Phase-change and anti-freezing composite aggregate and preparation method thereof

Abstract

The preparation method comprises the following steps: taking sodium chloride as a core material and gelatin as a wall material, fully mixing a gelatin solution and a sodium chloride solution according to a mass ratio of the core material to the wall material of (2-10): 1 to obtain a mixed solution, and performing spray drying on the mixed solution to obtain a salt storage microcapsule; mixing liquid epoxy resin, polyethylene glycol with the molecular weight of 200-1000 and salt storage microcapsules according to the mass ratio of 2: (1-3): (1-3), adding an epoxy curing agent, uniformly stirring to obtain a mixture, finally pouring the prepared mixture into a mold, drying, curing and crushing to obtain the phase-change and anti-freezing composite aggregate which takes the epoxy resin as a matrix and the polyethylene glycol and the salt storage microcapsules as fillers. The composite aggregate has the capability of adjusting the pavement temperature, is high in strength and good in durability, has the functions of low-temperature phase change, anti-freezing and the like, and can be doped into an asphalt mixture to replace part of the aggregate to play a role in bearing.

Description

Technical Field

[0001] The invention relates to the field of pavement maintenance materials, and in particular to a phase-change, anti-icing composite aggregate and a preparation method thereof. Background Art

[0002] In winter, ice and snow easily accumulate in northern my country. When roads are frozen, the friction between wheels and the road surface is greatly weakened, which makes it easy to slip and cause traffic accidents, seriously affecting the road's traffic capacity. At the same time, the road surface shrinks and cracks at low temperatures in low temperature environments, which seriously shortens the service life of the road surface. Therefore, in order to reduce the adverse effects of low temperature and snowfall on the road surface, it is necessary to reduce the formation of snow on the road surface and improve the road surface's resistance to low temperatures.

[0003] Anti-icing composite aggregate is a composite aggregate that can melt snow on the road surface. Its active ingredients are mainly salt compounds. When it is added to the asphalt mixture, under the action of vehicle load, the salt gradually precipitates from the capillary gaps of the mixture, thereby lowering the freezing point of water on the road surface and melting the snow. However, the existing anti-icing composite aggregate can only melt snow for a short time, has poor durability, and does not have the function of adjusting the low-temperature resistance of the road surface, and cannot effectively enhance the low-temperature performance of the asphalt pavement. Summary of the invention

[0004] The present invention provides a phase-change, anti-icing composite aggregate and a preparation method thereof, with the purpose of producing an aggregate having both the functions of temperature regulation and melting ice and snow, so as to solve the problem that the road surface shrinks when exposed to cold in a low-temperature environment, is prone to low-temperature cracking, and has a short service life.

[0005] To achieve its purpose, the present invention adopts the following technical solution: A method for preparing a phase-change, anti-icing composite aggregate comprises the following steps: (1) Preparing salt-storing microcapsules; stirring and dissolving gelatin with deionized water at a mass ratio of 1:20 to 100 to obtain solution A; dissolving sodium chloride with deionized water at a mass ratio of 1:4 to 20 to obtain solution B; using sodium chloride as a core material and gelatin as a wall material, fully mixing solutions A and B at a mass ratio of the core material to the wall material of 2 to 10:1 to obtain solution C, and then spray drying solution C to obtain salt-storing microcapsules; (2) preparing a composite aggregate; first, respectively heating an epoxy resin and polyethylene glycol with a molecular weight of 200 to 1000 to a liquid state, then mixing the liquid epoxy resin, polyethylene glycol and the salt storage microcapsules in step (1) in a mass ratio of 2:1 to 3:1 to 3, then adding an epoxy curing agent and stirring evenly to obtain a mixture, and finally pouring the obtained mixture into a mold for drying and curing, and crushing to obtain a composite aggregate.

[0006] Furthermore, in step (1), a magnetic stirrer is used for stirring, the stirring temperature is 50 to 80° C., the rotation speed is 500 to 800 r / min, and the time is 30 to 50 min.

[0007] Furthermore, in step (1), the spray drying is performed using a spray dryer, the inlet air temperature of the spray dryer is 190 to 210°C, and the inlet air volume is 60 to 90 m 3 / h, the feed rate is 100-180ml / h, the outlet temperature is 90-130℃, and the compressed air pressure is 0.2-0.3Mpa.

[0008] Furthermore, in step (2), heating is performed in an oven at a heating temperature of 60 to 80°C.

[0009] Furthermore, in step (2), the epoxy curing agent is isoprene diamine.

[0010] Furthermore, in step (2), the mass of the epoxy curing agent is 10 to 40% of the mass of the epoxy resin.

[0011] Furthermore, in step (2), the drying is performed in a drying oven, the drying temperature is 60 to 80° C., and the curing time is 2.5 to 4 hours.

[0012] Furthermore, in step (2), the crushing is performed using a crusher.

[0013] Furthermore, in step (2), the particle size of the composite aggregate is 2.36-4.75 mm.

[0014] A phase-change, anti-icing composite aggregate prepared by the preparation method, which takes epoxy resin as a matrix and polyethylene glycol and salt-storage microcapsules as fillers.

[0015] The beneficial effects of the present invention are as follows: The present invention provides a composite aggregate with epoxy resin as a matrix and polyethylene glycol and salt storage microcapsules as fillers. Epoxy resin, as a thermosetting polymer, is widely used in coatings, composite aggregates, building materials and other fields because of its advantages such as high strength, good durability, low curing shrinkage and strong compatibility. Polyethylene glycol with a low molecular weight has a low phase change temperature. When used as a low-temperature phase change material, it can enhance the ice-melting and snow-melting effect of the composite aggregate. Moreover, as the amount of polyethylene glycol increases, the enthalpy value of the composite aggregate also increases, thereby enhancing the ability to regulate the low temperature of the road surface and enhancing the low-temperature crack resistance of the asphalt road surface. Salt-storage microcapsules are used as anti-icing agents for road surfaces. When added to asphalt mixtures, they can effectively prevent or delay road icing. Spray drying is a commonly used microcapsule preparation technology. The principle is to atomize the emulsion containing the core material into fine droplets in a dry hot air flow through an atomizing device. The solvent then evaporates rapidly, and the wall material forms a mesh membrane structure with a sieving effect, thereby obtaining dry powdered microcapsules. Microcapsules with different sustained-release rates can be obtained by adjusting the amount of core material and wall material. The salt-storage microcapsules prepared by spray drying have the advantages of long sustained-release time, long-term ice and snow melting, and can be mass-produced.

[0016] Since epoxy resin forms a three-dimensional network structure after curing, it has high strength and durability and can protect other materials. Therefore, small molecular weight polyethylene glycol and salt storage microcapsules are added to epoxy resin, stirred evenly and cured, and then crushed with a crusher to produce multifunctional composite aggregates with different particle sizes. The main advantages of this composite aggregate are: (1) regulating the road surface temperature to prevent the road surface from shrinking and cracking due to low temperature; (2) the salt storage microcapsules in the composite aggregate can be released to the road surface through load pressure, thereby lowering the freezing point of the road surface; (3) high strength and good durability, while having low-temperature phase change and anti-icing functions, can be added to asphalt mixture to replace part of the aggregate to play a load-bearing role; (4) the raw materials are easy to obtain, the preparation process is simple, and the operability is strong. DETAILED DESCRIPTION

[0017] The present invention will be further described below in conjunction with embodiments: Example 1 A method for preparing a phase-change, anti-icing composite aggregate comprises the following steps: (1) Preparation of salt-storage microcapsules: 5 g of gelatin was dissolved in 100 g of deionized water, and the solution was dissolved for 30 min at 70°C and 700 r / min using a magnetic stirrer to obtain solution A; 20 g of sodium chloride was dissolved in 80 g of deionized water to obtain solution B; sodium chloride was used as the core material and gelatin was used as the wall material, and solutions A and B were fully mixed at a core material to wall material mass ratio of 2:1 to obtain solution C, and solution C was then sent to a spray dryer for spray drying to obtain salt-storage microcapsules; wherein the inlet air temperature of the spray dryer was 210°C and the inlet air volume was 80 m / s.3 / h, feed rate is 150ml / h, outlet temperature is 100℃, compressed air pressure is 0.3Mpa; (2) Preparation of composite aggregates: First, epoxy resin and polyethylene glycol 600 are respectively placed in a beaker, and heated in a 75°C oven for 15 minutes until they are liquid. Then, the liquid epoxy resin, polyethylene glycol and the salt storage microcapsules in step (1) are mixed in a mass ratio of 2:1:1, and then isoprene diamine is added and stirred evenly to obtain a mixture, wherein the mass of isoprene diamine is 10% of the mass of the epoxy resin. Finally, the obtained mixture is poured into a mold and cured in a 70°C drying oven for 3 hours. After curing, the epoxy resin has a certain strength, and the polyethylene glycol phase change material and the salt storage material are coated in the epoxy resin. Finally, the cured mixture is sent to a pulverizer for crushing to obtain a phase change and anti-icing composite aggregate with epoxy resin as the matrix, polyethylene glycol and salt storage microcapsules as fillers, and a particle size of 2.36 mm.

[0018] Example 2 A method for preparing a phase-change, anti-icing composite aggregate comprises the following steps: (1) Preparation of salt-storage microcapsules: 5 g of gelatin was dissolved in 120 g of deionized water, and the solution was dissolved for 33 min at 65°C and 720 r / min using a magnetic stirrer to obtain solution A; 20 g of sodium chloride was dissolved in 100 g of deionized water to obtain solution B; sodium chloride was used as the core material and gelatin was used as the wall material, and solutions A and B were fully mixed at a core material to wall material mass ratio of 4:1 to obtain solution C, and solution C was then sent to a spray dryer for spray drying to obtain salt-storage microcapsules; wherein the inlet air temperature of the spray dryer was 190°C and the inlet air volume was 60 m 3 / h, feed rate is 120ml / h, outlet temperature is 90℃, compressed air pressure is 0.2Mpa; (2) Preparation of composite aggregates: First, epoxy resin and polyethylene glycol 600 are respectively placed in a beaker, and heated in a 60°C oven for 15 minutes until they are liquid. Then, the liquid epoxy resin, polyethylene glycol and the salt storage microcapsules in step (1) are mixed in a mass ratio of 2:2:1, and then isoprene diamine is added and stirred evenly to obtain a mixture, wherein the mass of isoprene diamine is 20% of the mass of the epoxy resin. Finally, the obtained mixture is poured into a mold and cured in a 60°C drying oven for 2.5 hours. After curing, the epoxy resin has a certain strength, and the polyethylene glycol phase change material and the salt storage material are coated in the epoxy resin. Finally, the cured mixture is sent to a pulverizer for crushing to obtain a phase change and anti-icing composite aggregate with epoxy resin as the matrix, polyethylene glycol and salt storage microcapsules as fillers, and a particle size of 3.55 mm.

[0019] Example 3 A method for preparing a phase-change, anti-icing composite aggregate comprises the following steps: (1) Preparation of salt-storage microcapsules: 5 g of gelatin was dissolved in 150 g of deionized water, and the solution was dissolved for 35 min at 50°C and 500 r / min using a magnetic stirrer to obtain solution A; 20 g of sodium chloride was dissolved in 140 g of deionized water to obtain solution B; sodium chloride was used as the core material and gelatin was used as the wall material, and solutions A and B were fully mixed at a core material to wall material mass ratio of 5:1 to obtain solution C, and solution C was then sent to a spray dryer for spray drying to obtain salt-storage microcapsules; wherein the inlet air temperature of the spray dryer was 200°C and the inlet air volume was 75 m 3 / h, feed rate is 100ml / h, outlet temperature is 110℃, compressed air pressure is 0.2Mpa; (2) Preparation of composite aggregates: First, epoxy resin and polyethylene glycol 600 are respectively placed in a beaker, and heated in an oven at 80°C for 15 minutes until liquid, and then the liquid epoxy resin, polyethylene glycol and the salt storage microcapsules in step (1) are mixed in a mass ratio of 2:3:1, and then isoprene diamine is added and stirred evenly to obtain a mixture, wherein the mass of isoprene diamine is 40% of the mass of the epoxy resin; finally, the obtained mixture is poured into a mold and cured in an oven at 80°C for 4 hours. After curing, the epoxy resin has a certain strength, and the polyethylene glycol phase change material and the salt storage material are coated in the epoxy resin. Finally, the cured mixture is sent to a pulverizer for crushing to obtain a phase change and anti-icing composite aggregate with epoxy resin as the matrix, polyethylene glycol and salt storage microcapsules as fillers, and a particle size of 4.75 mm.

[0020] Example 4 A method for preparing a phase-change, anti-icing composite aggregate comprises the following steps: (1) Preparation of salt-storage microcapsules: 5 g of gelatin was dissolved in 180 g of deionized water, and the solution was dissolved for 40 min at 75°C and 650 r / min using a magnetic stirrer to obtain solution A; 20 g of sodium chloride was dissolved in 150 g of deionized water to obtain solution B; sodium chloride was used as the core material and gelatin was used as the wall material, and solutions A and B were fully mixed at a core material to wall material mass ratio of 6:1 to obtain solution C, and solution C was then sent to a spray dryer for spray drying to obtain salt-storage microcapsules; wherein the inlet air temperature of the spray dryer was 200°C and the inlet air volume was 80 m 3 / h, feed rate is 130ml / h, outlet temperature is 130℃, compressed air pressure is 0.3Mpa; (2) Preparation of composite aggregates: First, epoxy resin and polyethylene glycol 600 are respectively placed in a beaker, and heated in a 75°C oven for 15 minutes until they are liquid. Then, the liquid epoxy resin, polyethylene glycol and the salt storage microcapsules in step (1) are mixed in a mass ratio of 2:1:2, and then isoprene diamine is added and stirred evenly to obtain a mixture, wherein the mass of isoprene diamine is 25% of the mass of the epoxy resin. Finally, the obtained mixture is poured into a mold and cured in an 80°C drying oven for 4 hours. After curing, the epoxy resin has a certain strength, and the polyethylene glycol phase change material and the salt storage material are coated in the epoxy resin. Finally, the cured mixture is sent to a pulverizer for pulverization to obtain a phase change and anti-icing composite aggregate with epoxy resin as the matrix, polyethylene glycol and salt storage microcapsules as fillers, and a particle size of 4.75 mm.

[0021] Example 5 A method for preparing a phase-change, anti-icing composite aggregate comprises the following steps: (1) Preparation of salt-storage microcapsules: 5 g of gelatin was dissolved in 200 g of deionized water, and the solution was dissolved for 50 min at 50°C and 800 r / min using a magnetic stirrer to obtain solution A; 20 g of sodium chloride was dissolved in 160 g of deionized water to obtain solution B; sodium chloride was used as the core material and gelatin was used as the wall material, and solutions A and B were fully mixed at a core material to wall material mass ratio of 10:1 to obtain solution C, and solution C was then sent to a spray dryer for spray drying to obtain salt-storage microcapsules; wherein the inlet air temperature of the spray dryer was 190°C and the inlet air volume was 90 m / s. 3 / h, feed rate is 100ml / h, outlet temperature is 90℃, compressed air pressure is 0.3Mpa; (2) Preparation of composite aggregates: First, epoxy resin and polyethylene glycol 1000 are respectively placed in a beaker, and heated in a 60°C oven for 15 minutes until liquid, and then the liquid epoxy resin, polyethylene glycol and the salt storage microcapsules in step (1) are mixed in a mass ratio of 1:1:1, and then isoprene diamine is added and stirred evenly to obtain a mixture, wherein the mass of isoprene diamine is 30% of the mass of the epoxy resin; finally, the obtained mixture is poured into a mold and cured in a 60°C drying oven for 3 hours. After curing, the epoxy resin has a certain strength, and the polyethylene glycol phase change material and the salt storage material are coated in the epoxy resin. Finally, the cured mixture is sent to a pulverizer for pulverization to obtain a phase change and anti-icing composite aggregate with epoxy resin as the matrix, polyethylene glycol and salt storage microcapsules as fillers, and a particle size of 4.32 mm.

[0022] Example 6 A method for preparing a phase-change, anti-icing composite aggregate comprises the following steps: (1) Preparation of salt-storage microcapsules: 5 g of gelatin was dissolved in 300 g of deionized water, and the solution was dissolved for 30 min at 80°C and 500 r / min using a magnetic stirrer to obtain solution A; 20 g of sodium chloride was dissolved in 200 g of deionized water to obtain solution B; sodium chloride was used as the core material and gelatin was used as the wall material, and solutions A and B were fully mixed at a core material to wall material mass ratio of 8:1 to obtain solution C, and solution C was then sent to a spray dryer for spray drying to obtain salt-storage microcapsules; wherein the inlet air temperature of the spray dryer was 210°C and the inlet air volume was 80 m 3 / h, feed rate is 150ml / h, outlet temperature is 100℃, compressed air pressure is 0.3Mpa; (2) Preparation of composite aggregates: First, epoxy resin and polyethylene glycol 600 are respectively placed in a beaker, and heated in a 75°C oven for 15 minutes until they are liquid. Then, the liquid epoxy resin, polyethylene glycol and the salt storage microcapsules in step (1) are mixed in a mass ratio of 2:3:2, and then isoprene diamine is added and stirred evenly to obtain a mixture, wherein the mass of isoprene diamine is 30% of the mass of the epoxy resin. Finally, the obtained mixture is poured into a mold and cured in a 70°C drying oven for 3 hours. After curing, the epoxy resin has a certain strength, and the polyethylene glycol phase change material and the salt storage material are coated in the epoxy resin. Finally, the cured mixture is sent to a pulverizer for crushing to obtain a phase change and anti-icing composite aggregate with epoxy resin as the matrix, polyethylene glycol and salt storage microcapsules as fillers, and a particle size of 3.68 mm.

[0023] As needed, the composite aggregate particles prepared in Examples 1-6 are added to the asphalt mixture instead of part of the mineral material, so that it has both the functions of temperature regulation and melting ice and snow, so as to solve the problem of low-temperature cracking caused by cold shrinkage of the road surface in a low-temperature environment, and effectively enhance the low-temperature performance of the asphalt pavement.

[0024] The crushing value, torsional force and phase change enthalpy of the composite aggregates obtained in Examples 1-6 were tested respectively to characterize the compressive strength, ice and snow melting ability and temperature regulation ability of the composite aggregates during use. The test method is as follows: (1) Crushing value test: The crushing value of composite aggregate was tested according to the crushing value test method of the “Highway Engineering Aggregate Test Code”. The test results are shown in Table 1.

[0025] (2) Torsion test: The composite aggregate was mixed into the asphalt mixture instead of the 2.36-4.75 mm ordinary aggregate to prepare the Marshall specimen. A circle of equal diameter was drawn on the surface of the Marshall specimen with a white oil pen, and the same mass of distilled water was weighed with a dropper and evenly spread inside the circle. Then 4 molds were evenly placed and placed in a constant temperature box at -10°C, and the surface of the specimen was kept level. After 90 minutes, the specimen was taken out and the mold was quickly twisted off with a torque wrench. The torque value was recorded. The test results are shown in Table 1. The control group used ordinary aggregate to make the same Marshall specimen, and its torque value was 0.814 N*m. The smaller the torque value compared with the control group, the stronger the anti-icing ability of the multifunctional aggregate.

[0026] (3) Phase change enthalpy test: Differential scanning calorimetry (DSC) was used to test the phase change temperature and phase change enthalpy of the composite aggregate. The test results are shown in Table 1.

[0027] Table 1 Composite aggregate performance test It can be seen from Table 1 that the crushing values ​​of the composite aggregates obtained in Examples 1-6 are all less than the requirements of the "Highway Engineering Aggregate Test Code" standard that the crushing value of coarse aggregate for cement concrete should be less than 26%, and the crushing value of coarse aggregate for asphalt concrete should be less than 30%, indicating that the mechanical properties of the multifunctional aggregate meet the use conditions, and the higher the proportion of epoxy resin, the higher the strength of the composite aggregate.

[0028] Compared with the torsional torque of 0.814 N*m in the torsional test of the control group, the torsional torque of the composite aggregates in Examples 1-6 decreased, and the greater the proportion of polyethylene glycol and salt storage materials, the better the ice-melting and snow-melting effect.

[0029] Through DSC testing, it can be seen that the composite aggregate has a certain enthalpy value, and its enthalpy value increases with the increase of the proportion of polyethylene glycol. It can play a role in regulating the low temperature of the road surface and enhance the low-temperature crack resistance of the asphalt pavement.

Claims

1. A method for preparing a phase-change, anti-icing composite aggregate, characterized in that: The following steps are involved: (1) Preparing salt-storing microcapsules; stirring and dissolving gelatin with deionized water at a mass ratio of 1:20 to 100 to obtain solution A; dissolving sodium chloride with deionized water at a mass ratio of 1:4 to 20 to obtain solution B; using sodium chloride as a core material and gelatin as a wall material, fully mixing solutions A and B at a mass ratio of the core material to the wall material of 2 to 10:1 to obtain solution C, and then spray drying solution C to obtain salt-storing microcapsules; (2) preparing a composite aggregate; first, respectively heating an epoxy resin and polyethylene glycol with a molecular weight of 200 to 1000 to a liquid state, then mixing the liquid epoxy resin, polyethylene glycol and the salt storage microcapsules in step (1) in a mass ratio of 2:1 to 3:1 to 3, then adding an epoxy curing agent and stirring evenly to obtain a mixture, and finally pouring the obtained mixture into a mold for drying and curing, and crushing to obtain a composite aggregate.

2. The method for preparing a phase-change, anti-icing composite aggregate according to claim 1, characterized in that: In step (1), a magnetic stirrer is used for stirring, the stirring temperature is 50-80° C., the rotation speed is 500-800 r / min, and the time is 30-50 min.

3. The method for preparing a phase-change, anti-icing composite aggregate according to claim 2, characterized in that: In step (1), spray drying is performed using a spray dryer, the inlet air temperature of the spray dryer is 190-210°C, and the inlet air volume is 60-90m 3 / h, the feed rate is 100-180ml / h, the outlet temperature is 90-130℃, and the compressed air pressure is 0.2-0.3Mpa.

4. The method for preparing a phase-change, anti-icing composite aggregate according to claim 3, characterized in that: In step (2), heating is performed in an oven at a temperature of 60 to 80°C.

5. The method for preparing a phase-change, anti-icing composite aggregate according to claim 4, characterized in that: In step (2), the epoxy curing agent is isoprene diamine.

6. The method for preparing a phase-change, anti-icing composite aggregate according to claim 5, characterized in that: The mass of the epoxy curing agent in step (2) is 10 to 40% of the mass of the epoxy resin.

7. The method for preparing a phase-change, anti-icing composite aggregate according to claim 6, characterized in that: In step (2), drying is performed in a drying oven at a drying temperature of 60 to 80° C. and a curing time of 2.5 to 4 hours.

8. The method for preparing a phase-change, anti-icing composite aggregate according to claim 7, characterized in that: In step (2), the crushing is performed using a crusher.

9. The method for preparing a phase-change, anti-icing composite aggregate according to claim 8, characterized in that: The particle size of the composite aggregate in step (2) is 2.36 to 4.75 mm.

10. A phase-change, anti-icing composite aggregate prepared by the preparation method according to any one of claims 1 to 9, which has epoxy resin as a matrix and polyethylene glycol and salt-storage microcapsules as fillers.

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