWEL1356, and its solid content is 50 wt%. The defoamer is model JT-930-J0408; The water-reducing agent is PCA-1 polycarboxylate water-reducing agent; The preparation method of the polyethylene glycol composite metakaolin is as follows: 6-Hydroxymethylnicotinic acid, polyethylene glycol 200, and polyethylene glycol 600 were mixed and stirred until homogeneous. Then, p-toluenesulfonic acid was added, and the mixture was stirred at 170°C under a nitrogen atmosphere for 125 minutes. Next, metakaolin was added, and the mixture was stirred at 170°C under a nitrogen atmosphere for 65 minutes. After stirring, the mixture was filtered, washed, and dried to obtain modified metakaolin. The mass ratio of 6-hydroxymethylnicotinic acid, polyethylene glycol 200, polyethylene glycol 600, p-toluenesulfonic acid, and metakaolin is 175:450:450:0.9:1750. The D50 of the metakaolin is 4 μm.

[0019] The preparation method of the isobutyl methacrylate modified quartz sand is as follows: Sodium silicate was mixed with deionized water and stirred until completely dissolved to obtain a sodium silicate solution. Then, barium titanate was added to the sodium silicate solution and stirred until homogeneous to obtain a mixed solution. Quartz sand was added to the mixed solution and stirred at a controlled temperature of 45°C for 45 minutes. After stirring, a quartz sand slurry was obtained. Isobutyl methacrylate was added to the quartz sand slurry and stirred at a controlled temperature of 67°C for 65 minutes. After stirring, the quartz sand was filtered, washed, and dried to obtain modified quartz sand. The mass ratio of sodium silicate to deionized water is 7.0:100; The amount of barium titanate added is 20% of the total mass of sodium silicate; The mass ratio of the quartz sand to the mixed liquid is 2:2.5; The amount of isobutyl methacrylate added is 2.3% of the total mass of the quartz sand; The quartz sand is medium-grained quartz with a density of 2670 kg / m³. 3 .

[0020] The method for preparing the repair mortar is as follows: The specified mass of cement, isobutyl methacrylate modified quartz sand, and polyethylene glycol composite metakaolin in the raw material components are mixed and dry-mixed for 45 seconds. Then, water is added according to a water-cement ratio of 0.48. Next, the specified mass of styrene-butadiene latex, acrylic emulsion, defoamer, and water-reducing agent in the raw material components are added, and the mixture is stirred for another 330 seconds to obtain a polymer-modified cement pavement repair mortar.

[0021] Example 3 A polymer-modified cement pavement repair mortar, the raw material components of which include cement, isobutyl methacrylate modified quartz sand, polyethylene glycol composite metakaolin, styrene-butadiene latex, acrylic emulsion, defoamer, and water-reducing agent, with the mass ratio of each component being 115:320:55:55:32:1.1:1.1; The cement is PO42.5 ordinary Portland cement; The styrene-butadiene latex has a styrene to butadiene ratio of 40:60 and a solid content of 50 wt%. The acrylic emulsion is designated ADWEL1356, and its solid content is 50 wt%. The defoamer is model JT-930-J0408; The water-reducing agent is PCA-1 polycarboxylate water-reducing agent; The preparation method of the polyethylene glycol composite metakaolin is as follows: 6-Hydroxymethylnicotinic acid, polyethylene glycol 200, and polyethylene glycol 600 were mixed and stirred until homogeneous. Then, p-toluenesulfonic acid was added, and the mixture was stirred at 177°C under a nitrogen atmosphere for 110 minutes. Next, metakaolin was added, and the mixture was stirred at 177°C under a nitrogen atmosphere for 55 minutes. After stirring, the mixture was filtered, washed, and dried to obtain modified metakaolin. The mass ratio of 6-hydroxymethylnicotinic acid, polyethylene glycol 200, polyethylene glycol 600, p-toluenesulfonic acid, and metakaolin is 225:550:550:1.1:2250. The D50 of the metakaolin is 6 μm.

[0022] The preparation method of the isobutyl methacrylate modified quartz sand is as follows: Sodium silicate was mixed with deionized water and stirred until completely dissolved to obtain a sodium silicate solution. Then, barium titanate was added to the sodium silicate solution and stirred until homogeneous to obtain a mixed solution. Quartz sand was added to the mixed solution and stirred at a controlled temperature of 55°C for 25 minutes. After stirring, a quartz sand slurry was obtained. Isobutyl methacrylate was added to the quartz sand slurry and stirred at a controlled temperature of 75°C for 50 minutes. After stirring, the quartz sand was filtered, washed, and dried to obtain modified quartz sand. The mass ratio of sodium silicate to deionized water is 8.0:100; The amount of barium titanate added is 30% of the total mass of sodium silicate; The mass ratio of the quartz sand to the mixture is 2:3.5; The amount of isobutyl methacrylate added is 2.7% of the total mass of the quartz sand; The quartz sand is medium-grained quartz with a density of 2670 kg / m³. 3 .

[0023] The method for preparing the repair mortar is as follows: The specified mass of cement, isobutyl methacrylate modified quartz sand, and polyethylene glycol composite metakaolin in the raw material components are mixed and dry-mixed for 75 seconds. Then, water is added at a water-cement ratio of 0.52. Next, the specified mass of styrene-butadiene latex, acrylic emulsion, defoamer, and water-reducing agent in the raw material components are added. The mixture is stirred for another 280 seconds to obtain a polymer-modified cement pavement repair mortar.

[0024] Comparative Example 1 Unlike Example 1, in the raw materials of cement pavement repair mortar, untreated metakaolin is used instead of polyethylene glycol composite metakaolin as a raw material component while keeping the amount the same. The rest of the steps remain the same to prepare the repair material. The untreated metakaolin clay has a D50 of 5 μm.

[0025] Comparative Example 2 Unlike Example 1, in the raw materials of cement pavement repair mortar, untreated quartz sand is used instead of isobutyl methacrylate modified quartz sand as a raw material component while keeping the amount unchanged, and the rest of the steps remain the same to prepare the repair material. The untreated quartz sand is medium-grained quartz with a density of 2670 kg / m³. 3 .

[0026] Test Example 1: Compressive Strength Test The cement pavement repair mortars of Examples 1-3 and Comparative Examples 1-2 were used to prepare samples according to the method in DL / T5126-2021, and their compressive strength was tested. The results are shown in Table 1.

[0027] Table 1 Examples 1-3 use polyethylene glycol composite metakaolin as an active admixture and isobutyl methacrylate modified quartz sand as aggregate for repair mortar. Combined with cement, polymer and other components in the raw materials, polymer modified cement pavement repair mortar is prepared, which can effectively improve the compressive strength of the material. In Comparative Example 1, the use of untreated metakaolin instead of polyethylene glycol composite metakaolin as a raw material component in cement pavement repair mortar resulted in a certain degree of decrease in the compressive strength of the material. In Comparative Example 2, the use of untreated quartz sand instead of isobutyl methacrylate modified quartz sand as a raw material component in cement pavement repair mortar resulted in a significant decrease in the compressive strength of the material, with both the initial and later compressive strengths being low.

[0028] Test Example 2: Flexural Strength Test The cement pavement repair mortars of Examples 1-3 and Comparative Examples 1-2 were used to prepare samples according to the method in DL / T5126-2021, and their flexural strength was tested. The results are shown in Table 2.

[0029] Table 2 Examples 1-3 use polyethylene glycol composite metakaolin as an active admixture and isobutyl methacrylate modified quartz sand as aggregate for repair mortar. Combined with cement, polymer and other components in the raw materials, polymer-modified cement pavement repair mortar is prepared, which can effectively improve the flexural strength of the material. In Comparative Example 1, the use of untreated metakaolin instead of polyethylene glycol composite metakaolin as a raw material component in cement pavement repair mortar resulted in a certain degree of decrease in the flexural strength of the material. In Comparative Example 2, the use of untreated quartz sand instead of isobutyl methacrylate modified quartz sand as a raw material component in cement pavement repair mortar resulted in a significant decrease in the flexural strength of the material, and both the initial and later compressive strengths were low.

[0030] Test Example 3: Shear Bond Strength Test The cement pavement repair mortars of Examples 1-3 and Comparative Examples 1-2 were used to prepare samples according to the method in DL / T5126-2021, and their shear bond strength was tested. The results are shown in Table 3.

[0031] Table 3 Examples 1-3 use polyethylene glycol composite metakaolin as an active admixture and isobutyl methacrylate modified quartz sand as aggregate for repair mortar. Combined with cement, polymer and other components in the raw materials, polymer-modified cement pavement repair mortar is prepared, which can effectively improve the shear bond strength of the material. In Comparative Example 1, the use of untreated metakaolin instead of polyethylene glycol composite metakaolin as a raw material component in cement pavement repair mortar resulted in a significant decrease in the shear bond strength of the material, with both the initial and later shear bond strengths being low. In Comparative Example 2, using untreated quartz sand instead of isobutyl methacrylate modified quartz sand as a raw material component in cement pavement repair mortar resulted in a certain degree of decrease in the shear bond strength of the material.

[0032] Test Example 4: Flexural-Tension Bond Strength Test The cement pavement repair mortars of Examples 1-3 and Comparative Examples 1-2 were used to prepare samples according to the method in DL / T5126-2021, and their flexural bond strength was tested. The results are shown in Table 4.

[0033] Table 4 Examples 1-3 use polyethylene glycol composite metakaolin as an active admixture and isobutyl methacrylate modified quartz sand as aggregate for repair mortar. Combined with cement, polymer and other components in the raw materials, polymer-modified cement pavement repair mortar is prepared, which can effectively improve the flexural bond strength of the material. In Comparative Example 1, the use of untreated metakaolin instead of polyethylene glycol composite metakaolin as a raw material component in cement pavement repair mortar resulted in a significant decrease in the shear bond strength of the material, with both the initial and later flexural bond strengths being low. In Comparative Example 2, using untreated quartz sand instead of isobutyl methacrylate modified quartz sand as a raw material component in cement pavement repair mortar resulted in a certain degree of decrease in the flexural and tensile bond strength of the material.

[0034] Test Example 5 High Temperature Resistance Test Cement pavement repair mortars from Examples 1-3 and Comparative Examples 1-2 were used to prepare samples according to the method in DL / T5126-2021. The samples were cured under standard conditions for 28 days. After curing, the samples were heated to the specified temperature at a constant heating rate of 5℃ / min, which was set to 80℃ and 100℃ respectively. After reaching the specified temperature, the samples were kept at the specified temperature for 24 hours and then naturally cooled to room temperature. The residual compressive strength, residual flexural strength and mass loss of the samples were tested. The results are shown in Table 5.

[0035] Table 5 Examples 1-3 use polyethylene glycol composite metakaolin as an active admixture and isobutyl methacrylate modified quartz sand as aggregate for repair mortar. Combined with cement, polymer and other components in the raw materials, polymer-modified cement pavement repair mortar is prepared. This can effectively improve the high temperature resistance of the material. After being placed in a high temperature environment for a long time, the material can maintain high compressive strength and flexural strength, and the mass loss is small. In Comparative Example 1, the use of untreated metakaolin instead of polyethylene glycol composite metakaolin as a raw material component in cement pavement repair mortar resulted in a significant decrease in the material's high-temperature resistance, compressive strength, and flexural strength, as well as a significant loss in mass. In Comparative Example 2, the use of untreated quartz sand instead of isobutyl methacrylate modified quartz sand as a raw material component in cement pavement repair mortar resulted in a decrease in the material's high-temperature resistance, with a significant decrease in both compressive and flexural strength, as well as substantial mass loss.

Claims

1. A polymer-modified cementitious pavement repair mortar, characterized in that, The raw material components of the repair mortar include cement, isobutyl methacrylate modified quartz sand, polyethylene glycol composite metakaolin, styrene-butadiene rubber latex, acrylic emulsion, defoaming agent, water reducing agent; The preparation method of the polyethylene glycol composite metakaolin is: 6-hydroxymethyl nicotinic acid, polyethylene glycol 200, polyethylene glycol 600 are mixed and stirred to make them uniformly mixed, then p-toluenesulfonic acid is added, stirring is carried out under a nitrogen atmosphere, then metakaolin is added, the nitrogen atmosphere is maintained, and stirring is continued, after stirring is completed, filtration, washing and drying are carried out to obtain modified metakaolin; The preparation method of the isobutyl methacrylate modified quartz sand is: Sodium silicate is mixed with deionized water, and stirring is carried out to make it completely dissolved to obtain a sodium silicate solution, then barium titanate is added to the sodium silicate solution, and uniform stirring is continued, a mixed solution is obtained, quartz sand is added to the mixed solution for stirring, and after stirring is completed, a quartz sand slurry is obtained, isobutyl methacrylate is added to the quartz sand slurry for stirring, and after stirring is completed, the quartz sand is filtered, washed and dried to obtain modified quartz sand.

2. The polymer modified cement pavement repair mortar according to claim 1, characterized in that: In the raw material components of the repair mortar, the mass ratio of cement, isobutyl methacrylate modified quartz sand, polyethylene glycol composite metakaolin, styrene-butadiene rubber latex, acrylic emulsion, defoaming agent and water reducing agent is 85-115:250-320:45-55:45-55:28-32:0.9-1.1:0.9-1.1; The cement is PO42.5 ordinary portland cement; In the styrene-butadiene rubber latex, the ratio of styrene to butadiene is 40-60:40-60, and the solid content of the latex is 50wt%; The grade of the acrylic emulsion is ADWEL1356, and the solid content of the emulsion is 50wt%; The type of the defoaming agent is JT-930-J0408; The water reducing agent is PCA-1 polycarboxylic acid water reducing agent.

3. The polymer modified cement pavement repair mortar according to claim 1, characterized in that: In the preparation method of the polyethylene glycol composite metakaolin, after the addition of p-toluenesulfonic acid, stirring is carried out under a nitrogen atmosphere, and the temperature needs to be controlled at 170-177℃, and the stirring time is 110-125min; After the addition of metakaolin, stirring is continued under a nitrogen atmosphere, and the temperature needs to be controlled at 170-177℃, and the stirring time is 55-65min.

4. The polymer modified cement pavement repair mortar according to claim 1, characterized in that: In the preparation method of the polyethylene glycol composite metakaolin, the mass ratio of 6-hydroxymethyl nicotinic acid, polyethylene glycol 200, polyethylene glycol 600, p-toluenesulfonic acid and metakaolin is 175-225:450-550:450-550:0.9-1.1:1750-2250; The D50 of the metakaolin is 4-6μm.

5. The polymer modified cement pavement repair mortar according to claim 1, characterized in that: The preparation method of the methyl methacrylate modified quartz sand, the quartz sand is added into the mixed solution for stirring, the temperature needs to be controlled at 45-55 DEG C for stirring, and the stirring time is 25-45 min; After the isobutyl methacrylate is added into the quartz sand slurry, stirring is carried out, the temperature needs to be controlled at 67-75 DEG C, and the stirring time is 50-65 min.

6. The polymer modified cement pavement repairing mortar according to claim 1, characterized in that: In the preparation method of the methyl methacrylate modified quartz sand, the mass ratio of sodium silicate to deionized water is 7.0-8.0:100; The added amount of the barium titanate is 20-30% of the total mass of sodium silicate; The mass ratio of the quartz sand to the mixed solution is 2:2.5-3.5; The added amount of the isobutyl methacrylate is 2.3-2.7% of the total mass of the quartz sand; The quartz sand is medium sand quartz, with a density of 2670 kg / m 3 .

7. The preparation method of the polymer modified cement pavement repairing mortar according to claim 1, characterized in that: The preparation method of the repairing mortar is that the raw material components, i.e. cement, methyl methacrylate modified quartz sand and polyethylene glycol composite metakaolin with specified mass are mixed, dry mixing is carried out for 45-75 s, then water is added according to the water-cement ratio of 0.48-0.52, then butyl benzene latex, acrylic emulsion, defoaming agent and water reducing agent with specified mass are added, and the stirring is continuously carried out for 280-330 s, so as to obtain a polymer modified cement pavement repairing mortar.

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