Application of a multi-layer composite reinforcement material and its preparation method in preventing and controlling reflective cracks in widened roadbed

Abstract

The present invention belongs to the technical field of composite pavement structures, and specifically relates to the application of a multi-layer composite reinforcement material and its preparation method in the prevention and treatment of reflective cracks in widened roadbeds. The multi-layer composite reinforcement material comprises, from bottom to top, a stress absorption layer, an adhesive layer, and an asphalt concrete layer. The present invention selects specific raw materials so that each layer of material has specific stress absorption and dispersion capabilities, and through a specific preparation process, these layered materials are tightly combined together to form a composite reinforcement material with excellent crack resistance. It has excellent stress absorption, dispersion and bonding effects, can effectively alleviate stress concentration caused by roadbed deformation, reduce the occurrence of reflective cracks, and significantly improve the overall stability and crack resistance of the road structure, and is very suitable for the prevention and treatment of reflective cracks in widened roadbeds.

Description

Technical Field

[0001] The present invention belongs to the technical field of composite pavement structures, and in particular relates to an application of a multi-layer composite reinforcement material and a preparation method thereof in preventing and controlling reflective cracks in widened roadbeds. Background Art

[0002] With the ever-increasing demand for transportation, highway widening has become a critical task in current road construction. During highway widening, particularly during roadbed widening, reflective cracking is a common problem. Reflective cracking occurs when the road is widened over the existing roadbed. This is caused by the combined effects of uneven settlement of the new and old roadbeds, temperature and humidity fluctuations, and vehicle loads. These cracks gradually propagate upward, impacting the road's performance and service life.

[0003] Currently, common roadbed widening methods include single-sided splicing and double-sided widening. While single-sided splicing reduces construction space, in practice, the need for paving on the widened side makes it difficult to ensure uniform pavement thickness and overall smoothness. Double-sided widening, on the other hand, eliminates the need to adjust the pavement's arch slope, fully utilizing the existing pavement surface. Construction is relatively simple and cost-effective. However, regardless of the method, reflective cracking remains unavoidable.

[0004] To prevent and control reflective cracks, existing technical methods mainly include stress absorption, fiberglass grid reinforcement, and crack mitigation layer methods. The stress absorption method eliminates stress concentration and absorbs stress by placing an isolation layer, such as geotextile or oil felt, between the overlay layer and the original pavement. The fiberglass grid reinforcement method involves laying fiberglass grid in the overlay layer to enhance the overall tensile strength of the asphalt mixture and improve the stress distribution of the pavement structure, thereby resisting and delaying the occurrence of reflective cracks. The crack mitigation layer method uses materials such as large-particle permeable asphalt concrete to form a crack mitigation layer to mitigate the expansion of reflective cracks.

[0005] However, existing technologies still have limitations in preventing and controlling reflective cracks. For example, the choice of insulation layer material and installation process in the stress absorption method can affect its effectiveness; the fiberglass grid reinforcement method is less effective in preventing shear-type reflective cracks; and the crack mitigation layer method requires consideration of factors such as material properties, construction conditions, and long-term performance.

[0006] Therefore, developing a new type of multi-layer composite reinforcement material and its preparation method for preventing and treating reflective cracks in widened roadbed has important practical significance and application value. Summary of the Invention

[0007] The purpose of the present invention is to provide a multi-layer composite reinforcement material and a preparation method thereof, wherein the multi-layer composite reinforcement material has excellent stress absorption, dispersion and bonding effects, can effectively alleviate the stress concentration caused by roadbed deformation, reduce the occurrence of reflective cracks, and significantly improve the overall stability and crack resistance of the road structure.

[0008] In order to achieve the above object, the present invention provides the following technical solutions:

[0009] A multi-layer composite reinforcement material comprises, from bottom to top, a stress absorption layer, a bonding layer, and an asphalt concrete layer.

[0010] The raw materials for preparing the stress absorbing layer include gelling material, river sand, fiber, water reducing agent and water.

[0011] Preferably, the cementitious material includes cement, silica fume, and fly ash.

[0012] Preferably, the mass ratio of the cement, silica fume and fly ash is (2.5-3.5):1:(5-7); more preferably, it is 3:1:6.

[0013] Preferably, the cement is ordinary Portland cement with a P·O 42.5, an initial setting time of 220-230 min, a final setting time of 280-290 min, and a specific surface area of ​​350 m 2 / kg, sulfur trioxide content ≤2.2%.

[0014] In some preferred embodiments, the cement is purchased from Jidong Heidelberg (Jingyang) Cement Co., Ltd.

[0015] Preferably, the silica content in the silica fume is ≥92%, the loss on ignition is ≤2%, and the 7d activity index is ≥102%.

[0016] In some preferred embodiments, the silica fume is purchased from Gansu Sanyuan Silicon Materials Co., Ltd.

[0017] Preferably, the fly ash is first-grade fly ash, with a fineness (residue on a 45 mm square sieve) ≤ 9%, a water requirement ratio ≤ 93%, and a loss on ignition ≤ 2.7%.

[0018] In some preferred embodiments, the fly ash is purchased from Jinchang Zhongtianyuan Industry and Trade Co., Ltd.

[0019] Preferably, the particle size of the river sand is ≤0.2 mm, and all indicators meet the relevant requirements of GB / T 14684-2022 "Construction Sand", and the river sand is obtained by passing through a 0.5 mm sieve through commercially purchased river sand.

[0020] In some preferred embodiments, the river sand is purchased from the Manba River Sand Factory in Lintao County.

[0021] Preferably, the fibers include PVA fibers and modified carbon fibers.

[0022] Preferably, the volume ratio of the PVA fiber to the modified carbon fiber is (1-3):1; more preferably, it is 2:1.

[0023] Preferably, the PVA fiber has a diameter of 38-40 μm, a length of 12-13 μm, a tensile strength of 1550-1650 MPa, and an elongation at break of 6%-7%.

[0024] In some preferred embodiments, the PVA fiber is purchased from Kuraray of Japan.

[0025] The addition of PVA and carbon fibers to the stress-absorbing layer significantly improves the layer's strength and toughness, thereby enhancing the overall mechanical properties and durability of the multilayer composite reinforcement. This is likely due to a synergistic effect between PVA and carbon fibers. PVA fibers, with their excellent corrosion and weather resistance and good interfacial adhesion to the matrix material, enhance the material's overall strength, while carbon fibers effectively improve the material's tensile strength and stiffness. When used together, the two complement each other, significantly enhancing the overall strength of the stress-absorbing layer. Furthermore, the PVA fibers' flexibility and strain capacity help the material better absorb and disperse stress when subjected to external forces, preventing the formation and propagation of cracks. The carbon fibers' rigidity increases the material's resistance to deformation, enabling it to maintain structural integrity even under significant external forces. This combination significantly enhances the toughness and crack resistance of the stress-absorbing layer. However, carbon fibers are brittle, prone to cracking, and have poor thermal stability, potentially compromising the overall mechanical properties and durability of the stress-absorbing layer.

[0026] The method for preparing the modified carbon fiber comprises the following steps:

[0027] S1. Modification of nano-silica: After nano-silica is uniformly dispersed in an ethanol aqueous solution, a silane coupling agent is added, and the mixture is stirred at 60-70° C. for 4-6 hours, filtered, washed with deionized water 2-3 times, filtered under reduced pressure, and then vacuum dried to obtain modified nano-silica;

[0028] S2. Surface treatment and activation of carbon fiber: Place the carbon fiber in a beaker containing acetone and use an ultrasonic cleaner to clean it 2-3 times for 20-30 minutes each time, then dry it. Use oxygen plasma to treat the carbon fiber surface at a power of 45-55W for 3-5 minutes to obtain activated carbon fiber.

[0029] S3. Ultrasonic dispersion of modified nano-silica in toluene, immersion in activated carbon fiber, reaction at 80-100° C. for 3-5 hours, filtration, washing with ethanol 3-5 times, and vacuum drying at 100° C. to obtain modified carbon fiber.

[0030] Preferably, the nano-silicon dioxide includes a first nano-silicon dioxide, a second nano-silicon dioxide, and a third nano-silicon dioxide.

[0031] Preferably, the mass ratio of the first nano-silicon dioxide, the second nano-silicon dioxide, and the third nano-silicon dioxide is (0.5-2):(0.5-2):1; more preferably, it is 1:1:1.

[0032] Preferably, the average particle size of the first nano-silicon dioxide is 15 nm and the specific surface area is 250 m 2 / g.

[0033] Preferably, the average particle size of the second nano-silicon dioxide is 30 nm and the specific surface area is 200 m 2 / g.

[0034] Preferably, the average particle size of the third nano-silicon dioxide is 60 nm, and the specific surface area is 150 to 200 m 2 / g.

[0035] In some preferred embodiments, the nano-silicon dioxide is purchased from Beijing Dekedaojin Technology Co., Ltd.

[0036] Preferably, the volume concentration of ethanol in the ethanol aqueous solution is 60% to 70%.

[0037] Preferably, the mass ratio of the nano-silica to the ethanol aqueous solution is 1:(20-30).

[0038] Preferably, the silane coupling agent includes hexamethyldisilazane and γ-mercaptopropyltrimethoxysilane.

[0039] Preferably, the mass ratio of hexamethyldisilazane to γ-mercaptopropyltrimethoxysilane is (1-3):1; more preferably, it is 2:1.

[0040] Preferably, the added amount of the silane coupling agent is 10% to 20% of the mass of the nano-silicon dioxide.

[0041] Preferably, the carbon fiber has a diameter of 6-8 μm and a density of 1.70-1.80 g / cm 3 , elongation ≥1.5%, tensile strength ≥3GPa.

[0042] In some preferred embodiments, the carbon fiber is purchased from Jilin Jiyan High-Tech Fiber Co., Ltd.

[0043] Preferably, the mass ratio of the carbon fiber to acetone is 1:(20-40).

[0044] Preferably, the mass ratio of the modified nano-silica to toluene is 1:(80-100).

[0045] Preferably, the ultrasonic conditions are: power 100-200W, time 30-50min.

[0046] Preferably, the mass ratio of the modified nano-silica to the activated carbon fiber is 1:(2-4); more preferably, it is 1:3.

[0047] Modifying carbon fibers with nano-silica of different particle sizes can significantly improve defects such as high brittleness, easy cracking, and poor high-temperature resistance of carbon fibers, thereby improving the relevant properties of stress-absorbing layers and multi-layer composite reinforcements. This may be because, on the one hand, the surface of nano-silica is rich in active groups such as hydroxyl groups, which can chemically react or physically adsorb with the functional groups on the surface of carbon fibers, thereby enhancing the interfacial bonding between the carbon fibers and the matrix material, helping to reduce the generation and expansion of cracks and improving the overall strength of the material. On the other hand, the addition of nano-silica can fill the gaps between the carbon fibers to form a more compact structure. At the same time, nano-silica of different particle sizes can form a multi-level dispersed structure, which helps to disperse and absorb stress, thereby improving the toughness of the material, helping to reduce the brittle fracture of carbon fibers during stress, and extending the service life of the material. In addition, nano-silica has excellent thermal stability and can maintain structural stability at high temperatures. By introducing it into carbon fibers, the thermal stability of carbon fibers and their composite materials can be improved, reducing performance degradation in high-temperature environments, making them more suitable for road construction in extreme weather conditions.

[0048] Preferably, the water reducer is a polycarboxylate water reducer with a water reduction rate of ≥30%, a slurry fluidity of ≥210 mm, and a bulk density of 400-700 kg / m 3 .

[0049] In some preferred embodiments, the water reducer is purchased from Nanjing Xinyi Synthetic Technology Co., Ltd.

[0050] Preferably, the added amount of the water reducer is 1%-2% of the total mass of cement and fly ash.

[0051] Preferably, in the raw materials for preparing the stress absorbing layer, the water-binder ratio is 0.2-0.3, the sand-binder ratio is 0.3-0.4, and the fiber incorporation volume ratio is 1%-2.5%.

[0052] The method for preparing the stress absorbing layer comprises the following steps:

[0053] A1. Add the cementitious material and river sand into the mixer and stir at 100-150r / min for 3-5min;

[0054] A2. Mix water and water reducer, pour into a blender, stir at 100-150r / min for 3-5min, then stir at 200-300r / min for 3-5min, sprinkle in fiber and stir at 200-300r / min for 5-10min.

[0055] The raw materials for preparing the bonding layer include, by weight, 95-100 parts of a first matrix asphalt, 2-5 parts of rubber, 1-5 parts of a tackifying resin, and 0.5-1 part of a first emulsifier.

[0056] Preferably, the softening point of the first matrix asphalt is 45-50°C, the needle penetration at 25°C is 80-85 (0.1 mm), the elongation at 10°C is 65-70 cm, and the dynamic viscosity at 60°C is 165-180 Pa·s.

[0057] In some preferred embodiments, the first matrix asphalt is purchased from SK No. 90 asphalt in South Korea.

[0058] Preferably, the rubber comprises SBR.

[0059] Preferably, the SBR has a styrene content of 22%-25%, an elongation at break of ≥34%, and a volatility of 0.6%.

[0060] In some preferred embodiments, the SBR is purchased from Jilin Kunlun, 1502.

[0061] Preferably, the tackifying resin includes one or more of petroleum resin, rosin resin, and terpene resin; more preferably, it is petroleum resin.

[0062] Preferably, the petroleum resin is C9 hydrogenated petroleum resin with a softening point of 105-115° C. and an acid value of ≤1 mgKOH / g.

[0063] In some preferred embodiments, the petroleum resin is purchased from Puyang Hengtai Petrochemical Co., Ltd.

[0064] Preferably, the first matrix asphalt emulsifier is a diquaternary ammonium salt type medium-split cationic asphalt emulsifier with an active matter content of 48%-52% and a pH of 5-7.

[0065] In some preferred embodiments, the first matrix asphalt emulsifier is purchased from Shanghai Shijian Industrial Co., Ltd.

[0066] Selecting SK90 asphalt, with its high penetration and ductility, as the raw material for the bonding layer improves its flexibility and plasticity, facilitating a tight bond with the upper and lower pavement layers and adapting to pavement deformation and displacement. Modifying the asphalt with specific SBR and C9 hydrogenated petroleum resin significantly increases not only the viscosity of the bonding layer but also its temperature stability. This is likely due to the fact that, when SBR molecules are dispersed in the asphalt, they physically entangle and absorb oil from the asphalt, reducing the distance between asphaltenes and between asphaltene and the SBR. This increases the volume of the oil-absorbed SBR, increasing flow resistance and thus increasing the viscosity of the asphalt. Furthermore, due to the different moduli of the SBR rubber particles and the asphalt matrix, they can generate high stress concentrations at low temperatures, inducing numerous crazing and shear banding, consuming significant energy, and improving the impact strength and plasticity of the bonding layer. The larger SBR rubber particles also prevent the growth and breakage of individual crazing, preventing them from rapidly developing into destructive cracks, thereby improving the asphalt's low-temperature flexibility. Furthermore, the C9 hydrogenated petroleum resin exhibits excellent miscibility and thermal stability. When added to asphalt, it can cross-link with the asphalt to form an interconnected spatial network structure, thereby increasing the viscosity of the asphalt. In the bonding layer, the first matrix asphalt serves as the foundation, forming a tight structure with SBR through physical adsorption, diffusion, and possible chemical bonding. At the same time, it uses polar interactions and molecular chain entanglement with C9 hydrogenated petroleum resin to enhance adhesion and cohesion. The diquaternary ammonium salt-type medium-crack cationic asphalt emulsifier ensures the uniform dispersion and stability of the asphalt through emulsification dispersion and interfacial film formation, while promoting interfacial bonding with other raw materials. The combination of SBR and C9 hydrogenated petroleum resin not only enhances adhesion, but also improves the elastic modulus and processing performance. The synergistic effect of C9 hydrogenated petroleum resin and emulsifier further stabilizes the emulsification system, optimizes the microstructure, and enhances interfacial bonding. These synergistic effects jointly improve the adhesion, durability, crack resistance, and peeling resistance of the bonding layer, thereby enhancing the overall performance and service life of the multi-layer composite reinforced material.

[0067] The preparation method of the bonding layer includes the following steps: heating the first matrix asphalt to 155-165°C, adding rubber, tackifying resin, and a first emulsifier, stirring for 1-2 hours, heating to 170-180°C, shearing with a colloid mill at a speed of 3000-4000 r / min for 1-2 hours, continuing to heat to 180-190°C, shearing with a colloid mill at a speed of 3000-4000 r / min for 1-2 hours, stopping shearing, stirring and maturing for 30-60 minutes, and cooling to obtain the bonding layer.

[0068] The raw materials for preparing the asphalt concrete layer include modified asphalt, curing agent and mineral material.

[0069] The raw materials for preparing the modified asphalt include, by weight, 95-105 parts of second matrix asphalt, 3-8 parts of thermoplastic elastomer, 8-15 parts of epoxy resin, 0.5-1 part of second matrix asphalt emulsifier, and 1-2.5 parts of epoxy resin emulsifier.

[0070] Preferably, the softening point of the second matrix asphalt is 45-50°C, the needle penetration at 25°C is 66-70 (0.1 mm), the elongation at 10°C is 18-22 cm, and the dynamic viscosity at 60°C is 210-220 Pa·s.

[0071] In some preferred embodiments, the second matrix asphalt is purchased from Maoming Branch of Sinopec Co., Ltd., No. 70 Road Petroleum Asphalt (1-4) (Grade A).

[0072] Preferably, the thermoplastic elastomer is SBS, has a melt flow rate of 2-5 g / 10 min at 190° C., a volatility of ≤0.8%, and a total styrene content of 38%-42%.

[0073] In some preferred embodiments, the SBS is purchased from Dushanzi Petrochemical, T171 E.

[0074] Preferably, the epoxy resin is bisphenol A epoxy resin, with an epoxy equivalent of 230-290 mol / 100g and a softening point of 21-27°C.

[0075] In some preferred embodiments, the epoxy resin is purchased from Laizhou Baichen Insulation Material Co., Ltd., resin E-42.

[0076] The use of specific SBS and bisphenol A epoxy resin to modify No. 70 asphalt can significantly improve the crack resistance, overall stability and construction performance of the asphalt concrete layer, providing a more reliable material guarantee for the prevention and control of reflective cracks in widened roadbeds. This may be because the addition of SBS significantly enhances the elastic recovery and low-temperature crack resistance of the asphalt. Through its soft segment, it absorbs the light oil in the asphalt and fully swells to form a spatial network system, effectively reducing cracks caused by temperature changes. At the same time, bisphenol A epoxy resin undergoes a cross-linking reaction with the functional groups on the asphalt molecules to form a three-dimensional interpenetrating network structure, which greatly improves the high-temperature stability and adhesion of the asphalt and fundamentally changes the thermoplasticity of ordinary asphalt. The synergistic effect of the two not only complements each other, improving the elasticity, strength and stability of the modified asphalt, but also optimizes the cross-linking reaction process, making the reaction more complete and uniform.

[0077] Preferably, the second matrix asphalt emulsifier is a cationic amide slow-cracking and fast-setting emulsifier with an active matter content of 89%-91% and a pH value of 6-7.

[0078] In some preferred embodiments, the second matrix asphalt emulsifier is purchased from Shandong Boxing County Haolong Chemical Co., Ltd.

[0079] Preferably, the epoxy resin emulsifier is a non-ionic water-dispersible emulsion with a solid content of 38%-42%, a viscosity of 900-1200 mP·s at 25° C., and a specific gravity of 1.01-1.08.

[0080] In some preferred embodiments, the epoxy resin emulsifier is purchased from Dongguan Guangtong Chemical Products Co., Ltd.

[0081] The preparation method of the modified asphalt comprises the following steps:

[0082] B1. Preparation of epoxy resin emulsion: epoxy resin, epoxy resin emulsifier and water are mixed and sheared at a speed of 3000-4000 r / min for 30-50 min to obtain epoxy resin emulsion;

[0083] B2. Preparation of modified second matrix asphalt: dissolving a second matrix asphalt emulsifier in 60° C. water to obtain a second matrix asphalt emulsifier solution; raising the temperature of the second matrix asphalt to 175-180° C., adding the second matrix asphalt emulsifier solution, and shearing the mixture using a colloid mill at a speed of 3000-4000 r / min for 20-40 minutes. Then, adding a thermoplastic elastomer, and continuing to shear the mixture using a colloid mill at a speed of 3000-4000 r / min for 40-60 minutes. The mixture is cooled to obtain the modified second matrix asphalt;

[0084] B3. Mix the epoxy resin emulsion and the modified second matrix asphalt, and shear at a speed of 300-500 r / min for 5-10 minutes to obtain.

[0085] Preferably, the amount of water added in step B1 is consistent with the mass of the epoxy resin.

[0086] Preferably, the amount of water added in step B2 is 90-110 times the mass of the second matrix asphalt emulsifier.

[0087] Preferably, the solid content of the curing agent is 43%-47%, the viscosity at 25° C. is 7700-9600 mP·s, and the amine hydrogen equivalent is 220-280.

[0088] In some preferred embodiments, the curing agent is purchased from Dongguan Guangtong Chemical Products Co., Ltd.

[0089] The mineral materials include coarse aggregate, fine aggregate and filler. The specific proportions and properties are referred to the article "Research on Flexural Properties and Triaxial Static and Dynamic Characteristics of SBS Modified Asphalt Concrete for Anti-seepage Layer in Cold Regions" published by Ning Fengwei et al.

[0090] Preferably, the mass ratio of the modified asphalt to the curing agent is (2-3):1; further preferably, it is 5:2.

[0091] Preferably, the mass of the modified asphalt is 8%-15% of the mass of the mineral material, and the gradation index is 0.43.

[0092] The preparation method of the asphalt concrete layer comprises the following steps: mixing modified asphalt and a curing agent, shearing for 5-10 minutes at 150-160° C. and 800-1200 r / min, adding mineral material, and stirring for 20-40 minutes to obtain the asphalt concrete layer.

[0093] The second aspect of the present invention provides a method for preparing the multi-layer composite reinforced material, comprising the steps of: simultaneously spreading a stress absorption layer, an adhesive layer, and an asphalt concrete layer, compacting the layer, and curing the layer at room temperature for 28 days.

[0094] Preferably, the stress absorption layer has a thickness of 6-10 mm.

[0095] Preferably, the amount of the adhesive layer sprayed is 1-1.2 kg / m 2

[0096] Preferably, the thickness of the asphalt concrete layer is 4-8 mm.

[0097] In some preferred solutions, the stress absorbing layer and the asphalt concrete layer are heated to 180-190°C before spreading, and the bonding layer temperature is 160-170°C.

[0098] The third aspect of the present invention provides the application of the multi-layer composite reinforcement material in preventing and controlling reflective cracks in a widened roadbed, and the specific application method is as follows:

[0099] C1. Excavate the cracks, clean the excavated area, fill the cracks with filling material, and use a 10-ton roller to compact the filled road surface;

[0100] C2. Pour the caulking material into the cracks of the pavement, control the temperature of the caulking material between 160-180℃, and after the cracks of the pavement are fully filled, simultaneously spread the stress absorption layer, bonding layer, and asphalt concrete layer, compact them and maintain for 28 days.

[0101] Preferably, the filling material is not specifically limited and can be gravel, concrete or other materials with a particle size of 10-30 mm.

[0102] The raw materials and preparation method of the caulking material are consistent with those of the bonding layer.

[0103] Compared with the prior art, the advantages and beneficial effects of the present invention are:

[0104] 1. The present invention provides a multi-layer composite reinforcement material comprising, from bottom to top, a stress-absorbing layer, an adhesive layer, and an asphalt concrete layer. By selecting specific raw materials, each layer possesses specific stress absorption and dispersion capabilities. Through a specific preparation process, these layered materials are tightly bonded together to form a composite reinforcement material with excellent crack resistance. This material exhibits excellent stress absorption, dispersion, and bonding properties, effectively alleviating stress concentration caused by roadbed deformation, reducing the occurrence of reflective cracks, and significantly improving the overall stability and crack resistance of road structures. It is highly suitable for preventing and controlling reflective cracks in widened roadbeds.

[0105] 2. By adding PVA fibers and carbon fibers to the stress absorbing layer, the present invention can significantly improve the strength and toughness of the stress absorbing layer, thereby improving the overall mechanical properties and durability of the multilayer composite reinforced material.

[0106] 3. The present invention modifies carbon fibers using nano-silica of different particle sizes, which can significantly improve defects such as high brittleness, susceptibility to cracking, and poor high-temperature resistance of carbon fibers, thereby improving the relevant properties of stress-absorbing layers and multi-layer composite reinforcement materials.

[0107] 4. The present invention uses SK90 asphalt with large needle penetration and high ductility as the raw material of the bonding layer, which can improve the flexibility and plasticity of the bonding layer, facilitate its close bonding with the upper and lower road surfaces, and adapt to the deformation and displacement of the road surface.

[0108] 5. The present invention uses specific SBS and bisphenol A epoxy resin to modify No. 70 asphalt, which can significantly improve the crack resistance, overall stability and construction performance of the asphalt concrete layer, providing a more reliable material guarantee for the prevention and control of reflective cracks in widened roadbeds. DETAILED DESCRIPTION

[0109] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0110] The raw materials used in the present invention are all commercially available, specifically:

[0111] The cement is ordinary Portland cement with a P·O 42.5, an initial setting time of 220-230 min, a final setting time of 280-290 min, and a specific surface area of ​​≥350 m 2 / kg, sulfur trioxide content ≤2.2%, purchased from Jidong Heidelberg (Jingyang) Cement Co., Ltd.

[0112] The silica fume has a silicon dioxide content of ≥92%, a loss on ignition of ≤2%, and a 7d activity index of ≥102%, and was purchased from Gansu Sanyuan Silicon Materials Co., Ltd.

[0113] The fly ash was first-grade fly ash with a fineness (residue on a 45 mm square sieve) of ≤9%, a water requirement ratio of ≤93%, and a loss on ignition of ≤2.7%, purchased from Jinchang Zhongtianyuan Industry and Trade Co., Ltd.

[0114] The particle size of river sand is ≤0.2mm, and all indicators meet the relevant requirements of GB / T 14684-2022 "Construction Sand". It is city-purchased river sand that has passed through a 0.5mm sieve and was purchased from the Manba River Sand Factory in Lintao County.

[0115] The PVA fiber has a diameter of 38-40 μm, a length of 12-13 μm, a tensile strength of 1550-1650 MPa, and an elongation at break of 6%-7%, and was purchased from Kuraray, Japan.

[0116] The average particle size of the first nano-silica is 15 nm and the specific surface area is 250 m 2 / g; the average particle size of the second nano-silica is 30nm and the specific surface area is 200m 2 / g; the average particle size of the third nano-silicon dioxide is 60nm, and the specific surface area is 150-200m 2 / g; all purchased from Beijing Dekedao Gold Technology Co., Ltd.

[0117] The diameter of carbon fiber is 6-8μm and the density is 1.70-1.80g / cm 3 , elongation ≥ 1.5%, tensile strength ≥ 3 GPa, purchased from Jilin Jiyan High-tech Fiber Co., Ltd.

[0118] The water reducer is polycarboxylate water reducer, with a water reduction rate of ≥30%, a slurry fluidity of ≥210mm, and a bulk density of 400-700kg / m 3 , purchased from Nanjing Xinyi Synthetic Technology Co., Ltd.

[0119] The first matrix asphalt has a softening point of 45-50°C, a needle penetration of 80-85 (0.1 mm) at 25°C, an elongation of 65-70 cm at 10°C, and a dynamic viscosity of 165-180 Pa·s at 60°C. It is purchased from SK, South Korea, and is No. 90 asphalt.

[0120] The styrene content of SBR is 22%-25%, the elongation at break is ≥34%, and the volatility is 0.6%. It is purchased from Jilin Kunlun, 1502.

[0121] C9 hydrogenated petroleum resin, softening point of 105-115 °C, acid value ≤1 mgKOH / g, was purchased from Puyang Hengtai Petrochemical Co., Ltd.

[0122] The first matrix asphalt emulsifier is a diquaternary ammonium salt type medium-crack cationic asphalt emulsifier with an active matter content of 48%-52% and a pH of 5-7, purchased from Shanghai Shijian Industrial Co., Ltd.

[0123] The second matrix asphalt has a softening point of 45-50°C, a needle penetration of 66-70 (0.1 mm) at 25°C, an elongation of 18-22 cm at 10°C, and a dynamic viscosity of 210-220 Pa·s at 60°C. It was purchased from Maoming Branch of Sinopec, No. 70 Road Petroleum Asphalt (1-4) (Grade A).

[0124] SBS has a melt flow rate of 2-5 g / 10 min at 190°C, a volatility of ≤0.8%, and a total styrene content of 38%-42%. It was purchased from Dushanzi Petrochemical, T171 E.

[0125] Bisphenol A epoxy resin, with an epoxy equivalent of 230-290 mol / 100 g and a softening point of 21-27°C, was purchased from Laizhou Baichen Insulation Material Co., Ltd., resin E-42.

[0126] The second matrix asphalt emulsifier is a cationic amide slow-cracking and fast-setting emulsifier with an active matter content of 89%-91% and a pH value of 6-7, purchased from Shandong Boxing County Haolong Chemical Co., Ltd.

[0127] The epoxy resin emulsifier is a non-ionic water-dispersible emulsion with a solid content of 38%-42%, a viscosity of 900-1200 mP·s at 25° C., and a specific gravity of 1.01-1.08, purchased from Dongguan Guangtong Chemical Products Co., Ltd.

[0128] The curing agent has a solid content of 43%-47%, a viscosity of 7700-9600 mP·s at 25° C., and an amine hydrogen equivalent of 220-280, and is purchased from Dongguan Guangtong Chemical Products Co., Ltd.

[0129] Example 1

[0130] This embodiment provides a multi-layer composite reinforcement material, which comprises, from bottom to top, a stress absorption layer, an adhesive layer, and an asphalt concrete layer.

[0131] The raw materials for preparing the stress absorbing layer are gelling material, river sand, fiber, water reducing agent and water.

[0132] The cementitious materials are cement, silica fume and fly ash, with a mass ratio of 3:1:6.

[0133] The fibers are PVA fibers and modified carbon fibers, with a volume ratio of 2:1.

[0134] The preparation method of the modified carbon fiber comprises the following steps:

[0135] S1. Modification of nano-silica: After nano-silica is dispersed evenly in an ethanol aqueous solution, a silane coupling agent is added, and the mixture is stirred at 65°C for 5 hours, filtered, washed with deionized water three times, filtered under reduced pressure, and vacuum dried to obtain modified nano-silica;

[0136] S2. Surface treatment and activation of carbon fiber: The carbon fiber was placed in a beaker containing acetone and cleaned three times with an ultrasonic cleaner for 25 minutes each time, followed by drying. The carbon fiber surface was treated with oxygen plasma at a power of 50 W for 4 minutes to obtain activated carbon fiber.

[0137] S3. Ultrasonic dispersion of modified nano-silica in toluene was performed, and the activated carbon fiber was immersed therein. After reacting at 90°C for 4 hours, the modified carbon fiber was filtered, rinsed with ethanol 4 times, and vacuum dried at 100°C to obtain the modified carbon fiber.

[0138] The nano-silicon dioxide comprises first nano-silicon dioxide, second nano-silicon dioxide and third nano-silicon dioxide, with a mass ratio of 1:1:1.

[0139] The volume concentration of ethanol in the ethanol aqueous solution is 65%.

[0140] The mass ratio of the nano-silica to the ethanol aqueous solution is 1:20.

[0141] The silane coupling agent is hexamethyldisilazane and γ-mercaptopropyltrimethoxysilane, with a mass ratio of 2:1.

[0142] The added amount of the silane coupling agent is 15% of the mass of the nano-silicon dioxide.

[0143] The mass ratio of the carbon fiber to acetone is 1:30.

[0144] The mass ratio of the modified nano-silica to toluene is 1:90.

[0145] The ultrasonic conditions are: power 150W, time 40min.

[0146] The mass ratio of the modified nano-silica to the activated carbon fiber is 1:3.

[0147] The added amount of the water reducer is 1.5% of the total mass of cement and fly ash.

[0148] The raw materials for preparing the stress absorbing layer have a water-to-binder ratio of 0.25, a sand-to-binder ratio of 0.35, and a fiber incorporation volume ratio of 2%.

[0149] The preparation method of the stress absorption layer comprises the following steps:

[0150] A1. Add the cementitious material and river sand into the mixer and stir at 120 r / min for 4 minutes;

[0151] A2. Mix water and water reducer, pour into a blender, stir at 120r / min for 4 minutes, then at 250r / min for 4 minutes, sprinkle in fiber and stir at 250r / min for 8 minutes.

[0152] The raw materials for preparing the bonding layer include, by weight, 100 parts of a first matrix asphalt, 4 parts of rubber, 4 parts of a tackifying resin, and 0.5 parts of a first emulsifier.

[0153] The rubber is SBR.

[0154] The tackifying resin is petroleum resin.

[0155] The preparation method of the bonding layer includes the following steps: heating the first matrix asphalt to 160°C, adding rubber, tackifying resin, and the first emulsifier, stirring for 1.5 hours, heating to 175°C, shearing with a colloid mill at a speed of 3500 r / min for 1.5 hours, continuing to heat to 185°C, shearing with a colloid mill at a speed of 3500 r / min for 1.5 hours, stopping shearing, stirring and maturing for 45 minutes, and cooling to obtain the product.

[0156] The raw materials for preparing the asphalt concrete layer are modified asphalt, curing agent and mineral material.

[0157] The raw materials for preparing the modified asphalt are, by weight, 100 parts of the second matrix asphalt, 5 parts of thermoplastic elastomer, 12 parts of epoxy resin, 0.5 parts of the second matrix asphalt emulsifier, and 2 parts of epoxy resin emulsifier.

[0158] The thermoplastic elastomer is SBS.

[0159] The epoxy resin is bisphenol A epoxy resin.

[0160] The preparation method of the modified asphalt comprises the following steps:

[0161] B1. Preparation of epoxy resin emulsion: epoxy resin, epoxy resin emulsifier and water were mixed and sheared at a speed of 3500 r / min for 40 min to obtain epoxy resin emulsion;

[0162] B2. Preparation of modified second matrix asphalt: dissolving a second matrix asphalt emulsifier in 60° C. water to obtain a second matrix asphalt emulsifier solution; raising the temperature of the second matrix asphalt to 175° C., adding the second matrix asphalt emulsifier solution, and shearing the mixture on a colloid mill at a speed of 3500 r / min for 30 minutes. Then, adding a thermoplastic elastomer, and continuing to shear the mixture on a colloid mill at a speed of 3500 r / min for 50 minutes. The mixture was cooled to obtain the modified second matrix asphalt;

[0163] B3. Mix the epoxy resin emulsion and the modified second matrix asphalt, and shear them at a speed of 400r / min for 8 minutes to obtain the product.

[0164] The amount of water added in step B1 is consistent with the mass of the epoxy resin.

[0165] The amount of water added in step B2 is 100 times the mass of the second matrix asphalt emulsifier.

[0166] The mineral materials include coarse aggregate, fine aggregate and filler. The specific proportions and properties are referred to the article "Research on Flexural Properties and Triaxial Static and Dynamic Characteristics of SBS Modified Asphalt Concrete for Anti-seepage Layer in Cold Regions" published by Ning Fengwei et al.

[0167] The mass ratio of the modified asphalt to the curing agent is 5:2.

[0168] The mass of the modified asphalt is 12% of the mass of the mineral material, and the gradation index is 0.43.

[0169] The preparation method of the asphalt concrete layer comprises the following steps: mixing the modified asphalt and the curing agent, shearing for 8 minutes at 155° C. and 1000 r / min, adding mineral material, and stirring for 30 minutes to obtain the asphalt concrete layer.

[0170] The preparation method of the multi-layer composite reinforced material comprises the following steps: simultaneously spreading a stress absorption layer, an adhesive layer, and an asphalt concrete layer, compacting the layer, and curing the layer at room temperature for 28 days.

[0171] The thickness of the stress absorbing layer is 8 mm.

[0172] The amount of the adhesive layer sprayed is 1.2 kg / m 2 .

[0173] The thickness of the asphalt concrete layer is 6 mm.

[0174] In some preferred embodiments, the stress absorbing layer and the asphalt concrete layer are heated to 185°C before spreading, and the bonding layer temperature is 165°C.

[0175] Example 2

[0176] The difference between this embodiment and embodiment 1 is that the thickness of the stress absorption layer is 10 mm.

[0177] The amount of the adhesive layer sprayed is 1.1 kg / m 2 .

[0178] The thickness of the asphalt concrete layer is 4 mm.

[0179] Comparative Example 1

[0180] The difference between this comparative example and Example 1 is that the fiber is PVA fiber.

[0181] Comparative Example 2

[0182] The difference between this comparative example and Example 1 is that the fibers are PVA fibers and carbon fibers, and the volume ratio is 2:1.

[0183] Comparative Example 3

[0184] The difference between this comparative example and Example 1 is that the nano-silicon dioxide is the first nano-silicon dioxide.

[0185] Comparative Example 4

[0186] The difference between this comparative example and Example 1 is that the raw materials for preparing the bonding layer include, by weight, 100 parts of a first matrix asphalt, 4 parts of a tackifying resin, and 0.5 parts of a first emulsifier.

[0187] Comparative Example 5

[0188] The difference between this comparative example and Example 1 is that the first matrix asphalt and the second matrix asphalt are the same, both purchased from Maoming Branch of Sinopec Co., Ltd., No. 70 Road Petroleum Asphalt (1-4) (Grade A).

[0189] Comparative Example 6

[0190] The difference between this comparative example and Example 1 is that the raw materials for preparing the modified asphalt are, by weight, 100 parts of the second matrix asphalt, 5 parts of the thermoplastic elastomer, 0.5 parts of the second matrix asphalt emulsifier, and 2 parts of the epoxy resin emulsifier.

[0191] Comparative Example 7

[0192] The difference between this comparative example and Example 1 is that the raw materials for preparing the modified asphalt are, by weight, 100 parts of the second matrix asphalt, 5 parts of EVA emulsion, 12 parts of epoxy resin, 0.5 parts of the second matrix asphalt emulsifier, and 2 parts of epoxy resin emulsifier.

[0193] The EVA emulsion has a solid content of 53%-57% and a viscosity of 3500-4500 mPa at 25° C. and is purchased from Dalian Chemical Industry Co., Ltd. in Taiwan, China, and is labeled DA-102H.

[0194] Performance Testing

[0195] Following the method described in patent CN 1083603277A, the Marshall method was used to test the high-temperature rutting resistance (65°C dynamic stability) and low-temperature cracking resistance (flexural failure strain, flexural tensile strength, and strain energy) of multilayer composite reinforcements. Higher dynamic stability indicates a stronger resistance to high-temperature deformation; higher failure strain and strain energy indicate better low-temperature cracking resistance. The results are shown in Table 1.

[0196] Table 1 Measurement results

[0197]

[0198] According to statistics, the multilayer composite reinforced materials prepared by Examples 1 to 2 of the present invention have strong high-temperature rutting resistance and low-temperature cracking resistance. Comparative Example 1 only has PVA fiber, Comparative Example 2 does not modify the carbon fiber, Comparative Example 3 only has the first nanosilica, Comparative Example 4 does not add SBR rubber to the bonding layer, Comparative Example 5 has the same first matrix asphalt as the second matrix asphalt, Comparative Example 6 does not add epoxy resin to the modified asphalt, and Comparative Example 7 uses EVA emulsion instead of thermoplastic elastomer SBS. The prepared multilayer composite reinforced materials have poor high-temperature rutting resistance and low-temperature cracking resistance. Therefore, the multilayer composite reinforced materials prepared using the raw materials and methods described in this application have excellent stress absorption, dispersion and bonding effects, can effectively alleviate the stress concentration caused by roadbed deformation, reduce the generation of reflective cracks, and significantly improve the overall stability and crack resistance of the road structure.

[0199] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A multi-layer composite reinforced material, characterized in that: From bottom to top, they are stress absorption layer, bonding layer, and asphalt concrete layer; The raw materials for preparing the stress absorbing layer include a cementitious material, river sand, fibers, a water reducing agent, and water; the fibers include PVA fibers and modified carbon fibers; the PVA fibers have a diameter of 38-40 μm, a length of 12-13 μm, a tensile strength of 1550-1650 MPa, and an elongation at break of 6%-7%; The preparation method of modified carbon fiber includes: S1. Modification of nano-silica: After nano-silica is uniformly dispersed in an ethanol aqueous solution, a silane coupling agent is added, and the mixture is stirred at 60-70° C. for 4-6 hours, filtered, washed with deionized water 2-3 times, filtered under reduced pressure, and then vacuum dried to obtain modified nano-silica; S2. Surface treatment and activation of carbon fiber: Place the carbon fiber in a beaker containing acetone and use an ultrasonic cleaner to clean it 2-3 times for 20-30 minutes each time, then dry it. Use oxygen plasma to treat the carbon fiber surface at a power of 45-55W for 3-5 minutes to obtain activated carbon fiber. S3, ultrasonically dispersing the modified nano-silica in toluene, immersing the activated carbon fiber, reacting at 80-100°C for 3-5 hours, filtering, rinsing with ethanol 3-5 times, and vacuum drying at 100°C to obtain the modified carbon fiber; The nano-silicon dioxide comprises a first nano-silicon dioxide, a second nano-silicon dioxide and a third nano-silicon dioxide, with a mass ratio of (0.5-2): (0.5-2): 1; The average particle size of the first nano-silica is 15 nm and the specific surface area is 250 m 2 / g; The average particle size of the second nano-silica is 30nm and the specific surface area is 200m 2 / g; The average particle size of the third nano-silicon dioxide is 60nm, and the specific surface area is 150-200m 2 / g; The raw materials for preparing the bonding layer include, by weight, 95-100 parts of the first matrix asphalt, 2-5 parts of rubber, 1-5 parts of tackifying resin, and 0.5-1 part of the first emulsifier; Raw materials for preparing asphalt concrete layer, including modified asphalt, curing agent, and mineral aggregate; The raw materials for preparing the modified asphalt include, by weight, 95-105 parts of second matrix asphalt, 3-8 parts of thermoplastic elastomer, 8-15 parts of epoxy resin, 0.5-1 part of second matrix asphalt emulsifier, and 1-2.5 parts of epoxy resin emulsifier.

2. The multilayer composite reinforced material according to claim 1, characterized in that: The carbon fiber has a diameter of 6 to 8 μm and a density of 1.70 to 1.80 g / cm 3 , elongation ≥1.5%, tensile strength ≥3GPa.

3. The multilayer composite reinforced material according to claim 2, characterized in that: The softening point of the first matrix asphalt is 45-50°C, the needle penetration at 25°C is 80-85 (0.1 mm), the elongation at 10°C is 65-70 cm, and the dynamic viscosity at 60°C is 165-180 Pa·s.

4. The multilayer composite reinforced material according to claim 3, characterized in that: The rubber comprises SBR; the styrene content of the SBR is 22%-25%, the elongation at break is ≥34%, and the volatility is 0.6%.

5. A method for preparing a multilayer composite reinforced material according to any one of claims 1 to 4, characterized in that: The steps are: simultaneously spreading the stress absorption layer, bonding layer and asphalt concrete layer, compacting and curing at room temperature for 28 days.

6. Use of the multilayer composite reinforcement material according to any one of claims 1 to 4 in preventing and controlling reflective cracks in widened roadbeds.

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