A method for rapid repair of subgrade against road collapse risk

Abstract

The application relates to the technical field of road rapid repairing methods, in particular to a base rapid repairing method for road collapse risks, which comprises the following steps: firstly, constructing a gravel framework; secondly, preparing a cement-based grouting material; then, injecting the cement-based grouting material into the gravel framework; next, curing the structure after grouting; finally, performing surface treatment; the application realizes perfect balance between repairing quality and construction efficiency. Rapid construction of the gravel framework and rapid solidification of the high-performance grouting material enable the whole repairing process to be completed in a very short time, so that the influence on traffic is greatly reduced. Meanwhile, the high-strength characteristics of the composite structure ensure that the repairing quality is not affected by rapid construction.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of road rapid repair methods, and specifically relates to a base rapid repair method for road collapse risk. BACKGROUND

[0002] In recent years, with the rapid development of infrastructure construction and the acceleration of urbanization process in China, road collapse has become an increasingly serious problem. This not only affects traffic safety, but also brings great challenges to urban management. Traditional road collapse repair methods mainly include grouting reinforcement method, cement concrete slab reinforcement method and major repair and reconstruction method. However, these methods have some defects that are difficult to overcome in practical application.

[0003] Although the grouting reinforcement method is simple to operate, its repair effect is often unsatisfactory. This method is mainly suitable for slight base void repair, and its repair effect is often not ideal for serious structural damage. In addition, the bonding force between grouting material and original pavement material is limited, which is easy to cause secondary damage, resulting in non-durable repair effect.

[0004] The cement concrete slab reinforcement method can restore the pavement function in a short period of time, but it also has many problems. First of all, the combination between new and old materials is often not tight enough, which is easy to appear the phenomenon of wrong table and whole disengagement. Secondly, this method is often too high in cost for road sections with slight base disease, which does not conform to the principle of economic benefit. Finally, the shrinkage and cracking problem of concrete cannot be avoided, especially when large-area repair is carried out.

[0005] Although the major repair and reconstruction method can completely repair the base, its disadvantages are also very obvious. First of all, the construction period is long, which seriously affects the normal traffic order. Secondly, the engineering cost is high, which brings great pressure to local finance. Thirdly, large-scale excavation and reconstruction work will have a great impact on the surrounding environment, which does not conform to the current concept of green construction.

[0006] In the face of these problems, a rapid, efficient, economical and environmentally friendly road collapse repair method is urgently needed. The present application is an innovative solution to the problems of incomplete repair, long construction period and high construction cost in the prior art. SUMMARY

[0007] The technical problems to be solved by the present application mainly include: how to shorten the construction period while ensuring the repair quality; how to improve the overall performance of the repair structure, including strength, durability and anti-deformation ability; how to reduce the repair cost and the impact on the environment; and how to make the repair method have wide applicability and be able to cope with different degrees of collapse and various weather conditions.

[0008] To achieve the above object, the present application adopts the following technical solution: a method for quickly repairing base layer for road collapse risk, comprising the following steps: first, constructing a gravel framework; second, preparing a cement-based grouting material; then, injecting the cement-based grouting material into the gravel framework; next, curing the structure after grouting; finally, performing surface treatment.

[0009] Preferably, the construction of the gravel framework comprises using gravel with a particle size of 20-40 mm, and grading and laying according to the following weight ratio:

[0010] Gravel with a particle size of 20-25 mm: 30-40 parts by weight;

[0011] Gravel with a particle size of 25-30 mm: 30-40 parts by weight;

[0012] Gravel with a particle size of 30-40 mm: 20-40 parts by weight.

[0013] Preferably, the cement-based grouting material is composed of the following components, wherein the parts by weight of each component are based on the total amount of the grouting material 100 parts by weight:

[0014] Ordinary Portland cement with a label of P.O 42.5, 60-70 parts by weight;

[0015] Class F fly ash with a fineness not greater than 45 μm, 10-20 parts by weight;

[0016] Silica fume with a SiO2 content not less than 85% and a specific surface area not less than 15000 m2 / kg, 5-10 parts by weight;

[0017] Polycarboxylate high-performance water reducing agent, 0.5-1.5 parts by weight;

[0018] Polyether defoaming agent, 0.1-0.3 parts by weight;

[0019] Polypropylene fiber with a length of 6-12 mm and a diameter of 15-30 μm, 0.1-0.3 parts by weight;

[0020] Water, 25-30 parts by weight.

[0021] Preferably, the preparation method of the cement-based grouting material comprises the following steps:

[0022] First, dry mixing ordinary Portland cement, fly ash and silica fume for 2-3 minutes, wherein the rotation speed is 60-80 rpm;

[0023] Second, mix and uniformly stir the polycarboxylate high-performance water reducing agent with water;

[0024] Then, the above liquid is slowly added to the dry mixture and stirring is continued for 5-7 minutes while the speed is increased to 100-120 rpm;

[0025] Next, a polyether antifoaming agent is added and stirring is continued for 1-2 minutes;

[0026] Finally, polypropylene fibers are added and stirring is continued for 2-3 minutes to ensure uniform dispersion of the fibers.

[0027] Preferably, the specific steps of the grouting construction include:

[0028] The prepared grouting material is injected into the gravel skeleton using a high-pressure pump, wherein the grouting pressure is controlled at 0.2-0.5 MPa;

[0029] The grouting speed is controlled at 10-15 L / min;

[0030] An observation hole is set every 30-50 cm to monitor the grouting effect.

[0031] Preferably, the specific steps of the curing include: covering the repaired area with a plastic film; curing for 48-72 hours while maintaining the ambient temperature at 15-30℃ and the relative humidity at not less than 90%; and spraying water on the repaired area every 12 hours for curing.

[0032] Preferably, the specific steps of the surface treatment include: laying a 4-6 cm thick modified asphalt concrete surface layer; wherein the modified asphalt concrete surface layer has the following proportions, with the weight parts of each component based on 100 parts by weight of the total asphalt mixture:

[0033] SBS modified asphalt with a penetration of 60-80 and a softening point of not less than 75℃, 4.5-5.5 parts by weight;

[0034] Coarse aggregate with basalt material and a particle size of 9.5-19 mm, 50-60 parts by weight;

[0035] Fine aggregate with basalt material and a particle size of 0-9.5 mm, 35-45 parts by weight;

[0036] Mineral powder with limestone material and a particle size of less than 0.075 mm, 3-5 parts by weight.

[0037] Preferably, the laying step of the modified asphalt concrete surface layer includes:

[0038] The asphalt mixture paving temperature is controlled at 160-170℃;

[0039] The rolling temperature is ensured to be not less than 140℃;

[0040] The compaction is performed using a 12-ton double-steel-wheel road roller, and the number of compaction passes is not less than 6.

[0041] Preferably, the preparation method of the polycarboxylate-based high-performance water-reducing agent comprises:

[0042] First, 100 parts by weight of acrylic acid, 50-70 parts by weight of methyl allyl polyethylene glycol ether, and 200-300 parts by weight of deionized water are added to a four-necked flask;

[0043] Second, under nitrogen protection, the temperature is raised to 65-75°C, and the stirring speed is controlled at 300-400 rpm;

[0044] Then, 10-15 parts by weight of ammonium persulfate initiator solution with a concentration of 20wt% is slowly added dropwise;

[0045] Next, the reaction is carried out for 4-6 hours, and then cooled to room temperature;

[0046] Finally, the pH is adjusted to 6-7 with sodium hydroxide solution.

[0047] Preferably, the preparation method of the polyether-based defoaming agent comprises:

[0048] First, 100 parts by weight of ethylene oxide and 50-70 parts by weight of n-butanol are added to a reaction kettle;

[0049] Second, 0.5-1.0 parts by weight of potassium hydroxide is added as a catalyst;

[0050] Then, ring-opening polymerization is carried out at a temperature of 80-90°C and a pressure of 0.3-0.5 MPa;

[0051] Next, after the reaction is carried out for 6-8 hours, the temperature is cooled to room temperature, and unreacted ethylene oxide is removed by reduced pressure operation;

[0052] Finally, the catalyst is neutralized with phosphoric acid.

[0053] The present application forms a high-performance composite repair structure by innovatively combining the gravel skeleton with special formula grouting material. This structure not only solves various problems in traditional methods, but also brings many unexpected technical effects.

[0054] First, the present application realizes the perfect balance between repair quality and construction efficiency. The rapid construction of the gravel skeleton and the rapid solidification of the high-performance grouting material enable the entire repair process to be completed in a very short time, greatly reducing the impact on traffic. At the same time, the high-strength characteristics of the composite structure ensure that the repair quality will not be affected by rapid construction.

[0055] Secondly, the present application significantly improves the overall performance of the repaired structure. The gravel skeleton provides a stable load-bearing framework, while the special formula grout fills the gaps in the skeleton. The two work together to form a composite structure with high integrity and uniform stress distribution. This not only improves the strength and deformation resistance of the repaired structure, but also greatly enhances its durability.

[0056] Furthermore, the present application also performs well in terms of economy and environmental protection. Compared with major reconstruction, the present method significantly reduces material consumption and construction cost. At the same time, due to the absence of large-scale excavation, it greatly reduces the impact on the environment, in line with the concept of green construction.

[0057] Finally, the present application method has wide applicability. By adjusting the gravel gradation and grout formula, it can adapt to different degrees of collapse. Moreover, experimental results show that the method can maintain excellent performance under various climate conditions, which makes it can be widely applied nationwide.

[0058] In addition, the present application also exhibits some unexpected technical effects. For example, the repaired structure exhibits excellent interfacial bonding performance, which is due to the synergistic effect of the components in the special formula grout. In addition, long-term observation shows that the repaired structure also has a certain self-repairing ability, which is of great significance for prolonging the durability of the repair effect.

[0059] In summary, the present application not only solves the problems existing in the prior art, but also realizes performance breakthroughs in multiple aspects. It provides an innovative solution for the rapid, efficient and economical repair of road collapse, and has important practical application value and broad market prospects. DETAILED DESCRIPTION Example 1

[0060] This embodiment provides a method for rapid repair of the base layer against road collapse risk. The method realizes the rapid repair of the road base layer by constructing a gravel skeleton and injecting a cement-based grout with a specific ratio.

[0061] First, construct the gravel skeleton. Select granite gravel with a particle size of 20-40 mm, and grade it according to the following weight ratio: 20-25 mm particle size gravel 30 parts by weight, 25-30 mm particle size gravel 30 parts by weight, 30-40 mm particle size gravel 40 parts by weight. This grading method can optimize the void ratio of the skeleton and create good conditions for subsequent grouting.

[0062] Secondly, the cement-based grout is prepared. The grout is composed of the following components (based on 100 parts by weight of the total amount of the grout): ordinary Portland cement (P.O 42.5) 70 parts by weight, F-class fly ash (fineness 45 μm) 10 parts by weight, silica fume (SiO2 content 85%, specific surface area 15000 m2 / kg) 5 parts by weight, polycarboxylic acid-based high-performance water reducing agent 0.5 parts by weight, polyether-based defoaming agent 0.1 parts by weight, polypropylene fiber (length 6 mm, diameter 15 μm) 0.1 parts by weight, and water 25 parts by weight.

[0063] The method for preparing the cement-based grout comprises the following steps:

[0064] (1) First, the ordinary Portland cement, fly ash and silica fume are dry mixed for 2 minutes at a speed of 60 rpm;

[0065] (2) Secondly, the polycarboxylic acid-based high-performance water reducing agent is mixed with water and stirred uniformly;

[0066] (3) Then, the liquid in step (2) is slowly added to the dry mixed material in step (1), and the stirring is continued for 5 minutes at a speed of 100 rpm;

[0067] (4) Next, the polyether-based defoaming agent is added and stirred for 1 minute;

[0068] (5) Finally, the polypropylene fiber is added and stirred for 2 minutes to ensure uniform dispersion of the fiber.

[0069] Preferably, in the embodiments of the present application, the method for preparing the polycarboxylic acid-based high-performance water reducing agent comprises the following steps:

[0070] (a) 100 parts by weight of acrylic acid, 50 parts by weight of methyl allyl polyethylene glycol ether and 200 parts by weight of deionized water are added to a four-necked flask;

[0071] (b) Under nitrogen protection, the temperature is raised to 65°C and the stirring speed is 300 rpm;

[0072] (c) 10 parts by weight of ammonium persulfate initiator solution with a concentration of 20wt% is slowly added dropwise;

[0073] (d) The reaction is carried out for 4 hours and then cooled to room temperature;

[0074] (e) The pH is adjusted to 6 with sodium hydroxide solution.

[0075] The method for preparing the polyether-based defoaming agent comprises the following steps:

[0076] (a) 100 parts by weight of ethylene oxide and 50 parts by weight of n-butanol are added to a reaction kettle;

[0077] (b) adding 0.5 parts by weight of potassium hydroxide as catalyst;

[0078] (c) performing ring-opening polymerization at a temperature of 80°C and a pressure of 0.3 MPa;

[0079] (d) after 6 hours of reaction, cooling to room temperature, and removing unreacted ethylene oxide by a pressure reduction operation;

[0080] (e) neutralizing the catalyst with phosphoric acid.

[0081] Then, grouting construction is performed. The prepared grouting material is injected into the gravel framework using a high-pressure pump, with the grouting pressure controlled at 0.2 MPa and the grouting speed controlled at 10 L / min. An observation hole is set every 30 cm to monitor the grouting effect. This grouting method can ensure that the grouting material fills the gaps between the gravel and forms a stable overall composite structure.

[0082] Next, the grouted structure is cured. The repair area is covered with plastic film, and the curing time is 48 hours, during which the environmental temperature is maintained at 15°C and the relative humidity is 90%. The repair area is watered every 12 hours for curing. This curing method can ensure that the cement-based grouting material is fully hydrated and reaches the expected strength.

[0083] Finally, surface treatment is performed. A 4 cm thick modified asphalt concrete surface layer is laid, with the following proportions (based on 100 parts by weight of asphalt mixture): SBS modified asphalt (penetration 60, softening point 75°C) 4.5 parts by weight, coarse aggregate (basalt, particle size 9.5-19 mm) 60 parts by weight, fine aggregate (basalt, particle size 0-9.5 mm) 35 parts by weight, and mineral powder (limestone, particle size <0.075 mm) 3 parts by weight. The asphalt mixture is laid at a temperature of 160°C and rolled at a temperature of 140°C, using a 12-ton double steel wheel roller for rolling, with 6 passes. This surface treatment method can ensure the flatness and durability of the road surface. Example 2

[0084] This example provides another method for rapid repair of the base layer to address the risk of road collapse. Based on Example 1, some parameters are adjusted to adapt to different construction conditions.

[0085] First, the gravel framework is constructed. Limestone gravel with a particle size of 20-40 mm is selected, and graded and laid according to the following weight ratio: 20-25 mm particle size gravel 35 parts by weight, 25-30 mm particle size gravel 35 parts by weight, and 30-40 mm particle size gravel 30 parts by weight. This grading method can further optimize the framework structure and improve the overall stability.

[0086] Secondly, the cement-based grout was prepared. The grout was composed of the following components (based on 100 parts by weight of the total amount of the grout): ordinary Portland cement (P.O 42.5) 65 parts by weight, F-class fly ash (fineness 40 μm) 15 parts by weight, silica fume (SiO2 content 90%, specific surface area 17000 m2 / kg) 7 parts by weight, polycarboxylic acid-based high-performance water reducing agent 1 part by weight, polyether-based defoaming agent 0.2 parts by weight, polypropylene fiber (length 9 mm, diameter 20 μm) 0.2 parts by weight, and water 27 parts by weight.

[0087] The method for preparing the cement-based grout comprises the following steps:

[0088] (1) First, the ordinary Portland cement, fly ash and silica fume were dry mixed for 2.5 minutes at a speed of 70 rpm;

[0089] (2) Secondly, the polycarboxylic acid-based high-performance water reducing agent was mixed with water and stirred uniformly;

[0090] (3) Then, the liquid in step (2) was slowly added to the dry mixed material in step (1), and the stirring was continued for 6 minutes at a speed of 110 rpm;

[0091] (4) Next, the polyether-based defoaming agent was added, and stirred for 1.5 minutes;

[0092] (5) Finally, the polypropylene fiber was added, and stirred for 2.5 minutes to ensure uniform dispersion of the fiber.

[0093] In this embodiment, the method for preparing the polycarboxylic acid-based high-performance water reducing agent comprises the following steps:

[0094] (a) 100 parts by weight of acrylic acid, 60 parts by weight of methyl allyl polyethylene glycol ether and 250 parts by weight of deionized water were added to a four-necked flask;

[0095] (b) Under nitrogen protection, the temperature was raised to 70°C, and the stirring speed was 350 rpm;

[0096] (c) 12.5 parts by weight of ammonium persulfate initiator solution with a concentration of 20 wt% was slowly added dropwise;

[0097] (d) The reaction was carried out for 5 hours, and then the temperature was cooled to room temperature;

[0098] (e) The pH was adjusted to 6.5 with sodium hydroxide solution.

[0099] The method for preparing the polyether-based defoaming agent comprises the following steps:

[0100] (a) 100 parts by weight of ethylene oxide and 60 parts by weight of n-butanol were added to a reaction kettle;

[0101] (b) adding 0.75 parts by weight of potassium hydroxide as catalyst;

[0102] (c) performing ring-opening polymerization at a temperature of 85°C and a pressure of 0.4 MPa;

[0103] (d) after 7 hours of reaction, cooling to room temperature, and removing unreacted ethylene oxide by a pressure reduction operation;

[0104] (e) neutralizing the catalyst with phosphoric acid.

[0105] Then, the grouting operation is performed. The prepared grouting material is injected into the gravel framework using a high-pressure pump, with the grouting pressure controlled at 0.35 MPa and the grouting speed controlled at 12.5 L / min. An observation hole is set every 40 cm to monitor the grouting effect. This adjustment of grouting parameters can improve the grouting efficiency while ensuring the grouting quality.

[0106] Next, the structure after grouting is cured. The repair area is covered with plastic film, and the curing time is 60 hours, during which the environmental temperature is maintained at 22°C and the relative humidity is 95%. The repair area is watered every 12 hours for curing. Extending the curing time and increasing the humidity can further improve the repair strength.

[0107] Finally, the surface treatment is performed. A 5 cm thick modified asphalt concrete surface layer is laid, with the following ratio (based on 100 parts by weight of asphalt mixture): SBS modified asphalt (penetration 70, softening point 78°C) 5 parts by weight, coarse aggregate (basalt, particle size 9.5-19 mm) 55 parts by weight, fine aggregate (basalt, particle size 0-9.5 mm) 40 parts by weight, and mineral powder (limestone, particle size <0.075 mm) 4 parts by weight. The asphalt mixture paving temperature is controlled at 165°C, the rolling temperature is 145°C, the 12-ton double steel wheel roller is used for rolling, and the rolling is performed for 8 times. This adjustment can improve the anti-deformation ability and durability of the pavement. Example 3

[0108] This example provides a third method for rapid repair of the base layer against the risk of road collapse. This method further optimizes the material ratio and construction parameters for more severe collapse conditions.

[0109] First, the gravel framework is constructed. Granite gravel with a particle size of 20-40 mm is selected, and graded and laid according to the following weight ratio: 20-25 mm particle size gravel 40 parts by weight, 25-30 mm particle size gravel 40 parts by weight, and 30-40 mm particle size gravel 20 parts by weight. This grading method increases the proportion of small particle size gravel, which can improve the compactness of the framework.

[0110] Secondly, the cement-based grout was prepared. The grout was composed of the following components (based on 100 parts by weight of the total amount of the grout): ordinary Portland cement (P.O 42.5) 67 parts by weight, F-class fly ash (fineness 42 μm) 18 parts by weight, silica fume (SiO2content 88%, specific surface area 16000 m2 / kg) 8 parts by weight, polycarboxylic acid-based high-performance water reducing agent 1.2 parts by weight, polyether-based defoaming agent 0.25 parts by weight, polypropylene fiber (length 10 mm, diameter 25 μm) 0.25 parts by weight, and water 28 parts by weight.

[0111] The method for preparing the cement-based grout comprises the following steps:

[0112] (1) First, the ordinary Portland cement, fly ash and silica fume were dry mixed for 3 minutes at a speed of 75 rpm;

[0113] (2) Secondly, the polycarboxylic acid-based high-performance water reducing agent was mixed with water and stirred uniformly;

[0114] (3) Then, the liquid in step (2) was slowly added to the dry mixed material in step (1), and the stirring was continued for 6.5 minutes at a speed of 115 rpm;

[0115] (4) Next, the polyether-based defoaming agent was added and stirred for 1.8 minutes;

[0116] (5) Finally, the polypropylene fiber was added and stirred for 2.8 minutes to ensure uniform dispersion of the fiber.

[0117] In this embodiment, the method for preparing the polycarboxylic acid-based high-performance water reducing agent comprises the following steps:

[0118] (a) 100 parts by weight of acrylic acid, 65 parts by weight of methyl allyl polyethylene glycol ether and 275 parts by weight of deionized water were added to a four-necked flask;

[0119] (b) Under nitrogen protection, the temperature was raised to 72°C and the stirring speed was 375 rpm;

[0120] (c) 13.5 parts by weight of ammonium persulfate initiator solution with a concentration of 20 wt% was slowly added dropwise;

[0121] (d) The reaction was carried out for 5.5 hours and then cooled to room temperature;

[0122] (e) The pH was adjusted to 6.8 with sodium hydroxide solution.

[0123] The method for preparing the polyether-based defoaming agent comprises the following steps:

[0124] (a) 100 parts by weight of ethylene oxide and 65 parts by weight of n-butanol were added to a reaction kettle;

[0125] (b) adding 0.85 parts by weight of potassium hydroxide as catalyst;

[0126] (c) conducting ring-opening polymerization at a temperature of 87°C and a pressure of 0.45 MPa;

[0127] (d) after 7.5 hours of reaction, cooling to room temperature, and removing unreacted ethylene oxide by a reduced pressure operation;

[0128] (e) neutralizing the catalyst with phosphoric acid.

[0129] Then, the grouting operation is performed. The prepared grouting material is injected into the gravel framework using a high-pressure pump, with the grouting pressure controlled at 0.4 MPa and the grouting speed controlled at 13.5 L / min. An observation hole is set every 35 cm to monitor the grouting effect. The adjustment of such grouting parameters can further improve the grouting efficiency and filling degree, and is suitable for more serious collapse conditions.

[0130] Next, the structure after grouting is cured. The repair area is covered with plastic film, and the curing time is 66 hours, during which the environmental temperature is maintained at 25°C and the relative humidity is 98%. The repair area is watered every 12 hours for curing. The optimization of such curing conditions can promote the cement hydration reaction and improve the repair strength and durability.

[0131] Finally, the surface treatment is performed. A 5.5 cm thick modified asphalt concrete surface layer is laid, with the following ratio (based on 100 parts by weight of asphalt mixture): SBS modified asphalt (penetration 75, softening point 80°C) 5.2 parts by weight, coarse aggregate (basalt, particle size 9.5-19 mm) 52 parts by weight, fine aggregate (basalt, particle size 0-9.5 mm) 42 parts by weight, mineral powder (limestone, particle size <0.075 mm) 4.5 parts by weight. The asphalt mixture paving temperature is controlled at 168°C, the rolling temperature is 148°C, the 12-ton double steel wheel roller is used for rolling, and the rolling is 9 times. Such adjustment can further improve the anti-deformation ability, durability and anti-rutting performance of the pavement. Example 4

[0132] This example provides a fourth method for rapid repair of the base layer against the risk of road collapse. This method is suitable for road repair under special climate conditions, such as cold regions or high-temperature and rainy regions.

[0133] First, the gravel framework is constructed. Basalt gravel with a particle size of 20-40 mm is selected, and graded paving is performed according to the following weight ratio: 20-25 mm particle size gravel 38 parts by weight, 25-30 mm particle size gravel 38 parts by weight, and 30-40 mm particle size gravel 24 parts by weight. Such grading and material selection can improve the freeze-thaw resistance and overall stability of the framework.

[0134] Secondly, the cement-based grout was prepared. The grout was composed of the following components (based on 100 parts by weight of the total amount of the grout): ordinary Portland cement (P.O 42.5) 62 parts by weight, F-class fly ash (fineness 38 μm) 20 parts by weight, silica fume (SiO2content 92%, specific surface area 18000 m2 / kg) 10 parts by weight, polycarboxylic acid-based high-performance water reducing agent 1.5 parts by weight, polyether-based defoaming agent 0.3 parts by weight, polypropylene fiber (length 12 mm, diameter 30 μm) 0.3 parts by weight, and water 30 parts by weight.

[0135] The method for preparing the cement-based grout comprises the following steps:

[0136] (1) First, the ordinary Portland cement, fly ash, and silica fume were dry mixed for 3 minutes at a speed of 80 rpm;

[0137] (2) Secondly, the polycarboxylic acid-based high-performance water reducing agent was mixed with water and stirred uniformly;

[0138] (3) Then, the liquid in step (2) was slowly added to the dry mixed material in step (1), and the stirring was continued for 7 minutes at a speed of 120 rpm;

[0139] (4) Next, the polyether-based defoaming agent was added, and stirred for 2 minutes;

[0140] (5) Finally, the polypropylene fiber was added, and stirred for 3 minutes to ensure uniform dispersion of the fiber.

[0141] In this embodiment, the method for preparing the polycarboxylic acid-based high-performance water reducing agent comprises the following steps:

[0142] (a) 100 parts by weight of acrylic acid, 70 parts by weight of methyl allyl polyethylene glycol ether, and 300 parts by weight of deionized water were added to a four-necked flask;

[0143] (b) Under nitrogen protection, the temperature was raised to 75°C, and the stirring speed was 400 rpm;

[0144] (c) 15 parts by weight of ammonium persulfate initiator solution with a concentration of 20 wt% was slowly added dropwise;

[0145] (d) The reaction was carried out for 6 hours, and then the temperature was cooled to room temperature;

[0146] (e) The pH was adjusted to 7 with a sodium hydroxide solution.

[0147] The method for preparing the polyether-based defoaming agent comprises the following steps:

[0148] (a) 100 parts by weight of ethylene oxide and 70 parts by weight of n-butanol were added to a reaction kettle;

[0149] (b) adding 1.0 parts by weight of potassium hydroxide as a catalyst;

[0150] (c) conducting ring-opening polymerization at a temperature of 90°C and a pressure of 0.5 MPa;

[0151] (d) after 8 hours of reaction, cooling to room temperature, and removing unreacted ethylene oxide by a reduced pressure operation;

[0152] (e) neutralizing the catalyst with phosphoric acid.

[0153] Then, the grouting operation is performed. The prepared grouting material is injected into the gravel framework using a high-pressure pump, with the grouting pressure controlled at 0.5 MPa and the grouting speed controlled at 15 L / min. An observation hole is set every 50 cm to monitor the grouting effect. The adjustment of these grouting parameters ensures the sufficient penetration and filling of the grouting material under special weather conditions.

[0154] Next, the structure after grouting is cured. The repair area is covered with plastic film, and the curing time is 72 hours, during which the environmental temperature is maintained at 30°C (for high-temperature areas) or 10°C (for cold areas), and the relative humidity is 100%. The repair area is watered every 8 hours for curing. The adjustment of these curing conditions can adapt to different weather conditions, ensuring the full hydration of cement and achieving the expected strength.

[0155] Finally, the surface treatment is performed. A 6 cm thick modified asphalt concrete surface layer is laid, with the following proportions (based on 100 parts by weight of asphalt mixture): SBS modified asphalt (penetration 80, softening point 82°C) 5.5 parts by weight, coarse aggregate (basalt, particle size 9.5-19 mm) 50 parts by weight, fine aggregate (basalt, particle size 0-9.5 mm) 45 parts by weight, and mineral powder (limestone, particle size <0.075 mm) 5 parts by weight. The asphalt mixture is laid at a temperature of 170°C, and the rolling temperature is 150°C. A 12-ton double steel wheel roller is used for rolling, with 10 passes. This adjustment can improve the adaptability and durability of the pavement under extreme weather conditions.

[0156] It is worth noting that each component plays an important role in the entire repair process. For example, the polycarboxylate-based high-performance water-reducing agent disperses cement particles through electrostatic repulsion and steric hindrance, improving the fluidity of the grouting material, thereby ensuring that the grouting material can fully penetrate the pores of the gravel framework. The polyether-based defoamer eliminates bubbles by reducing surface tension, improving the density of the grouting material, and thereby enhancing the overall strength of the repaired structure. The addition of polypropylene fibers significantly improves the crack resistance and toughness of the repaired structure, helping to prevent cracking and damage of the pavement after repair.

[0157] This multi-component synergistic repair method not only quickly restores the load-bearing capacity of the road, but also provides excellent durability. By adjusting the proportions of each component and the preparation parameters, the present method can flexibly cope with different types and degrees of road collapse, providing an efficient, economical and adaptable solution for road maintenance and repair.

[0158] Comparative Example 1

[0159] This comparative example provides a traditional method for repairing road collapse, which is used for comparison with Example 1. This method only uses ordinary cement paste for grouting, without using gravel skeleton and composite grouting material.

[0160] First, prepare the ordinary cement paste. The paste is composed of the following components (based on 100 parts by weight of the total amount of the paste): ordinary Portland cement (P.O 42.5) 70 parts by weight, water 30 parts by weight.

[0161] The preparation method of the cement paste includes the following steps:

[0162] (1) Add ordinary Portland cement to the mixer;

[0163] (2) Slowly add water while stirring;

[0164] (3) Stir for 5 minutes at a speed of 60 rpm.

[0165] Then, grouting construction is carried out. The prepared cement paste is injected into the collapsed area using a conventional grouting pump, with the grouting pressure controlled at 0.2 MPa and the grouting speed controlled at 10 L / min.

[0166] Next, the structure after grouting is cured. The repair area is covered with plastic film, and the curing time is 48 hours, during which the environmental temperature is maintained at 20°C and the relative humidity is 85%.

[0167] Finally, surface treatment is carried out. A 4 cm thick ordinary asphalt concrete surface layer is laid, with the following ratio (based on 100 parts by weight of asphalt mixture): ordinary road petroleum asphalt (penetration 60, softening point 48°C) 5 parts by weight, coarse aggregate 55 parts by weight, fine aggregate 40 parts by weight. The asphalt mixture is laid at a temperature of 150°C, and the rolling temperature is 130°C. An 8-ton double steel wheel roller is used for rolling, with 6 passes.

[0168] Compared with Example 1, this comparative example lacks the synergistic effect of gravel skeleton and composite grouting material. This results in lower overall strength and stability of the repaired structure, and poor crack resistance. At the same time, due to the lack of use of high-performance water reducing agent and defoaming agent, the fluidity and compactness of the paste are poor, and the voids in the collapsed area cannot be fully filled. In addition, the anti-deformation ability and durability of the ordinary asphalt surface layer are not as good as those of the modified asphalt surface layer.

[0169] Comparative Example 2

[0170] This comparative example provides a road collapse repair method using only crushed stone filling, for comparison with Example 2. This method does not use grouting material, but relies entirely on crushed stone filling to restore the strength of the roadbed.

[0171] First, limestone crushed stone with a particle size of 20-40 mm is selected, and graded filling is performed according to the following weight ratio: 20-25 mm particle size crushed stone 35 parts by weight, 25-30 mm particle size crushed stone 35 parts by weight, and 30-40 mm particle size crushed stone 30 parts by weight.

[0172] The filling method includes the following steps:

[0173] (1) Pour the crushed stone into the collapsed area in layers;

[0174] (2) Each layer is about 20 cm thick, and a vibrating road roller is used for compaction;

[0175] (3) Repeat steps (1) and (2) until the collapsed area is filled.

[0176] Then, the filled structure is cured. The curing time is 24 hours, and the ambient temperature is maintained at 22°C and the relative humidity is 70% during the curing period.

[0177] Finally, surface treatment is performed. A 5 cm thick ordinary asphalt concrete surface layer is laid, with the same ratio as Comparative Example 1. The asphalt mixture is laid at a temperature of 155°C, and the rolling temperature is 135°C. A 10-ton double steel wheel roller is used for rolling, and the rolling is performed 7 times.

[0178] Compared with Example 2, although this comparative example uses graded crushed stone filling, the bonding strength between the crushed stones is low due to the lack of the binding effect of the grouting material. This leads to uneven settlement or loosening of the filled structure under long-term load. At the same time, due to the absence of cement-based grouting material, the overall strength and deformation resistance of the repaired structure are poor. In addition, the performance of the ordinary asphalt surface layer is not as good as the modified asphalt surface layer in Example 2.

[0179] Comparative Example 3

[0180] This comparative example provides a road collapse repair method using ordinary concrete pouring, for comparison with Example 3. This method does not use crushed stone framework and grouting material, but directly fills the collapsed area with concrete.

[0181] First, ordinary concrete is prepared. The concrete mix is as follows (based on 1 m³ of concrete):

[0182] Ordinary Portland cement (P.O 42.5) 350 kg, coarse aggregate (5-20 mm crushed stone) 1150 kg, fine aggregate (river sand) 750 kg, water 160 kg.

[0183] The method for preparing the concrete comprises the following steps:

[0184] (1) Add the coarse aggregate and fine aggregate into the mixer, and dry mix for 30 seconds;

[0185] (2) Add the cement, and continue to dry mix for 30 seconds;

[0186] (3) Add the water, and wet mix for 2 minutes.

[0187] Then, the concrete is poured. The prepared concrete is pumped to the collapsed area using a concrete pump, and is poured in layers with a thickness of about 30 cm. A plug-in vibrating rod is used for vibration to ensure that the concrete is fully compacted.

[0188] Next, the poured structure is cured. The curing time is 7 days, and the ambient temperature is maintained at 25°C and the relative humidity is 90% during the curing. The surface is kept wet by watering 3 times a day.

[0189] Finally, the surface is treated. A 5 cm thick ordinary asphalt concrete surface layer is laid, with the same ratio as Comparative Example 1. The asphalt mixture is laid at a temperature of 160°C, and is rolled at a temperature of 140°C using a 12-ton double steel wheel roller, and is rolled 8 times.

[0190] Compared with Example 3, the comparative example can provide higher strength, but has the following problems: first, the concrete has a high risk of shrinkage cracking, especially when repairing a large area. Second, the crack resistance and toughness of ordinary concrete are not as good as the composite structure in Example 3. Third, the concrete has a long curing time, which seriously affects the normal use of the road. Finally, the combination between the concrete structure and the original roadbed is not tight enough, and stress concentration is easy to occur, leading to cracking at the edge of the repaired area.

[0191] Comparative Example 4

[0192] The comparative example provides a method for repairing a road collapse by directly filling with modified asphalt mixture, which is used for comparison with Example 4. The method does not use crushed stone framework and grouting material, but directly fills the collapsed area with modified asphalt mixture.

[0193] First, the modified asphalt mixture is prepared. The ratio is as follows (based on 100 parts by weight of asphalt mixture):

[0194] SBS modified asphalt (penetration 70, softening point 76℃) 5.5 parts by weight, coarse aggregate (basalt, particle size 9.5-19mm) 50 parts by weight, fine aggregate (basalt, particle size 0-9.5mm) 44 parts by weight, mineral powder (limestone, particle size <0.075mm) 5 parts by weight.

[0195] The preparation method of the modified asphalt mixture comprises the following steps:

[0196] (1) heating the coarse aggregate and fine aggregate to 170℃;

[0197] (2) heating the SBS modified asphalt to 160℃;

[0198] (3) adding the heated aggregate, modified asphalt and mineral powder into an asphalt mixture stirrer and stirring for 3 minutes.

[0199] Then, the filling construction is carried out. The hot asphalt mixture is transported to the construction site and directly paved on the collapsed area using a paver. The paving is carried out in layers, and each layer has a thickness of about 8cm.

[0200] Next, a 12-ton double steel wheel roller is used for rolling, and the rolling temperature is controlled at 150℃, and the rolling is carried out for 9 times. The curing time is 24 hours, and vehicles are prohibited during the period.

[0201] Finally, a 4cm-thick modified asphalt concrete surface layer is laid on the surface of the filling layer, and the ratio is the same as that of the filling layer. The paving temperature is controlled at 165℃, the rolling temperature is 145℃, and the rolling is carried out for 8 times.

[0202] Compared with Example 4, although the high-performance modified asphalt mixture is used in this comparative example, there are still the following problems: first, the single asphalt mixture structure is prone to permanent deformation when bearing heavy traffic, resulting in rutting of the road surface. Second, the temperature sensitivity of the asphalt material is relatively high, and the performance will decrease significantly under extreme climate conditions (such as high temperature or low temperature environment). Third, the bonding strength between the asphalt mixture and the underlying roadbed is weak, resulting in interlayer separation. Finally, this method is difficult to effectively fill deep collapse, especially when the collapse depth is large.

[0203] Through the four comparative examples, the superiority of the method of the present application can be clearly seen. The present application adopts the combination of gravel skeleton and special grouting material, which fully utilizes the advantages of each component and forms a composite repair structure with high strength, high stability and high durability. This structure not only can quickly restore the bearing capacity of the road, but also has excellent anti-deformation and anti-cracking performance. At the same time, the construction speed of the method of the present application is fast, and the curing time is short, which greatly reduces the influence on traffic. These advantages can be reflected under different climate conditions and collapse depths, which reflects the wide applicability and high efficiency of the method of the present application.

[0204] To comprehensively evaluate the effectiveness and superiority of the "rapid base repair method for road collapse risk" of the present invention, a series of test experiments are designed. These experiments aim to verify the core innovation of the present invention, which is the performance of the composite repair structure combining the gravel framework with the special formula grouting material. The following is the detailed experimental design, method, results and analysis:

[0205] 1. Compressive strength test

[0206] Experimental method: According to GB / T 50081-2019 "Standard for Testing Methods of Mechanical Properties of Ordinary Concrete", cubic specimens of 100mm×100mm×100mm are prepared. Grouting material is injected into the pre-prepared gravel framework, and the compressive strength test is carried out after 28 days of curing.

[0207] Experimental steps:

[0208] First, place the specimen on the universal testing machine. Second, apply load uniformly at a rate of 0.5-0.8MPa / s. Then, record the maximum load at the time of specimen failure. Finally, calculate the compressive strength.

[0209] 2. Flexural strength test

[0210] Experimental method: According to GB / T 50081-2019, prism specimens of 100mm×100mm×400mm are prepared. Three-point bending test is carried out after 28 days of curing.

[0211] Experimental steps:

[0212] First, place the specimen on the flexural testing machine with a support point spacing of 300mm. Second, apply load uniformly at a rate of 0.05MPa / s. Then, record the maximum load at the time of specimen failure. Finally, calculate the flexural strength.

[0213] 3. Shrinkage test

[0214] Experimental method: According to GB / T 50082-2009 "Standard for Testing Methods of Long-term Performance and Durability of Ordinary Concrete", prism specimens of 100mm×100mm×515mm are prepared, and measuring heads are embedded at both ends.

[0215] Experimental steps:

[0216] First, measure the initial length immediately after demolding. Second, place the specimen in a standard curing room (temperature 20±2℃, relative humidity 60±5%). Then, measure the length at 1d, 3d, 7d, 14d, 28d, 56d, 90d. Finally, calculate the shrinkage at each age.

[0217] 4. Impermeability test

[0218] Experimental method: According to GB / T 50082-2009, Φ150mm x 150mm cylindrical test pieces were prepared. After 28 days of curing, the impermeability test was performed.

[0219] Experimental steps:

[0220] First, the test piece was installed on the impermeability instrument. Second, the pressure was gradually increased at a rate of 0.1 MPa / h, and each level of pressure was maintained for 8 h. Then, when the water pressure reached 1.2 MPa, it was maintained for 72 h. Finally, the test piece was split, and the water penetration depth was measured.

[0221] 5. Freeze-thaw resistance test

[0222] Experimental method: According to GB / T 50082-2009, 100mm x 100mm x 400mm prismatic test pieces were prepared. After 28 days of curing, the freeze-thaw cycle test was performed.

[0223] Experimental steps:

[0224] First, the test piece was immersed in water for 24 h. Second, the freeze-thaw cycle was performed (-18℃ ~ 5℃, 4h per cycle). Then, the relative dynamic elastic modulus was measured after every 25 cycles. Finally, the test was stopped after 300 cycles or when the relative dynamic elastic modulus was less than 60%.

[0225] The test results are as follows:

[0226] Table 1: Compressive strength, flexural strength and 28-day shrinkage of each test piece

[0227]

[0228] Table 2: Impermeability and freeze-thaw resistance of each test piece

[0229]

[0230] The results are analyzed as follows:

[0231] 1. Mechanical properties: As can be seen from Table 1, Examples 1-4 of the present application all exhibit excellent compressive strength and flexural strength. In particular, Example 3 has a compressive strength of 52.7 MPa and a flexural strength of 6.7 MPa, far exceeding all the comparative examples. This proves that the composite structure of the gravel skeleton combined with the special formula grouting material has significant mechanical performance advantages.

[0232] 2. Shrinkage performance: The 28-day shrinkage of Examples 1-4 of the present application is significantly lower than that of Comparative Examples 1 and 3. This indicates that the method of the present application can effectively control the shrinkage of the repaired structure, reducing the risk of cracking. It is worth noting that Comparative Examples 2 and 4 are not suitable for shrinkage testing as they do not contain cement-based materials.

[0233] 3. Impermeability performance: Examples 1-4 all achieve an impermeability rating of P10 or higher, while the impermeability ratings of the comparative examples are generally lower. This shows that the composite structure formed by the method of the present application has excellent compactness and impermeability, which is beneficial to improving the durability of the repaired structure.

[0234] 4. Freeze-thaw resistance performance: After 300 freeze-thaw cycles, the relative dynamic elastic modulus of Examples 1-4 remains above 92%, which is much higher than that of the comparative examples. This indicates that the repaired structure formed by the method of the present application has excellent freeze-thaw resistance performance and is suitable for road repair in cold regions.

[0235] Based on the above test results, Example 3 can be considered the best example. It performs the most outstanding in terms of mechanical properties, shrinkage control, impermeability, and freeze-thaw resistance.

[0236] The present application has the following unexpected technical effects:

[0237] 1. Ultra-high early strength: Although the test results show the 28-day strength, it is found in actual application that the repaired structure formed by the method of the present application can reach a strength sufficient to withstand normal traffic loads within 3 days. This greatly shortens the curing time of road repair and reduces traffic disruption.

[0238] 2. Excellent interfacial bonding performance: It is found during testing that the composite structure formed by the method of the present application has extremely high bonding strength with the original roadbed material. This is due to the synergistic effect of ultra-fine silica fume and high-performance water-reducing agent in the special formula grouting material, which improves the flowability and adhesion of the grouting material.

[0239] 3. Self-repairing ability: Long-term observation shows that the repaired structure formed by the method of the present application has a certain self-repairing ability. This is because the unhydrated cement particles in the grouting material continue to hydrate when micro-cracks appear, thereby filling the cracks.

[0240] 4. Excellent fatigue resistance: Although this test does not include fatigue performance testing, it is observed in actual application that the road section repaired by the method of the present application has minimal deformation under long-term repeated loads. This is because the gravel skeleton provides a stable support structure, and the special formula grouting material fills the gaps in the skeleton, forming a composite structure with high integrity and uniform stress distribution.

[0241] 5. Environmental adaptability: Test results show that the method of the present application not only performs excellently at room temperature, but also maintains good performance in high-temperature and low-temperature environments. This full-temperature-domain adaptability enables the method of the present application to be widely applied to road repair in different climate regions.

[0242] In summary, the method of the present application realizes rapid and high-strength road repair through the innovative combination of the gravel framework and the special formula grouting material, and also performs excellently in terms of durability, environmental adaptability, etc. These excellent performances and unexpected technical effects enable the method of the present application to have important application prospects in the field of road maintenance and repair.

[0243] The above description is only the preferred embodiments of the present application, and does not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made by using the content of the present application specification, or direct or indirect application in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A method for rapid repair of a base course against the risk of road collapse, characterized in that, The method comprises the following steps: Firstly, constructing a gravel framework; Secondly, preparing a cement-based grouting material; Then, injecting the cement-based grouting material into the gravel framework; subsequently, curing the grouted structure; finally, performing surface treatment; The cement-based grouting material is composed of the following components, wherein the weight parts of each component are based on the total amount of the grouting material 100 parts by weight: Ordinary Portland cement with a label of P.O 42.5, 60-70 parts by weight; Fly ash of type F with a fineness not greater than 45 μm, 10-20 parts by weight; Silica fume with a SiO2 content not less than 85% and a specific surface area not less than 15000 m² / kg, 5-10 parts by weight; Polycarboxylate high-performance water-reducing agent, 0.5-1.5 parts by weight; Polyether antifoaming agent, 0.1-0.3 parts by weight; Polypropylene fiber with a length of 6-12 mm and a diameter of 15-30 μm, 0.1-0.3 parts by weight; Water, 25-30 parts by weight; The preparation method of the polyether antifoaming agent comprises the following steps: Firstly, adding 100 parts by weight of ethylene oxide and 50-70 parts by weight of n-butanol into a reaction kettle; Secondly, adding 0.5-1.0 parts by weight of potassium hydroxide as a catalyst; Then, performing ring-opening polymerization reaction at a temperature of 80-90 °C and a pressure of 0.3-0.5 MPa; Subsequently, after 6-8 hours of reaction, cooling to room temperature, and removing unreacted ethylene oxide by pressure reduction operation; Finally, neutralizing the catalyst with phosphoric acid.

2. The method of claim 1, wherein, The construction of the gravel framework comprises using gravel with a particle size of 20-40 mm, and grading laying according to the following weight ratio: Gravel with a particle size of 20-25 mm: 30-40 parts by weight; Gravel with a particle size of 25-30 mm: 30-40 parts by weight; Gravel with a particle size of 30-40 mm: 20-40 parts by weight.

3. The method of claim 1, wherein, The preparation method of the cement-based grouting material comprises the following steps: Firstly, dry mixing ordinary Portland cement, fly ash and silica fume for 2-3 minutes, wherein the rotating speed is 60-80 rpm; Secondly, mixing and uniformly stirring the polycarboxylate high-performance water-reducing agent with water; Then, slowly adding the above-mentioned liquid into the dry mixed material, and continuing to stir for 5-7 minutes while increasing the rotating speed to 100-120 rpm; Subsequently, adding the polyether antifoaming agent, and stirring for 1-2 minutes; Finally, adding the polypropylene fiber, and stirring for 2-3 minutes to ensure uniform dispersion of the fiber.

4. The method of claim 1, wherein, The specific steps of grouting construction comprise: Using a high-pressure pump to inject the prepared grouting material into the gravel framework, wherein the grouting pressure is controlled at 0.2-0.5 MPa; Controlling the grouting speed at 10-15 L / min; Setting an observation hole every 30-50 cm for monitoring the grouting effect.

5. The method of claim 1, wherein, The specific steps of curing comprise: covering the repaired area with plastic film; curing for 48-72 hours, during which the environmental temperature is maintained at 15-30 °C, and the relative humidity is not less than 90%; and performing water spraying curing on the repaired area every 12 hours.

6. The method of claim 1, wherein, The specific steps of the surface treatment include: laying a 4-6 cm thick modified asphalt concrete surface layer; wherein the modified asphalt concrete surface layer has the following proportions, the weight parts of each component being based on 100 parts by weight of the total amount of asphalt mixture: SBS modified asphalt with a penetration of 60-80 and a softening point not less than 75℃, 4.5-5.5 parts by weight; Coarse aggregate with basalt material and a particle size of 9.5-19 mm, 50-60 parts by weight; Fine aggregate with basalt material and a particle size of 0-9.5 mm, 35-45 parts by weight; Mineral powder with limestone material and a particle size less than 0.075 mm, 3-5 parts by weight.

7. The method of claim 6, wherein, The laying step of the modified asphalt concrete surface layer includes: Controlling the asphalt mixture paving temperature at 160-170℃; Ensuring that the rolling temperature is not less than 140℃; Using a 12-ton double steel wheel roller for rolling, wherein the rolling passes are not less than 6 times.

8. The method of claim 1, wherein, The preparation method of the polycarboxylic acid high-performance water reducing agent includes: First, add 100 parts by weight of acrylic acid, 50-70 parts by weight of methyl allyl polyethylene glycol ether and 200-300 parts by weight of deionized water into a four-necked flask; Second, under nitrogen protection, heat to 65-75℃, and control the stirring speed at 300-400 rpm; Then, slowly add 10-15 parts by weight of ammonium persulfate initiator solution with a concentration of 20wt%; Next, react for 4-6 hours, and then cool to room temperature; Finally, adjust the pH to 6-7 with sodium hydroxide solution.

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