Polyurethane sealant for joint of cement concrete pavement

Abstract

The invention belongs to the technical field of polyurethane waterproof coatings, and particularly relates to a polyurethane sealant for a joint of a cement concrete pavement. The preparation method comprises the following steps: compounding polyether glycol, polyether triol, a plasticizer I and other components to prepare a polyurethane prepolymer as a component A, compounding micromolecular polyol, macromolecular polyether polyol, calcium hydroxide, a plasticizer II, a catalyst, a filler and other components to prepare a cross-linking agent mixture as a component B, and finally compounding the component A and the component B under certain conditions. The polyurethane sealant for the joint of the cement concrete pavement is prepared and has the characteristics of resistance to high and low temperatures of extreme weather, aging resistance, high adhesion, high curing speed and the like when being used for construction at the joint of the cement concrete pavement, so that various defects of an existing joint pouring material are overcome.

Description

Technical Field

[0001] This invention belongs to the field of polyurethane waterproof coating technology, specifically relating to a polyurethane sealant for joints in cement concrete pavements. Background Technology

[0002] Waterproofing and resistance to embedding are the core requirements for sealants used in highways. Current technology treats cement concrete pavement joints by filling the upper 2-3cm space of the joint with elastic sealant (with a foam strip underneath and a 1-1.5cm thick sealant layer on top) to seal the joint and prevent moisture penetration and gravel embedding.

[0003] The current state of joint treatment in cement concrete pavements (especially highways) is such that numerous broken and hollow slabs are prone to occur. The primary reason is inadequate sealing of the joints, allowing surface water to seep into the foundation, eroding the subgrade and causing voids in the slab surface. Under repeated heavy loads, this leads to slab damage and poses a significant threat to traffic safety. The main reasons for this situation are as follows: 1. The quality of commonly available crack sealing materials varies greatly, and the product quality does not meet the design requirements. Common silane-modified polyether (commonly known as MS glue) materials and asphalt-based crack sealing materials are far from meeting the needs of road crack sealing.

[0004] 2. The "Technical Specifications for Construction of Cement Concrete Pavement on Highways" (JTG / T F30-2014) states that a single joint sealant cannot simultaneously meet the contradictory technical requirements of not flowing, softening, or embedding under extreme high temperatures, and not cracking or breaking under extreme low temperatures. In other words, for joint treatment materials to have good embedding resistance, high material modulus, high strength, and high elastic recovery are required; however, for the same material, both strong adhesion and fatigue resistance, as well as good flexibility and low modulus, are two contradictory indicators. From a material performance perspective, existing materials all exhibit this deficiency.

[0005] 3. The material must maintain good adhesion and fatigue resistance under long-term and frequent horizontal forces, as well as under vertical forces. The shape factor of the injection material can also cause the adhesion and fatigue resistance in these two directions to become contradictory. This requires the material modulus to be as low as possible, but existing materials often cannot meet the corresponding requirements.

[0006] 4. Highway joint construction is carried out in an outdoor environment. In joints 5-8mm wide, maintaining the material's adhesion to the joint walls requires excellent workability: a moderate viscosity to ensure good penetration into the bonding surface while also ensuring rapid solidification, reaching the required performance within the shortest possible time to guarantee construction quality. Conversely, a slightly thicker material is needed to ensure rapid curing after pouring. In short, the material requirements are low viscosity and rapid curing.

[0007] 5. Years of exposure to sun and rain are the most stringent test of the weather resistance of cement concrete pavement sealing materials. In the existing technology, silane-modified polyether (commonly known as MS glue) is often used as a potting compound for the treatment of cement concrete pavement joints. However, it is a single-component product with extremely poor weather resistance. It will show obvious aging in about half a month. Moreover, due to the principle of moisture curing, the internal curing speed is extremely slow after use. It will become severely aged and fail after 6 months.

[0008] 6. In many places, asphalt-based crack sealant is used. It is poured into the cracks after being melted by heat. This material has poor high and low temperature performance. In summer, when the road surface is hot, the material is very soft, has fluidity, poor strength, and easily sticks to the wheels. In winter, the material hardens and cracks. This phenomenon is particularly obvious in Northwest my country, which affects its performance.

[0009] The solution to the above problems lies in the quality standards for polyurethane-based room-temperature construction joint sealants in the "Technical Specifications for Construction of Cement Concrete Pavement on Highways" (JTG / T F30-2014). Specifically, improvements need to be made to properties such as tensile modulus, adhesion at a given elongation, elongation at -10℃, water resistance, and crack resistance at negative temperatures. Furthermore, the elastic recovery rate and high-temperature resistance should meet the requirements for high-modulus products. Shorter surface drying time and detack curing time are preferable, and longer resistance to accelerated aging caused by light, oxygen, and heat is also desirable.

[0010] Through years of practical experience, the inventors have discovered that polyurethane sealant is an ideal choice for joints in cement concrete pavements, considering both its construction and performance characteristics. It offers the following advantages: 1) Improved durability under various harsh outdoor conditions (e.g., continuous stress damage from high temperatures, extreme cold, sun exposure, and rain). 2) In today's high-traffic environment, construction materials are often damaged before they meet performance requirements (due to slow response and inability to meet modern joint maintenance needs), whereas polyurethane sealant offers rapid application.

[0011] In summary, the core requirements for joint treatment in cement concrete pavements are waterproofing and resistance to embedment. However, achieving these two requirements involves conflicting material performance requirements. This application proposes a novel polyurethane sealant material to resolve these contradictions, thereby improving product quality and meeting market demands. Summary of the Invention

[0012] To address the shortcomings of existing technologies, this invention prepares a polyurethane prepolymer as component A by compounding polyether diol, polyether triol, plasticizer I, and other components. Then, a crosslinking agent mixture is prepared as component B by compounding small molecule polyol, high molecule polyether polyol, calcium hydroxide, plasticizer II, catalyst, filler, and other components. Finally, components A and B are compounded under certain conditions to prepare a polyurethane sealant for cement concrete pavement joints. When applied to cement concrete pavement joints, this polyurethane sealant exhibits characteristics such as resistance to extreme weather conditions (high and low temperatures), aging resistance, high adhesion, and fast curing speed, thus overcoming various deficiencies of existing joint sealing materials.

[0013] The present invention also provides a method for preparing the polyurethane sealant for cement concrete pavement joints.

[0014] To achieve the above objectives, the present invention adopts the following technical solution: A polyurethane sealant for use at joints in cement concrete pavements, prepared from components A and B.

[0015] The ratio (mass ratio) of component A to component B is (30-40):(60-70).

[0016] Specifically, component A is the polyurethane prepolymer prepared from the first group of raw materials.

[0017] Specifically, the first group of raw materials includes polyether diol, polyether triol, isocyanate, and plasticizer I.

[0018] Specifically, the mass percentages of each raw material in the first group are: polyether diol 66-68%, polyether triol 9-11%, isocyanate 15-17%, and plasticizer I 5-7%.

[0019] Specifically, the polyether diol is designated as WANOL C2020.

[0020] Specifically, the polyether triol is designated as WANOL F3056D.

[0021] Specifically, the isocyanate is at least one of toluene diisocyanate, diphenylmethane diisocyanate, polymethylene polyphenyl diisocyanate, isophorone diisocyanate, and hexamethylene diisocyanate; preferably, the isocyanate is any one of toluene diisocyanate and diphenylmethane diisocyanate.

[0022] Specifically, the plasticizer I is an ester plasticizer. Preferably, the plasticizer I is at least one of dioctyl phthalate, diisononyl phthalate, and diisodecyl phthalate. More preferably, the plasticizer I is dioctyl phthalate.

[0023] Specifically, component B is a crosslinking agent mixture prepared from the second group of raw materials.

[0024] Specifically, the second group of raw materials includes small molecule polyols, high molecular weight polyether polyols, calcium hydroxide, water, dispersants, anti-settling agents, industrial salt, bentonite, plasticizer II, filler I, catalyst, and filler II.

[0025] Specifically, the mass percentage of each raw material in the second group is as follows: 1-2% small molecule polyol, 18-20% high molecule polyether polyol, 0.5-1.5% calcium hydroxide, 0.1-0.2% dispersant, 0.1-0.2% anti-settling agent, 0.1-0.2% industrial salt, 0.1-0.2% bentonite, 3-4% plasticizer II, 65-75% filler I, 0.5-2% catalyst, 0.1-0.2% filler II, and the balance is water.

[0026] Specifically, the small molecule polyol is glycerol or propylene glycol.

[0027] Specifically, the high molecular weight polyether polyol is at least one of polyether diol, polyether triol, polyether propylene glycol, and polyether glycerol. Preferably, the high molecular weight polyether polyol is polyether diol with the brand name WANOL C2020.

[0028] Specifically, the calcium hydroxide is industrial grade.

[0029] Specifically, the dispersant is a modified polyorganic carboxylic acid ammonium salt, such as any one of AKN-2100, DADDISPERSANT 6227, HY-165A, DP110, BYK-102, BYK-109 and BYK-169.

[0030] Specifically, the anti-settling agent is a surfactant-modified phosphate polymer, such as any one of AKN-7102, AKN-7020, AKN-7010, BYK-410, and DH-6900.

[0031] Specifically, the industrial salt is NaCl (industrially pure).

[0032] Specifically, the bentonite model is CARH-909.

[0033] Specifically, the plasticizer II is an ester plasticizer, preferably at least one of dioctyl phthalate, diisononyl phthalate and diisodecyl phthalate, and more preferably dioctyl phthalate.

[0034] Specifically, the filler I is at least one of carbon black, calcium carbonate, and barium sulfate.

[0035] Specifically, the catalyst is at least one of stannous octoate and dibutyltin dilaurate; preferably, the catalyst is dibutyltin dilaurate.

[0036] Specifically, the filler II is at least one of carbon black, calcium carbonate, and barium sulfate.

[0037] Furthermore, the present invention also provides a method for preparing the polyurethane sealant for cement concrete pavement joints, comprising the following steps: (1) According to the proportion of each raw material in the first group, add polyether diol, polyether triol, isocyanate and plasticizer I into the reactor, stir at room temperature for 30-120 min to obtain a mixture, and then carry out a polymerization reaction at a temperature of 80-90℃ for 10-12 h to obtain polyurethane prepolymer, which is component A. (2) According to the proportion of each raw material in the second group, mix the small molecule polyol, high molecule polyether polyol, water, dispersant, anti-settling agent, industrial salt, bentonite, plasticizer II and filler II at room temperature for 10-30 min, then add calcium hydroxide and mix at room temperature for 20-40 min, then add filler I and mix at room temperature for 10-30 min, and finally add catalyst and mix at room temperature for 5-15 min to obtain the crosslinking agent mixture, which is component B; (3) When using, mix components A and B according to a certain ratio, stir at high speed (180~200r / min) for 1~3 minutes at room temperature to make polyurethane sealant.

[0038] Specifically, in step (3), the mass ratio of group A to group B is (30~35):(60~70).

[0039] Furthermore, the present invention also provides the application of the polyurethane sealant for cement concrete pavement joints as a road crack sealing material.

[0040] Specifically, the polyurethane sealant for cement concrete pavement joints is used as a filler material for cement concrete pavement joints.

[0041] Furthermore, the present invention also provides the application of the polyurethane sealant for cement concrete pavement joints in the waterproofing construction of building floor slabs.

[0042] Furthermore, the present invention also provides the application of the polyurethane sealant for cement concrete pavement joints in the waterproofing construction of concrete surfaces.

[0043] Furthermore, the present invention also provides the application of the polyurethane sealant for cement concrete pavement joints in sealing and waterproofing joints of highways and concrete bridges.

[0044] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The polyurethane sealant provided by this invention is a new cement concrete pavement grouting material that can withstand extreme weather conditions of high and low temperatures. It has the characteristics of aging resistance, high adhesion and fast curing speed, and can solve various shortcomings of existing grouting materials.

[0045] 2. This invention increases the adhesion between new and old materials by adding a special substance (industrial salt) to the polyurethane sealant material. This makes it possible to repair and maintain joints in cement concrete pavements using the polyurethane sealant material, thereby reducing joint maintenance costs, improving efficiency, and being environmentally friendly.

[0046] 3. This invention improves the resilience (intercalation resistance) of the material by adjusting the amount of plasticizer used. The main principle is to change the elastic material from being filled with air bubbles to being filled with tiny droplets, thereby resolving the contradiction between the modulus and elasticity of the polyurethane sealant material.

[0047] 4. This invention utilizes a molecular-level antifreeze system composed of glycerol, water, and sodium chloride to give the material better low-temperature resistance. It can solve the problem of tensile cracking under extreme temperatures (a key factor in material tearing is the failure of its anti-cracking performance at extreme or prolonged low temperatures).

[0048] 5. The unique structural system of the polyurethane sealant material described in this invention allows the material surface to remain moist and adherent. Experimental verification has shown that during use, the polyurethane sealant material adsorbs road dust, especially carbon black-containing rubber dust from tire wear, forming a protective film that greatly improves and enhances the material's durability and weather resistance. Attached Figure Description

[0049] Figure 1 Photos of pouring and bonding two types of grouting materials, old and new; Figure 1 The top left image shows old sealant that has hardened in a container. Figure 1The top right image shows the new crack sealant being poured into the same container as the old sealant. Figure 1 The lower image shows photographs of the old and new crack sealing materials after curing. Here, the crack sealing material refers to the polyurethane sealant described in Example 1. Figure 2 A tensile test diagram showing the bonding of new and old sealant materials together; Figure 2 The image in the middle left shows the new and old crack sealant materials in their unstretched states. Figure 2 The middle image shows the state of the new and old crack sealing materials after being stretched to a certain extent. Figure 2 The middle right image shows the state of the new and old crack sealing materials under further stretching. Figure 3 This is a micrograph of the industrial salt used in this invention. Detailed Implementation

[0050] To make the technical objectives, technical solutions, and beneficial effects of the present invention clearer, the technical solutions of the present invention will be further described below in conjunction with specific embodiments. However, the embodiments are intended to explain the present invention and should not be construed as limiting the present invention. Where no specific technology or conditions are specified in the embodiments, the technology or conditions described in the literature in the field or the product manual shall apply.

[0051] In the following examples, room temperature or normal temperature refers to 25±5℃. Example 1

[0052] A polyurethane sealant for joints in cement concrete pavements, prepared from component A and component B; Specifically, the composition and preparation methods of components A and B are as follows: 1.1 Component A is a polyurethane prepolymer prepared from the components in Table 1.

[0053] Table 1.

[0054]

[0055] Component A is prepared from 210g of polyether diol, 31.5g of polyether triol, 50g of benzene-containing polyisocyanate and 20g of ester plasticizer.

[0056] The polyether diol is WANOL C2020 produced by Wanhua Chemical Group, with a molecular weight of 2000, 2 hydroxyl groups, and a total -OH equivalent of 0.085; the polyether triol is WANOL F 3056D produced by Wanhua Chemical Group, with a molecular weight of 3000, 3 hydroxyl groups, and a total -OH equivalent of 0.2415. The benzene-containing polyisocyanate is toluene diisocyanate (T-80) produced by Wanhua Chemical Group, with a molecular weight of 174, 2 hydroxyl groups, and an -NCO equivalent of 0.5747.

[0057] The ratio of the total molar number of hydroxyl groups in polyether diols and polyether triols to the molar number of isocyanate groups in benzene-containing polyisocyanates is 1:2.38.

[0058] The mass fraction of the ester plasticizer in component A is 6.42%.

[0059] 1.2 The method for preparing polyurethane prepolymers using the components in Table 1 includes the following steps: Polyether diol, polyether triol, benzene-containing polyisocyanate and ester plasticizer are added to a reaction vessel and stirred at room temperature for 60 minutes to obtain a mixture. Then, the mixture is polymerized at 90°C for 12 hours to obtain a polyurethane prepolymer, which is used as component A of the sealant.

[0060] 1.3 The prepared polyurethane prepolymer was analyzed, and the results are shown in Table 2: Table 2.

[0061]

[0062] Among them, the molar ratio of functional groups = -NCO / -OH = 2.38 (high production safety factor).

[0063] 2.1 Component B is a crosslinking agent mixture prepared from the components in Table 3.

[0064] Table 3.

[0065]

[0066] Component B is prepared from 190g of high molecular weight polyether polyol, 15g of low molecular weight polyol, 20g of water, 10g of calcium hydroxide, 35g of plasticizer, 1.7g of bentonite, 1g of industrial salt, 711g of filler, 1.7g of dispersant, 1.6g of anti-settling agent and 13g of catalyst.

[0067] 2.2 The method for preparing the crosslinking agent mixture using the components in Table 3 is as follows: 1) Add the raw materials 1, 2, 3, 5, 6, 7, 8, 9, and 12 shown in Table 3 to a clean dispersion vessel and disperse at high speed for 20 minutes.

[0068] 2) Then add raw material 4 as shown in Table 3 and disperse at high speed for 30 minutes.

[0069] 3) Add raw material 10 as shown in Table 3 and continue to disperse for 20 minutes. Then add raw material 11 as shown in Table 3 and disperse for 10 minutes.

[0070] 4) Stop stirring to obtain the crosslinking agent mixture, which is component B. Seal and store for later use.

[0071] The requirements for component B during preparation are: uniform color and smooth, slurry-like consistency.

[0072] 3.1 Mix components A and B at a ratio (mass ratio) of 35:65, stir at high speed (200 r / min) for 2 minutes at room temperature to prepare polyurethane sealant, and perform performance testing. The various indicators in the "Technical Specifications for Construction of Cement Concrete Pavement of Highway" (JTG / T F30-2014) are shown in Table 4.

[0073] Table 4.

[0074]

[0075] 4.1 The actual test results of the polyurethane sealant prepared in Example 1 are shown in Table 5.

[0076] Table 5.

[0077]

[0078] As can be seen from Table 5, the polyurethane sealant prepared in Example 1 of this invention meets or exceeds the quality standards for polyurethane room temperature construction joint fillers in the "Technical Specifications for Construction of Cement Concrete Pavement of Highway" (JTG / T F30-2014), and has good performance.

[0079] 5.1 Compared with the prior art, the advantages of the present invention are as follows: 5.1.1 In the preparation process of component B of the present invention, high molecular weight polyether polyol, glycerol, calcium hydroxide and water are dispersed together in a certain proportion. Under this alkaline condition, the reaction rate of the raw materials can be arbitrarily adjusted by adjusting the amount of catalyst, thereby achieving rapid reaction (the time required for material reaction and molding can be arbitrarily adjusted from a few minutes to a few hours), which greatly shortens the curing time after material construction and meets the needs of modern highway maintenance construction.

[0080] 5.1.2 In the preparation process of component B of the present invention, glycerol reacts with calcium hydroxide to generate calcium glycerol, which serves as a heat stabilizer. Studies on heat stability and aging kinetics show that the heat stability time of the polyurethane sealant of the present invention is increased by about 10 times after the addition of calcium glycerol.

[0081] 5.1.3 The advantage of using calcium glycerol as a heat stabilizer in component B of the present invention is: 1) Improve material stability: Heat stabilizers can stabilize the performance and properties of materials at high temperatures, preventing materials from decomposing, deforming, or losing their original properties.

[0082] 2) Enhance the heat resistance of materials: Heat stabilizers can enhance the heat resistance of materials, enabling them to maintain their original performance and characteristics at high temperatures.

[0083] 3) Extend the service life of materials: Heat stabilizers can extend the service life of materials, reduce aging and damage, thereby reducing the maintenance and replacement costs of materials.

[0084] 4) Furthermore, calcium glycerol, as a complex, has calcium ions that effectively adsorb and absorb the carbon dioxide generated during the mixing and reaction of components A and B in this invention, resulting in a denser sealant structure and better physical properties. Because of this effect, heating and vacuum dehydration of the raw materials is unnecessary during the production of components A and B, making the production process more energy-efficient and environmentally friendly.

[0085] 5) In this invention, the molecular-level antifreeze system composed of glycerol, water and sodium chloride is uniformly distributed in the sealant, which can improve the low-temperature resistance of the sealant.

[0086] 6) In the preparation process of the polyurethane sealant described in this invention, a unique reaction system is formed by mixing polyurethane prepolymer and crosslinking agent. After the polyurethane sealant is formed, the product surface has a unique and lasting adhesiveness, which can adsorb road rubber tire powder and cement dust, etc., thereby forming a very reliable protective barrier for the sealant material and greatly improving the light and heat aging resistance of the sealant material (the sealant still has good elasticity 5-8 years after construction).

[0087] 7) In the preparation process of the polyurethane sealant described in this invention, the adhesion and elongation of the material to metal are improved through the use of NaCl in component B. NaCl is a typical ionic crystal. + and Cl - They are regularly arranged in three-dimensional space through ionic bonds; there are no molecules. Cl - Na forms a lattice packing according to the face-centered cubic closest packing method. + Filling Cl - In the octahedral voids, Na + and Cl - Through ionic bonding, a three-dimensional network structure that extends wirelessly is formed, which not only extends and enhances the material, but also provides better adhesion between the material and the metal during the construction of road and bridge expansion joints by ionic bonding.

[0088] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that no industrial salt was added to component B (and water was used to make up the total mass of component B), otherwise it is the same as Example 1.

[0089] Performance testing (a) Adhesion performance between new and old materials The term "used material" here refers to the polyurethane sealant described in Example 1 that has been applied for a period of time, or the polyurethane sealant described in Example 1 that has been aged under laboratory conditions. The aging treatment method is described in item 12 of Table 4 (JT / T203, GB / T13477.10).

[0090] The polyurethane sealant of this invention contains a special substance in component B: industrial salt (mainly NaCl, the microstructure of which is shown in the figure). Figure 3 As shown), it can create a new bond between the new and old grouting materials. This is a unique property of the polyurethane sealant of this invention, which fundamentally guarantees a perfect bond between the two types of grouting materials, making re-grouting and renovation possible. The method of pouring and bonding the new and old grouting materials is as follows: Figure 1 As shown, this simulates a secondary construction scenario under actual conditions. Figure 1 The top left image shows old sealant that has hardened in a container. Figure 1 The top right image shows the new crack sealant being poured into the same container as the old sealant. Figure 1 The lower image shows photographs of the old and new sealant materials after curing. Here, the sealant material refers to the polyurethane sealant described in Example 1.

[0091] Performance testing method design: Comparative Experiment 1: Tensile test was conducted after bonding with the polyurethane sealant containing industrial salt as described in Example 1 (tested after 24 hours of curing). Comparative Experiment 2: The same post-bonding tensile test as in Comparative Experiment 1 was conducted using the material described in Comparative Example 1 without the addition of industrial salt.

[0092] See tensile test Figure 2 Specifically, during the experiment, Figure 1 After curing, the old and new crack sealing materials were cut into strips for testing. Figure 2 The image in the middle left shows the new and old crack sealant materials in their unstretched states. Figure 2 The middle image shows the state of the new and old crack sealing materials after being stretched to a certain extent. Figure 2 The image on the right shows the state of the new and old sealant materials under further stretching.

[0093] The comparative experiments above show that stretching the bonded polyurethane sealant described in Example 1 by 200% and holding it for 24 hours can prevent the bonded surfaces from separating. (Tested according to the method in the "Technical Specifications for Construction of Cement Concrete Pavement of Highway" (JTG / T F30-2014)).

[0094] Further testing revealed that, following the above testing methods, stretching the new and old sealant materials to a certain extent and maintaining them for 5 hours, one day, or one week all resulted in the bonding surfaces remaining intact without pulling apart or cracking.

[0095] In actual construction, removing the old sealant from the expansion joints of highway viaducts is extremely difficult, time-consuming, and labor-intensive. However, as can be seen from this invention, the new and old sealant materials exhibit excellent adhesion. In practical applications, the old sealant material can be applied directly without removal, demonstrating good bonding, weather resistance, and workability.

[0096] (II) The principle of the negative temperature crack resistance of the polyurethane sealant described in this invention The water, industrial salt, glycerin, and polyether polyol in the polyurethane sealant are reactants that participate in the material curing reaction. The unreacted material forms a micro-antifreeze system embedded between molecules, thereby improving the material's resistance to cracking at low temperatures. This results in exceptionally good low-temperature performance, enabling the material to maintain its flexibility for extended periods in the low-temperature environments of northern my country, ensuring it does not crack due to low temperatures.

[0097] Finally, it should be noted that the above embodiments are only for illustration and not for limiting the technical solutions of the present invention. Any equivalent substitutions, modifications or partial substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A polyurethane sealant for joints in cement concrete pavements, characterized in that, It is prepared from components A and B; The mass ratio of component A to component B is (30-40):(60-70).

2. The polyurethane sealant for joints in cement concrete pavements according to claim 1, characterized in that, Component A is a polyurethane prepolymer prepared from the first group of raw materials; The first group of raw materials includes polyether diol, polyether triol, isocyanate and plasticizer I; Component B is a crosslinking agent mixture prepared from the second group of raw materials; The second group of raw materials includes small molecule polyols, high molecule polyether polyols, calcium hydroxide, water, dispersants, anti-settling agents, industrial salt, bentonite, plasticizer II, filler I, catalyst, and filler II.

3. The polyurethane sealant for joints in cement concrete pavements according to claim 1, characterized in that, The mass percentages of each raw material in the first group are: polyether diol 66-68%, polyether triol 9-11%, isocyanate 15-17%, and plasticizer I 5-7%; The mass percentages of the raw materials in the second group are as follows: 1-2% small molecule polyol, 18-20% high molecule polyether polyol, 0.5-1.5% calcium hydroxide, 0.1-0.2% dispersant, 0.1-0.2% anti-settling agent, 0.1-0.2% industrial salt, 0.1-0.2% bentonite, 3-4% plasticizer II, 65-75% filler I, 0.5-2% catalyst, 0.1-0.2% filler II, and the balance is water.

4. The polyurethane sealant for joints in cement concrete pavements according to claim 1, characterized in that, The polyether diol is designated as WANOL C2020. The polyether triol is designated as WANOL F3056D. The isocyanate is at least one of toluene diisocyanate, diphenylmethane diisocyanate, polymethylene polyphenyl diisocyanate, isophorone diisocyanate, and hexamethylene diisocyanate; The plasticizer I is at least one of dioctyl phthalate, diisononyl phthalate, and diisodecyl phthalate.

5. The polyurethane sealant for joints in cement concrete pavements according to claim 1, characterized in that, The small molecule polyol is glycerol or propylene glycol; The high molecular weight polyether polyol is at least one of polyether diol, polyether triol, polyether propylene glycol, and polyether glycerol; The dispersant is a modified polyorganic carboxylic acid ammonium salt, specifically any one of AKN-2100, DAD DISPERSANT 6227, HY-165A, DP110, BYK-102, BYK-109, and BYK-169; the anti-settling agent is a surfactant-modified phosphate polymer, specifically any one of AKN-7102, AKN-7020, AKN-7010, BYK-410, and DH-6900; the plasticizer II is at least one of dioctyl phthalate, diisononyl phthalate, and diisodecyl phthalate. The filler I is at least one of carbon black, calcium carbonate and barium sulfate; The catalyst is at least one of stannous octoate and dibutyltin dilaurate; The filler II is at least one of carbon black, calcium carbonate, and barium sulfate.

6. A method for preparing the polyurethane sealant for cement concrete pavement joints as described in any one of claims 1-5, characterized in that, Includes the following steps: (1) According to the proportion of each raw material in the first group, add polyether diol, polyether triol, isocyanate and plasticizer I into the reactor, stir at room temperature for 30-120 min to obtain a mixture, and then carry out a polymerization reaction at a temperature of 80-90℃ for 10-12 h to obtain polyurethane prepolymer, which is component A. (2) According to the proportion of each raw material in the second group, mix the small molecule polyol, high molecule polyether polyol, water, dispersant, anti-settling agent, industrial salt, bentonite, plasticizer II and filler II at room temperature for 10-30 min, then add calcium hydroxide and mix at room temperature for 20-40 min, then add filler I and mix at room temperature for 10-30 min, and finally add catalyst and mix at room temperature for 5-15 min to obtain the crosslinking agent mixture, which is component B; (3) Mix component A and component B according to a certain ratio and stir for 1 to 3 minutes at room temperature to make polyurethane sealant.

7. The preparation method according to claim 6, characterized in that, In step (3), the mass ratio of group A to group B is (30~35):(60~70).

8. The use of the polyurethane sealant for cement concrete pavement joints as described in any one of claims 1-5 as a road crack sealing material.

9. The application according to claim 8, characterized in that, The polyurethane sealant used for joints in cement concrete pavements is used as a filler material for cement concrete pavements.

10. The application of the polyurethane sealant for cement concrete pavement joints as described in any one of claims 1-5 in the waterproofing construction of concrete surfaces.

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