Rapid repairing material for bridge expansion joint notch concrete as well as preparation method and application of rapid repairing material

Abstract

The invention relates to the technical field of building materials, in particular to a bridge expansion joint notch concrete rapid repairing material and a preparation method and application thereof. The repairing material is composed of raw materials in a specific proportion, cement is formed by compounding silicate and quick-hardening sulphoaluminate, silica fume with a high specific surface area, machine-made sand, crystal nucleus type early strength agent powder, steel fibers, a calcium aluminate expanding agent, sodium gluconate and self-made polycarboxylic acid water reducing agent powder are matched, and all the components have a synergistic effect. The repairing material provided by the invention has outstanding ultra-early strength, can quickly recover the bearing capacity of the expansion joint, effectively deals with complex working conditions such as vehicle impact, temperature change and erosion, has strong cohesiveness and good impact and deformation resistance, makes up the defects of the traditional material, greatly shortens the traffic interruption time, has great significance in guaranteeing the safe operation of the bridge and improving the durability, and has wide application prospects. The method is suitable for bridge expansion joint concrete rapid repair engineering.

Description

Technical Field

[0001] The present invention relates to the technical field of building materials, and particularly relates to a rapid repair material for concrete in the expansion joint groove of a bridge, its preparation method and application. Background Art

[0002] As an important part of the bridge structure, the bridge expansion joint plays an indispensable role in adapting to the deformation of the bridge caused by factors such as temperature change, vehicle load, and concrete shrinkage and creep. Its performance directly affects the overall stability of the bridge and driving safety. In recent years, with the booming development of the transportation industry, the traffic flow has shown a sharp increase. Coupled with the continuous increase in vehicle load, the stress and deformation cycle times borne by the bridge expansion joint have increased significantly, and the early damage phenomenon has become more prominent, becoming one of the high-incidence areas of bridge diseases.

[0003] Common diseases of the concrete in the transition area of the bridge expansion joint include various types such as concrete fracture, net cracking, spalling, and debonding from the main bridge structure and the bridge deck asphalt concrete pavement layer. Concrete fracture is usually caused by the fatigue stress generated by long-term exposure to vehicle impact loads and repeated expansion and contraction deformations. Once cracks appear, they will rapidly expand under the action of moisture and corrosive media, severely weakening the structural strength of the expansion joint. Net cracking is mostly due to unreasonable concrete mix ratio, poor construction quality or improper maintenance, resulting in insufficient tensile strength on the concrete surface, and forming a fine crack network under the combined action of temperature change and vehicle load, which not only affects the appearance but also reduces the durability of the concrete. The spalling phenomenon is mainly due to the degradation of the adhesion between the concrete and the steel bars. Under the influence of environmental factors such as water flow scouring and freeze-thaw cycles, the concrete surface gradually loosens and peels off, further endangering the normal function of the expansion joint. The debonding of the concrete from the surrounding structure will damage the integrity of the expansion joint, resulting in its inability to effectively transfer loads and adapt to deformations, and exacerbating the degree of structural damage.

[0004] In the repair project of local damage of expansion joints, the current technical materials and methods have many shortcomings. The strength of traditional repair materials develops slowly and the ultra-early strength is low. It is difficult to form sufficient bearing capacity in a short time to meet the requirements of rapid construction and traffic opening, which makes traffic congestion serious during the repair process and causes huge economic losses. The working environment of the road-bridge connection where the expansion joint is located is complex and harsh. It not only has to withstand frequent impacts and dynamic loads of vehicles, but also has to withstand the test of rainwater erosion, temperature changes, chemical corrosion and other factors. Therefore, the repair material needs to have good adhesion with the expansion joint anchor bar and the old concrete to ensure that the repaired structure works together; at the same time, it also needs to have excellent impact resistance and deformation ability to prevent damage again during subsequent use. However, the commonly used concrete materials currently perform generally in terms of adhesion, and are prone to impact deformation and fracture damage under complex stress environments, which cannot effectively meet the special requirements of expansion joint repair. Although steel fiber concrete can improve the toughness and impact resistance of concrete to a certain extent, due to its long curing time, it requires long-term traffic closure, which is obviously not feasible in busy traffic sections, greatly limiting its application in rapid repair projects.

[0005] In summary, traditional expansion joint repair materials are far from meeting the urgent needs of modern traffic for rapid bridge repair. In order to ensure the safe operation of bridges and reduce traffic interruption time, it is urgent to carry out in-depth research and innovation on ultra-early strength and high-performance expansion joint repair materials to effectively solve the problem of rapid repair of damaged expansion joint surfaces and improve the durability and service level of bridges. Summary of the invention

[0006] The present invention aims to solve the problems in the above-mentioned background technology. A bridge expansion joint notch concrete quick repair material is characterized in that it is composed of the following raw materials in parts by weight: 850-900 parts of cement, 95-100 parts of silica fume, 790-800 parts of machine-made sand, 10-15 parts of early strength agent, 75-80 parts of steel fiber, 25-30 parts of expansion agent, 200-205 parts of water, 1.5-2 parts of sodium gluconate, and 15-20 parts of polycarboxylate water-reducing agent powder; On the basis of the above technical scheme, further, calculated by weight, the polycarboxylic acid water-reducing agent powder is composed of 100-150 parts of methoxy polyethylene glycol ether acrylate, 18-32 parts of acrylic acid, 4-10 parts of thioglycolic acid, a pH adjusting agent, and 0.7%-5% of hydrogen peroxide based on the mass fraction of the total raw materials.

[0007] On the basis of the above technical solution, further, the preparation method of the polycarboxylate water-reducing agent powder is: In the reaction kettle, add pure water and methoxy polyethylene glycol ether acrylate in sequence and heat to 70°C; Add acrylic acid, thioglycolic acid, and hydrogen peroxide dropwise within 4 hours. After the dropwise addition is completed, carry out a heat preservation reaction; Cool down to 40 - 50 °C and neutralize with a pH adjusting reagent to a pH value of 7.0 to obtain a polycarboxylate superplasticizer mother liquor; Carry out pneumatic spray drying treatment on the mother liquor to obtain a solid superplasticizer; Ball mill and screen the solid to obtain the polycarboxylate superplasticizer powder.

[0008] Based on the above technical solution, further, it is composed of the following raw materials in parts by weight: 869 parts of cement, 97 parts of silica fume, 798 parts of manufactured sand, 14 parts of early strength agent, 78 parts of steel fiber, 29 parts of expansion agent, 203 parts of water, 1.9 parts of sodium gluconate, and 19.3 parts of polycarboxylate superplasticizer powder.

[0009] Based on the above technical solution, further, the cement is composed of Portland cement and rapid hardening sulphoaluminate cement in a weight ratio of 255 - 260:300 - 610.

[0010] Based on the above technical solution, further, the specific surface area of the silica fume is 22000 - 22500 kg / m 2 .

[0011] Based on the above technical solution, further, the early strength agent is a crystal nucleus type early strength agent powder.

[0012] Based on the above technical solution, further, the expansion agent is a calcium aluminate expansion agent.

[0013] The present invention also provides a preparation method of the rapid repair material for the concrete of the bridge expansion joint notch as described above, including the following steps: Weigh cement, silica fume, manufactured sand, early strength agent, sodium gluconate, steel fiber, expansion agent, polycarboxylate superplasticizer powder, and water according to the proportion; Pour the above powder materials into a mixing pan for premixing, add water and stir, and slowly add steel fiber and stir until the target fluidity is reached; Pour out the stirred repair material for molding; Demold after a period of time, and obtain the rapid repair material for the concrete of the bridge expansion joint notch after reaching the predetermined age.

[0014] The present invention also provides an application of the rapid repair material for the concrete of the bridge expansion joint notch as described above in concrete construction.

[0015] The technical solution of the present invention has the following principles and beneficial effects: The rapid repair material for the concrete of the bridge expansion joint groove provided by the present invention realizes its ultra-early high strength, good fluidity and dispersion performance through the careful design of the raw material composition and ratio. The unique cement combination and the synergistic effect of each raw material enable the repair material to have far higher ultra-early strength than traditional materials, and can quickly restore the bearing function of the expansion joint. For example, it can reach the traffic opening strength requirement within the specified time, reduce the traffic control time, and ensure the safe and efficient operation of the bridge. Among them, preferably, Portland cement and rapid hardening sulphoaluminate cement are compounded, and the characteristics of the two are used synergistically to improve the early strength. Silica fume with a high specific surface area is designed to enhance filling and reaction activity, and manufactured sand provides a stable skeleton structure. Early strength agents are used to accelerate the cement hydration process, and the powder of crystal nucleus type early strength agent has a significant effect. Steel fibers enhance toughness and impact resistance, and calcium aluminate expansive agent compensates for shrinkage and prevents cracking.

[0016] Preferably, the polycarboxylate superplasticizer powder of the present invention, through specific raw materials and preparation processes, has characteristics that enable the repair material to be evenly mixed during stirring, with good cement dispersion, good fluidity, and self-leveling characteristics, which can fully fill the damaged area, reduce the stirring and construction time, improve the repair efficiency, adapt to the urgent rhythm of rapid repair projects, reduce the construction difficulty and cost, and ensure the repair quality. However, the premature strength also shortens the setting time accordingly, which is not conducive to construction operations. The present invention uses sodium gluconate with a specific ratio to delay the setting time of the repair material, so that the initial setting time exceeds 30 minutes, providing a window for construction. Specific embodiments

[0017] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0018] The present invention provides the following examples and comparative examples of the rapid repair material for the concrete of the bridge expansion joint groove: Example 1 Raw material composition: 869 parts of cement (including 261 parts of Conch 525 ordinary Portland cement and 608 parts of Shili rapid hardening sulphoaluminate cement), 97 parts of silica fume (specific surface area 22000 kg / m²), 798 parts of manufactured sand, 14 parts of early strength agent (powder of crystal nucleus type early strength agent), 78 parts of steel fibers (copper-plated end-hooked steel fibers, length 13 mm, diameter 0.32 mm), 29 parts of expansive agent (calcium aluminate expansive agent), 203 parts of water, 1.9 parts of sodium gluconate, and 19.3 parts of polycarboxylate superplasticizer powder.

[0019] Preparation of polycarboxylate water reducer powder: 120 parts of methoxypolyethylene glycol ether acrylate, 25 parts of acrylic acid, 5 parts of mercaptoacetic acid, and hydrogen peroxide accounting for 3% of the total raw material mass fraction. In the reaction kettle, first add pure water and methoxypolyethylene glycol ether acrylate and heat up to 70°C. Dropwise add acrylic acid, mercaptoacetic acid, and hydrogen peroxide within 4 hours, keep the temperature for 3 hours for reaction, cool down to 50°C, and neutralize with a 40% sodium hydroxide solution to a pH value of 7.0 to obtain the polycarboxylate water reducer mother liquor, which is then obtained as powder through pneumatic spray drying, ball milling, and screening.

[0020] Preparation method of rapid repair material for concrete in bridge expansion joint slot: Weigh the raw materials in proportion, pour the powder into the mixing pot for premixing for 1.5 min, add water and stir for 4 min, slowly add steel fiber and stir for 2 min until the target fluidity is reached, pour out and mold, demold after a period of time, and obtain the repair material after reaching the predetermined age.

[0021] Example 2 Raw material composition: 875 parts of cement (including 270 parts of portland cement and 605 parts of rapid hardening sulphoaluminate cement), 98 parts of silica fume (specific surface area 22000 kg / m²), 795 parts of manufactured sand, 13 parts of early strength agent (nucleating type early strength agent powder), 77 parts of steel fiber (copper-plated end-hooked steel fiber, length 13 mm, diameter 0.32 mm), 28 parts of expansive agent (calcium aluminate expansive agent), 202 parts of water, 1.8 parts of sodium gluconate, 18 parts of polycarboxylate water reducer powder.

[0022] Preparation of polycarboxylate water reducer powder: 130 parts of methoxypolyethylene glycol ether acrylate, 28 parts of acrylic acid, 6 parts of mercaptoacetic acid, and hydrogen peroxide accounting for 4% of the total raw material mass fraction. In the reaction kettle, first add pure water and methoxypolyethylene glycol ether acrylate and heat up to 70°C. Dropwise add acrylic acid, mercaptoacetic acid, and hydrogen peroxide within 4 hours, keep the temperature for three hours for reaction, cool down to 50°C, and neutralize with a 40% sodium hydroxide solution to a pH value of 7.0 to obtain the polycarboxylate water reducer mother liquor, which is then obtained as powder through pneumatic spray drying, ball milling, and screening.

[0023] Preparation method of rapid repair material for concrete in bridge expansion joint slot: The same as Example 1.

[0024] Example 3 Raw material composition: 880 parts of cement (265 parts of portland cement, 615 parts of rapid hardening sulphoaluminate cement), 96 parts of silica fume (specific surface area 22000 kg / m²), 796 parts of manufactured sand, 12 parts of early strength agent (nucleating type early strength agent powder), 76 parts of steel fiber (copper-plated end-hooked steel fiber, length 12.5 mm, diameter 0.31 mm), 27 parts of expansion agent (calcium aluminate expansion agent), 204 parts of water, 1.7 parts of sodium gluconate, 17 parts of polycarboxylate superplasticizer powder.

[0025] Preparation of polycarboxylate superplasticizer powder: 140 parts of methoxypolyethylene glycol ether acrylate, 30 parts of acrylic acid, 7 parts of mercaptoacetic acid, 3.5% of hydrogen peroxide by total raw material mass fraction. The preparation process is the same as that in Example 1.

[0026] Preparation method of rapid repair material for bridge expansion joint slot concrete: The same as that in Example 1.

[0027] Comparative Example 1 All use 869 parts of ordinary portland cement, 97 parts of silica fume (specific surface area 22000 kg / m²), 798 parts of manufactured sand, 14 parts of early strength agent (nucleating type early strength agent powder), 78 parts of steel fiber (copper-plated end-hooked steel fiber, length 12 mm, diameter 0.3 mm), 29 parts of expansion agent (calcium aluminate expansion agent), 203 parts of water, 1.9 parts of sodium gluconate, 19.3 parts of polycarboxylate superplasticizer powder. The preparation of polycarboxylate superplasticizer powder and the preparation method of the repair material are the same as those in Example 1.

[0028] Comparative Example 2 In terms of raw material composition: The raw material of polycarboxylate superplasticizer powder is removed, and the dosage and type of the remaining raw materials are the same as those in Example 1. The preparation of polycarboxylate superplasticizer powder and the preparation method of the repair material are the same as those in Example 1.

[0029] Comparative Example 3 In terms of raw material composition: The polycarboxylate superplasticizer powder is replaced with other polycarboxylate superplasticizers. The difference between the other polycarboxylate superplasticizer and the polycarboxylate superplasticizer powder of the present invention in components is that acrylic acid is replaced with styrene sulfonic acid.

[0030] The dosage and type of the remaining raw materials are the same as those in Example 1. The preparation of polycarboxylate superplasticizer powder and the preparation method of the repair material are the same as those in Example 1.

[0031] Comparative Example 4 In terms of raw material composition: Sodium gluconate is not added. The dosage and type of the remaining raw materials are the same as those in Example 1. The preparation of polycarboxylate superplasticizer powder and the preparation method of the repair material are the same as those in Example 1.

[0032] The examples and comparative examples prepared by the present invention were subjected to the following tests, and the test standards (methods) were: "Standard Test Methods for Properties of Ordinary Concrete Mixtures" (GB / T 50080-2016); the test results are shown in the following table Table 1

[0033] It can be seen from the systematic tests and comparative analyses of the above examples and comparative examples that: In terms of setting time, in Examples 1-3, with the help of a specific raw material combination and ratio, especially the synergistic effect of polycarboxylate superplasticizer powder and sodium gluconate, the initial setting time was successfully controlled within the appropriate range of 35-37 minutes. In contrast, in Comparative Example 1 where all ordinary Portland cement was used, the setting time was as long as 320 minutes, seriously affecting the construction efficiency; in Comparative Example 4 where sodium gluconate was not added, the initial setting time was only 18 minutes, greatly compressing the construction operation window. This shows that the unique raw material formula of the present invention can accurately regulate the setting time, effectively meeting the strict requirements of the rapid repair project of bridge expansion joints for timeliness while ensuring the construction operability, which is an innovative point that traditional materials and conventional ratios are difficult to achieve.

[0034] In terms of the development of early strength, in Examples 1-3, the 2-hour compressive strength reached 37.2-39.2 MPa, the 2-hour flexural strength reached 10.2-10.4 MPa, the 1-day compressive strength was 72.5-75.6 MPa, and the 1-day flexural strength was 11.3-11.8 MPa. In Comparative Example 1, since composite cement of Portland cement and rapid hardening sulfoaluminate cement was not used, the 2-hour compressive and flexural strengths were both 0, the 1-day compressive strength was only 38 MPa, and the flexural strength was 6.4 MPa; in Comparative Example 2, after removing the polycarboxylate superplasticizer powder, the 2-hour compressive strength decreased to 30.1 MPa, the flexural strength was 8.2 MPa, the 1-day compressive strength was 64.2 MPa, and the flexural strength was 10.1 MPa; in Comparative Example 3, after replacing the key components of the polycarboxylate superplasticizer powder of the present invention, each strength index was also lower than that of the example. The present invention realizes a leapfrog improvement in the ultra-early strength of the repair material through a specific cement composite system and the synergistic strengthening mechanism among various raw materials, can endow the expansion joint with a strong load-bearing capacity in a very short time, far exceeding the performance of traditional repair materials, effectively ensuring that the bridge quickly resumes the safe passage state after repair, greatly shortening the traffic interruption time, providing a new high-performance material solution for the rapid repair of bridges, and highlighting significant creative advantages.

[0035] In terms of working performance, for Examples 1 - 3, the mixing time required for the spread to reach 700 mm is only 6.5 - 7 minutes, and the spread can reach 600 - 685 mm after mixing for 7 minutes, showing good fluidity and dispersibility. In Comparative Example 2, due to the absence of the polycarboxylate water - reducing agent powder, the spread is only 430 mm after mixing for 8.5 minutes; in Comparative Example 3, after replacing the water - reducing agent, the spread is 560 mm after mixing for 7.5 minutes, both of which are inferior to the examples. The polycarboxylate water - reducing agent powder of the present invention is prepared by a unique preparation process, which effectively optimizes the rheological properties of the repair material, ensuring that during the rapid construction process, the repair material can quickly and evenly fill the damaged parts of the expansion joint, further improving the repair quality and efficiency. This is a key technical breakthrough that cannot be achieved by traditional repair materials, fully reflecting the creative contribution of the technical solution of the present invention in improving the comprehensive performance of the material, and providing a solid technical support and material guarantee for the rapid repair project of bridge expansion joint concrete.

[0036] The rapid repair material for bridge expansion joint notch concrete provided by the present invention can be applied in concrete construction, can quickly restore the bearing capacity of the expansion joint, effectively cope with complex working conditions such as vehicle impact, temperature change and erosion, has strong adhesion, good impact resistance and deformation resistance, makes up for the defects of traditional materials, greatly shortens the traffic interruption time, and is of great significance for ensuring the safe operation of bridges and improving durability. It is applicable to the rapid repair project of bridge expansion joint concrete.

[0037] Finally, it should be noted that: the above - mentioned embodiments are only used to illustrate the technical solutions of the present invention, not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A bridge expansion joint notch concrete quick repair material, characterized in that: The concrete is composed of the following raw materials in parts by weight: 850-900 parts of cement, 95-100 parts of silica fume, 790-800 parts of machine-made sand, 10-15 parts of early strength agent, 75-80 parts of steel fiber, 25-30 parts of expansion agent, 200-205 parts of water, 1.5-2 parts of sodium gluconate, and 15-20 parts of polycarboxylic acid water-reducing agent powder.

2. The bridge expansion joint notch concrete quick repair material according to claim 1 is characterized by: Calculated by weight, the polycarboxylic acid water-reducing agent powder is composed of 100-150 parts of methoxy polyethylene glycol ether acrylate, 18-32 parts of acrylic acid, 4-10 parts of thioglycolic acid, a pH adjusting agent, and 0.7%-5% of hydrogen peroxide based on the mass fraction of the total raw materials.

3. The bridge expansion joint notch concrete quick repair material according to claim 2 is characterized in that: The preparation method of the polycarboxylate water-reducing agent powder is as follows: In the reaction kettle, add purified water and methoxy polyethylene glycol ether acrylate in sequence and heat to 65-75°C; Add acrylic acid, thioglycolic acid and hydrogen peroxide dropwise within 4 hours, and then keep warm for reaction; The temperature is lowered to 40-50°C, and the pH value is neutralized to 7.0 with a pH adjusting agent to obtain a polycarboxylate water-reducing agent mother solution; The mother liquor is subjected to airflow spray drying to obtain a water reducing agent solid; The solid is ball-milled and sieved to obtain the polycarboxylate water-reducing agent powder.

4. The bridge expansion joint notch concrete quick repair material according to claim 1, characterized in that: The invention is composed of the following raw materials in parts by weight: 869 parts of cement, 97 parts of silica fume, 798 parts of machine-made sand, 14 parts of early strength agent, 78 parts of steel fiber, 29 parts of expansion agent, 203 parts of water, 1.9 parts of sodium gluconate and 19.3 parts of polycarboxylate water-reducing agent powder.

5. The quick concrete repair material for bridge expansion joint notch according to claim 1 is characterized by: The cement is composed of silicate cement and rapid hardening sulphoaluminate cement in a weight ratio of 255-260:300-610.

6. The quick concrete repair material for bridge expansion joint notch according to claim 1, characterized in that: The specific surface area of ​​the silica fume is 22000-22500 kg / m 2 .

7. The bridge expansion joint notch concrete quick repair material according to claim 1, characterized in that: The early strength agent is a crystal nucleus type early strength agent powder.

8. The bridge expansion joint notch concrete quick repair material according to claim 1, characterized in that: The expansion agent is a calcium aluminate expansion agent.

9. The method for preparing a quick concrete repair material for bridge expansion joint notches according to any one of claims 1 to 8, characterized in that: The following steps are involved: Weigh cement, silica fume, machine-made sand, early strength agent, sodium gluconate, steel fiber, expansion agent, polycarboxylate water-reducing agent powder, and water according to the proportion; Pour the above powder into a mixing pot for premixing, add water and stir, slowly add steel fiber and stir until the target fluidity is reached; Pour the stirred repair material into shape; The mold is removed after a period of time, and the bridge expansion joint groove concrete quick repair material is obtained after reaching a predetermined age.

10. Use of the quick concrete repair material for bridge expansion joint grooves as claimed in any one of claims 1 to 8 in concrete construction.

Images