An elastic concrete for expansion joints and its preparation method

Abstract

The application relates to the technical field of road and bridge materials, and discloses elastic concrete for expansion joints and a preparation method thereof, which comprises the following components: A component, a modified titanium dioxide / isocyanate end-capped amino polyether prepolymer compound, which is made of isocyanate modified titanium dioxide and isocyanate end-capped amino prepolymer; B component, an amino-terminated polyether and an auxiliary additive; and C component, mixed stone. The mechanical properties and toughness of the elastic concrete are improved, and the material is endowed with good durability and ultraviolet resistance.

Description

Technical Field

[0001] This invention relates to the field of road and bridge materials technology, specifically to an elastic concrete for expansion joints and its preparation method. Background Technology

[0002] Bridge expansion joint repair materials are mainly divided into two categories: cement concrete and epoxy resin concrete. Cement concrete has disadvantages such as long curing time, high rigidity but lack of toughness, and under conditions of excessive load, rain erosion, and extreme heat or cold, it suffers from durability problems such as surface delamination, honeycombing, structural deformation, and exposed rebar, seriously threatening the safety and driving comfort of bridges and resulting in a short service life. Epoxy resin concrete lacks toughness and is prone to aging under strong ultraviolet light, leading to surface cracking and decreased strength.

[0003] Chinese patent document CN114873976B discloses a polyurethane elastic concrete and its preparation method, which is prepared from raw materials including carbon nanomaterials-polyisocyanate prepolymer composite components and plasticizers; the carbon nanomaterials-polyisocyanate prepolymer composite components are prepared by mixing raw materials including carbon nanomaterials, polyisocyanates and polyols.

[0004] Chinese patent document CN107829344B discloses a super-strong composite seal material for highways and its construction application. The super-strong composite seal material for highways includes a bonding layer material and crushed stone, and also includes an energy-absorbing spray layer material; the energy-absorbing spray layer, bonding layer and crushed stone layer are arranged sequentially from bottom to top; the energy-absorbing spray layer material is made of the following raw materials: polyurea prepolymer, nano-graphene, chain extender, coupling agent, defoamer and filler; the polyurea prepolymer is made of the following raw materials: isocyanate and amino compound.

[0005] The existing technology has the following shortcomings: Although concrete materials in the existing technology have good elastic deformation capacity and fatigue crack resistance, they are still prone to surface cracking and strength reduction in summer or high-altitude areas. Summary of the Invention

[0006] To address the technical problems of easy cracking and strength reduction in elastic concrete for expansion joints, this invention provides an elastic concrete for expansion joints, characterized by comprising: Component A: a modified titanium dioxide / isocyanate-terminated amino-terminated polyether prepolymer composite, made of isocyanate-modified titanium dioxide and isocyanate-terminated amino-terminated prepolymer; Component B: amino-terminated polyether and auxiliary additives; Component C: mixed aggregate.

[0007] Preferably, the weight ratio of components A, B, and C is 100:20-30:500-1000.

[0008] Preferably, the isocyanate is at least one selected from hexamethylene diisocyanate, isophorone diisocyanate, toluene diisocyanate, and diphenylmethane-4,4'-diisocyanate.

[0009] Preferably, the amino-terminated polyether is at least one of amino-terminated polyether D-230, amino-terminated polyether AMD-2000, amino-terminated polyether ZD-123, amino-terminated polyether ZD-140, amino-terminated polyether ZD-143, amino-terminated polyether ZD-1200, and amino-terminated polyether ZD-1500.

[0010] Preferably, component C: the mixed stone includes basalt, rubber powder, and mineral powder, with the basalt having a dense gradation of 0-10mm and the rubber powder having a mesh size of 30-60.

[0011] Preferably, the titanium dioxide is made of nano-sized titanium dioxide particles with a size range of 1 nm to 100 nm.

[0012] Preferably, the auxiliary additives include: antioxidants, plasticizers, chain extenders, and defoamers.

[0013] Preferably, the antioxidant is at least one of N-phenyl-α-naphthylamine, antioxidant D, antioxidant DNP, and antioxidant AW.

[0014] Preferably, the plasticizer is at least one of di(2-ethylhexyl) phthalate (DEHP), butyl oleate (BO), triphenyl phosphate (TPP), and dioctyl sebacate (DEHS); the chain extender is at least one of 3,5-dimethylthiotoluenediamine, di-sec-butylaminodiphenylmethane, and diethyltoluenediamine; and the defoamer is at least one of defoamer DF-3114, silicone defoamer DF-2854, and defoamer DF-2417.

[0015] A method for preparing elastic concrete for expansion joints:

[0016] Step 1: Weigh 10-20 parts of titanium dioxide and pre-dry it in an oven. Dissolve it in N,N dimethylacetamide solvent by ultrasonication. Add 20-40 parts of isocyanate dropwise to the reaction solution and stir continuously at room temperature. The isocyanate groups are attached to the surface of titanium dioxide. Centrifuge and dry to obtain isocyanate-modified nano titanium dioxide particles.

[0017] Step 2: Weigh 40-50 parts of amino-terminated polyether and dehydrate it at high temperature, then cool it to room temperature; weigh 100 parts of isocyanate, heat it, add the amino-terminated polyether dropwise and stir continuously to obtain isocyanate-terminated amino-terminated prepolymer; weigh 3-5 parts of isocyanate-modified nano-titanium dioxide particles, add them to 15-30 parts of plasticizer, ultrasonically disperse them, and add them to the isocyanate-terminated amino-terminated prepolymer. Stir and mix evenly at room temperature to obtain component A;

[0018] Step 3: Weigh 60-70 parts of amino-terminated polyether, 10-20 parts of plasticizer, 3-5 parts of chain extender, and 1-3 parts of defoamer, and stir and mix them evenly at room temperature to obtain component B.

[0019] Step 4: Mix basalt, mineral powder, and rubber granules evenly to obtain component C. Keep component C dry before use.

[0020] Step 5: Mix component A and component B at a weight ratio of 100:20-30 and stir for 1 min to 3 min to obtain a uniform binder.

[0021] Step 6: Add 500-1000 parts of component C to the mixed binder and mix for 1-3 minutes to obtain elastic concrete.

[0022] The present invention has the following beneficial effects:

[0023] 1. The elastic concrete prepared by this invention not only improves the mechanical properties and toughness of expansion joints, but also endows them with better durability and UV resistance. Nano-sized titanium dioxide, due to its small particle size and high activity, can both reflect and scatter ultraviolet rays, as well as absorb them, thus providing stronger UV blocking capabilities. By improving the UV resistance of expansion joints to resist aging, surface cracking and strength reduction are avoided, further extending their service life.

[0024] 2. This invention incorporates a reactive activating antioxidant. This not only further improves the anti-aging properties of expansion joints, but also allows the antioxidant to react with isocyanates in the system, and the modified titanium dioxide to react with terminal amino polyethers in the system. Both substances can be uniformly dispersed in the system, enhancing its performance. Under the synergistic effect of the antioxidant and modified titanium dioxide, a polyurea network structure is jointly constructed. The antioxidant acts as a large-structure hard segment phase, enabling better microphase separation in the elastomer, further endowing the material with good toughness, thermal stability, and durability.

[0025] 3. In this invention, the ratio of terminal amino polyether to isocyanate can be controlled, and the synthesis method used is easy to operate and simple to process. Furthermore, no organometallic compounds or amine catalysts are added during the reaction to prepare high-toughness and high-strength polyurea elastomers. Attached Figure Description

[0026] Figure 1 This is a scanning electron microscope image of the present invention;

[0027] Figure 2 This is a scanning electron microscope image of the present invention.

[0028] 1. The reference numerals in the accompanying drawings of the instruction manual include: titanium dioxide 1. Detailed Implementation

[0029] The following detailed description illustrates the specific implementation method:

[0030] 1. Example 1

[0031] An elastic concrete for expansion joints includes component A: a modified titanium dioxide / isocyanate-terminated amino-terminated polyether prepolymer composite and a plasticizer, wherein the modified titanium dioxide / isocyanate-terminated amino-terminated polyether prepolymer composite is made of isocyanate-modified titanium dioxide and isocyanate-terminated amino-terminated prepolymer; component B: amino-terminated polyether, antioxidant, plasticizer, chain extender, and defoamer; component C: mixed aggregate including limestone, rubber powder, and mineral powder; the weight ratio of components A, B, and C is 100:20-30:500-1000.

[0032] The isocyanate is at least one of hexamethylene diisocyanate, isophorone diisocyanate, toluene diisocyanate, and diphenylmethane-4,4'-diisocyanate.

[0033] The amino-terminated polyether is at least one of the following: amino-terminated polyether D-230, amino-terminated polyether AMD-2000, amino-terminated polyether ZD-123, amino-terminated polyether ZD-140, amino-terminated polyether ZD-143, amino-terminated polyether ZD-1200, and amino-terminated polyether ZD-1500.

[0034] The limestone particle size is 3 mm - 5 mm, and the rubber powder is 30-60 mesh.

[0035] Titanium dioxide is made of nano-sized titanium dioxide particles with a size range of 1 nm to 100 nm.

[0036] The antioxidant is at least one of N-phenyl-α-naphthylamine, antioxidant D, antioxidant DNP, and antioxidant AW.

[0037] The plasticizer is at least one of di(2-ethylhexyl) phthalate (DEHP), butyl oleate (BO), triphenyl phosphate (TPP), and dioctyl sebacate (DEHS); the chain extender is at least one of 3,5-dimethylthiotoluenediamine, di-sec-butylaminodiphenylmethane, and diethyltoluenediamine; and the defoamer is at least one of defoamer DF-3114, silicone defoamer DF-2854, and defoamer DF-2417.

[0038] A method for preparing elastic concrete for expansion joints, step 1: weigh 10 parts of nano-titanium dioxide particles and pre-dry them in an oven at 120°C for 1 hour. Dissolve them in 100 parts of NN dimethylacetamide (DMA) solvent by ultrasonication. Add 35 parts of hexamethylene diisocyanate dropwise to the reaction solution. After stirring continuously at room temperature for 2 hours, the isocyanate groups have been successfully attached to the surface of nano-titanium dioxide. After centrifugation and drying, isocyanate-modified nano-titanium dioxide particles (TiO2-NCO) are obtained.

[0039] Step 2: Weigh 45 parts of end-amino polyether D-230 and dehydrate it at 120℃ for 2 hours, then cool it to room temperature; weigh 100 parts of hexamethylene diisocyanate and heat it to 80℃, then add end-amino polyether D-230 dropwise and stir continuously for 1 hour to obtain isocyanate-capped end-amino prepolymer; weigh 5 parts of TiO2-NCO and add it to 15 parts of butyl oleate BO and ultrasonically disperse for 1 hour, then add it to the isocyanate-capped end-amino prepolymer and stir at room temperature for 0.5 hours to mix evenly to obtain component A.

[0040] Step 3: Weigh 60 parts of amino-terminated polyether D-230, 10 parts of di(2-ethylhexyl) phthalate DEHP, 3 parts of 3,5-dimethylthiotoluene diamine, and 1.5 parts of defoamer DF-3114. Stir at room temperature for 1 hour to mix evenly to obtain component B.

[0041] Step 4: Densely graded basalt (less than 10 mm), mineral powder, and 60-mesh rubber granules are mixed and stirred evenly to obtain component C. Keep component C dry before use.

[0042] Step 5: Mix component A and component B at a weight ratio of 100:20 and stir for 3 minutes to obtain a uniform binder.

[0043] Step 6: Add 800 parts of component C to the mixed binder and mix for 3 minutes to obtain durable, high-toughness elastic concrete.

[0044] 2. Example 2

[0045] A method for preparing elastic concrete for expansion joints includes the following steps: Step 1: Weigh 10 parts of nano-titanium dioxide particles and pre-dry them in an oven at 120°C for 1 hour. Dissolve them in 100 parts of NN dimethylacetamide (DMA) solvent by ultrasonication. Add 40 parts of isophorone diisocyanate and toluene diisocyanate dropwise to the reaction solution. After stirring continuously at room temperature for 2 hours, the isocyanate groups have been successfully attached to the surface of the nano-titanium dioxide. After centrifugation and drying, isocyanate-modified nano-titanium dioxide particles (TiO2-NCO) are obtained.

[0046] Step 2: Weigh 40 parts of amino-terminated polyether D-230 and dehydrate it at 120℃ for 2 hours, then cool it to room temperature; weigh 5 parts of TiO2-NCO and add it to 15 parts of butyl oleate BO for ultrasonic dispersion for 1 hour, then add it to amino-terminated polyether D-230 and stir at room temperature for 0.5 hours to mix evenly to obtain component A.

[0047] Step 3: Weigh 60 parts of amino-terminated polyether D-230, 10 parts of butyl oleate BO, 3 parts of di-sec-butylaminodiphenylmethane, and 1.5 parts of defoamer DF-2417. Stir at room temperature for 1 hour to mix evenly to obtain component B.

[0048] Step 4: Densely graded basalt (less than 10 mm), mineral powder, and 60-mesh rubber granules are mixed and stirred evenly to obtain component C. Keep component C dry before use.

[0049] Step 5: Mix component A and component B at a weight ratio of 100:20 and stir for 3 minutes to obtain a uniform binder.

[0050] Step 6: Add 800 parts of component C to the mixed binder and mix for 3 minutes to obtain durable, high-toughness elastic concrete.

[0051] As shown in Table 1, the mechanical strength of the present invention is greater than 50 MPa, the bond strength between the expansion joint and the base surface (25℃) is 6.8 MPa, the low-temperature failure strain (-10℃) is >50000 μm, and the durability index is 99.1%. It not only improves the mechanical properties and toughness of elastic concrete, but also makes the repaired expansion joint have better durability, UV resistance and anti-aging properties.

[0052] Test Project Example 1 Test Results Example 2 Test Results Mechanical strength, MPa >50 35 Bond strength to substrate (25℃), MPa 6.8 3.6 Low-temperature failure strain (-10℃), μm >50000 >20000 Durability index, % 99.1 97.5 Mechanical strength retention rate (accelerated UV aging for 720 hours), % ＞90 ＞90

[0053] From the modified scanning electron microscope of this invention Figure 1 and Figure 2 As can be seen from the figure, the bright spots on the substrate are titanium dioxide 1. Titanium dioxide 1 can be uniformly dispersed in the base of the material without agglomeration, thus demonstrating the UV resistance of the present invention.

[0054] The above descriptions are merely embodiments of the present invention. Commonly known structures and characteristics are not described in detail here. Those skilled in the art are aware of all common technical knowledge in the field prior to the application date or priority date, are aware of all existing technologies in that field, and have the ability to apply conventional experimental methods prior to that date. Those skilled in the art can, under the guidance of this application, improve and implement this solution in combination with their own capabilities. Some typical known structures or methods should not be obstacles for those skilled in the art to implement this application. It should be noted that those skilled in the art can make several modifications and improvements without departing from the structure of the present invention. These should also be considered within the scope of protection of the present invention, and will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. An elastic concrete for expansion joints, characterized in that, The composition comprises A component: modified titanium dioxide / isocyanate-terminated amino polyether prepolymer complex, which is made of isocyanate-modified titanium dioxide and isocyanate-terminated amino prepolymer obtained by introducing isocyanate groups into the surface of titanium dioxide; B component: amino-terminated polyether and auxiliary additives; C component: mixed stone.

2. The elastic concrete for expansion joints according to claim 1, characterized in that: The weight ratio of A, B and C components is 100:20-30:500-1000.

3. The elastic concrete for expansion joints according to claim 2, characterized in that: The isocyanate is at least one of hexamethylene diisocyanate, isophorone diisocyanate, toluene diisocyanate and diphenylmethane-4,4'-diisocyanate.

4. The elastic concrete for expansion joints according to any one of claims 1 to 3, characterized in that: The amino-terminated polyether is at least one of amino-terminated polyether D-230, amino-terminated polyether AMD-2000, amino-terminated polyether ZD-123, amino-terminated polyether ZD-140, amino-terminated polyether ZD-143, amino-terminated polyether ZD-1200 and amino-terminated polyether ZD-1500.

5. The elastic concrete for expansion joints according to claim 4, characterized in that: The mixed stone comprises basalt, rubber powder and mineral powder, the basalt is 0-10 mm dense gradation, and the rubber powder is 30-60 mesh.

6. The elastic concrete of expansion joint according to claim 5, characterized in that: The titanium dioxide is nano titanium dioxide particles with a size range of 1 nm-100 nm.

7. Elastic concrete for expansion joints according to any one of claims 5 and 6, characterized in that: The auxiliary additives include anti-aging agents, plasticizers, chain extenders and defoamers.

8. The elastic concrete of expansion joint according to claim 7, characterized in that: The anti-aging agent is at least one of N-phenyl-α-naphthylamine, anti-aging agent D, anti-aging agent DNP and anti-aging agent AW.

9. The elastic concrete of expansion joint according to claim 8, characterized in that: The plasticizer is at least one of di(2-ethylhexyl) phthalate DEHP, butyl oleate BO, triphenyl phosphate TPP and dioctyl sebacate DEHS; the chain extender is at least one of 3,5-dimethylthio toluene diamine, bis-sec-butylamine diphenyl methane and diethyl toluene diamine; and the defoamer is at least one of defoamer DF-3114, silicone defoamer DF-2854 and defoamer DF-2417.

10. The method for preparing the elastic concrete of the expansion joint according to any one of claims 1-9, characterized in that: Step 1: 10-20 parts of titanium dioxide are weighed and pre-dried in an oven, dissolved in N-N dimethylacetamide solvent by ultrasonic, 20-40 parts of isocyanate is added dropwise into the reaction solution, continuously stirred at room temperature, isocyanate groups are introduced into the surface of titanium dioxide, centrifuged and dried to obtain isocyanate-modified nano titanium dioxide particles; Step 2: 40-50 parts of amino-terminated polyether is weighed and dehydrated at high temperature, and then cooled to room temperature; 100 parts of isocyanate is heated, then the amino-terminated polyether is added dropwise and continuously stirred to obtain an isocyanate-terminated amino prepolymer; 3-5 parts of isocyanate-modified nano titanium dioxide particles are added into 15-30 parts of plasticizer and ultrasonically dispersed, and then added into the isocyanate-terminated amino prepolymer and stirred at room temperature to obtain the A component; Step 3: 60-70 parts of amino-terminated polyether, 10-20 parts of plasticizer, 3-5 parts of chain extender and 1-3 parts of defoamer are weighed and stirred at room temperature to obtain the B component; Step 4: basalt, mineral powder and rubber particles are mixed and stirred uniformly to obtain the C component, which is kept dry before use. Step 5, mix and stir A component and B component according to the weight ratio of 100:20-30 for 1 min~3 min, to obtain a uniform cementing material; Step 6, add 500 parts-1000 parts of C three-component to the mixed cementing material, mix and stir for 1 min~3 min, to obtain the elastic concrete.

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