阅读说明：本技术 一种沥青混合料的高模量改性剂共混物 (High modulus modifier blend for asphalt mixture ) 是由 周成冈 韩波 吴金平 于 2020-06-29 设计创作，主要内容包括：本发明涉及一种沥青混合料改性用有机-无机复合材料,具体为一种沥青混合料的高模量改性剂共混物,所述所述高模量改性剂共混物由改性硫酸钙晶须和聚烯烃组成,且所述改性硫酸钙晶和所述聚烯烃的质量比为20～80:20～80。本发明所述的高模量改性剂共混物用于沥青混合料中,可显著提高沥青混合料的抗车辙性能,也能提高沥青混合料的水稳定性及低温抗裂性能,且还具有原料易得和价格低廉等优点。(The invention relates to an organic-inorganic composite material for modifying an asphalt mixture, in particular to a high-modulus modifier blend of the asphalt mixture, wherein the high-modulus modifier blend consists of modified calcium sulfate whiskers and polyolefin, and the mass ratio of the modified calcium sulfate crystals to the polyolefin is 20-80: 20-80. The high-modulus modifier blend is used in the asphalt mixture, can obviously improve the anti-rutting performance of the asphalt mixture, can also improve the water stability and the low-temperature crack resistance of the asphalt mixture, and has the advantages of easily available raw materials, low price and the like.)

1. The high-modulus modifier blend of the asphalt mixture is characterized by comprising modified calcium sulfate whiskers and polyolefin, wherein the mass ratio of the modified calcium sulfate crystals to the polyolefin is 20-80: 20-80.

2. The high modulus modifier blend for asphalt mixtures according to claim 1, wherein the modified calcium sulfate whiskers are obtained by modifying calcium sulfate whiskers with a modifier.

3. The high modulus modifier blend for asphalt mixtures of claim 2, wherein said modifier is an organic acid, an organic acid salt or a coupling agent.

4. The high modulus modifier blend for asphalt mixtures of claim 2, wherein said calcium sulfate whiskers are calcium sulfate dihydrate whiskers, calcium sulfate hemihydrate whiskers, or calcium sulfate anhydrite whiskers.

5. The high modulus modifier blend for asphalt mixture of claim 1, wherein said polyolefin is one or more of polypropylene, polyethylene, ethylene-vinyl acetate copolymer, polyethylene wax and ethylene-propylene-diene monomer rubber.

6. The high modulus modifier blend for asphalt mixtures according to claim 5, wherein said polypropylene: the polyethylene: the ethylene-vinyl acetate copolymer: the polyethylene wax: and the ethylene propylene diene monomer is 55-70: 0 to 20: 0 to 20: 0 to 15:0 to 15.

7. The high modulus modifier blend for asphalt mixtures of claim 6, wherein said polypropylene is random copolymer polypropylene, block copolymer polypropylene or homopolypropylene.

8. The high modulus modifier blend for asphalt mixture as claimed in claim 6, wherein the melt index of polypropylene is 3-40 g/10min, the melt index of polyethylene is 1-40 g/10min, and the melt index of ethylene-vinyl acetate copolymer is 1-40 g/10 min.

9. A process for the preparation of a high modulus modifier blend for asphalt mixtures according to any one of claims 1 to 8, characterized by the following steps: uniformly mixing the components of the raw materials at normal temperature and normal pressure, adding the mixture into a double-screw extruder, performing melt extrusion under the conditions of the barrel temperature of 150-210 ℃, the main machine rotation speed of 250-300 rpm and the feeding speed of 350-400 kgph, and then performing granulation and drying to obtain the high-modulus modifier blend.

Technical Field

The invention relates to an organic-inorganic composite material for modifying an asphalt mixture, in particular to a high-modulus modifier blend for the asphalt mixture.

Background

With the continuous and continuous high-speed construction of asphalt roads, in order to overcome the problems of common rutting diseases and serious damage of the road surface of common asphalt roads, people add high modulus agents into road asphalt or asphalt mixtures to improve the performance of the asphalt roads, wherein organic polymer modified asphalt mixtures such as SBS and the like are most applied to high-grade asphalt roads due to good rutting resistance. However, the SBS and other modified materials are high in price, so that the construction cost of the asphalt road is increased.

Disclosure of Invention

The invention provides a high modulus agent modifier blend of asphalt mixture, which is low in price and can enable the pavement performance of the asphalt mixture to be comparable to or better than SBS in view of the problem of high price of modified materials such as SBS.

A high modulus modifier blend for asphalt mixes consisting of modified calcium sulfate crystals and a polyolefin.

The invention has the beneficial effects that: the high modulus modifier blend utilizes the synergistic effect of calcium sulfate whiskers and polyolefin to improve the pavement performance of the asphalt mixture.

Further, the mass ratio of the modified calcium sulfate whiskers to the polyolefin is 20-80: 20-80.

The invention has the beneficial effects that: the high content of the calcium sulfate whiskers is beneficial to improving the anti-rutting performance of the calcium sulfate whiskers and reducing the price of the high modulus modifier.

Further, the modified calcium sulfate whisker is prepared by modifying calcium sulfate whisker with a modifier.

The invention has the beneficial effects that: the calcium sulfate crystal whisker has wide source and easily obtained raw materials.

Further, the modifier is organic acid, organic acid salt or coupling agent.

The invention has the beneficial effects that: the modified calcium sulfate whisker is beneficial to improving the anti-rutting high-temperature performance of the asphalt mixture, is also beneficial to the anti-frost cracking performance and the water stability performance, and can obviously reduce the price of the modifier due to the low price of the calcium sulfate whisker.

Further, the calcium sulfate whisker is calcium sulfate dihydrate whisker, calcium sulfate hemihydrate whisker or calcium sulfate anhydrite whisker.

Further, the polyolefin is one or a mixture of more of polypropylene, polyethylene, ethylene-vinyl acetate copolymer, polyethylene wax and ethylene propylene diene monomer.

The invention has the beneficial effects that: wherein, the polypropylene is taken as the main material, and the polyethylene, the ethylene-vinyl acetate copolymer, the polyethylene wax and the ethylene propylene diene monomer are taken as the auxiliary materials, which is favorable for the high temperature resistance and the low temperature resistance of the asphalt mixture. The copolymerization of the polyethylene and the ethylene-vinyl acetate is favorable for improving the low-temperature performance of the asphalt mixture, and the polyethylene wax is favorable for the granulation processability of the high-content calcium sulfate whisker blend.

Further, the polypropylene in the mixture is: the polyethylene: the ethylene-vinyl acetate copolymer: the polyethylene wax: and the ethylene propylene diene monomer is 55-70: 0 to 20: 0 to 20: 0 to 15:0 to 15.

Further, the polypropylene is random copolymer polypropylene, block copolymer polypropylene or homopolymerized polypropylene.

The invention has the beneficial effects that: the polypropylene is beneficial to improving the high-temperature performance of the asphalt mixture.

Further, the melt index of the polypropylene is 3-40 g/10min, the melt index of the polyethylene is 1-40 g/10min, and the melt index of the ethylene-vinyl acetate copolymer is 1-40 g/10 min.

A method of preparing a high modulus modifier blend for asphalt mixes comprising the steps of: uniformly mixing the components of the raw materials at normal temperature and normal pressure, adding the mixture into a double-screw extruder, performing melt extrusion at the barrel temperature of 150-210 ℃, the main machine rotation speed of 250-300 rpm and the feeding speed of 350-400 kgph, and performing granulation and drying to obtain the high-modulus modifier blend.

The invention has the beneficial effects that: the high-modulus modifier blend disclosed by the invention adopts high-content calcium sulfate whiskers, the application field of the calcium sulfate whiskers is expanded, and the price of the high-modulus modifier of the asphalt mixture is also obviously reduced; in addition, the high-temperature anti-rutting performance and the fatigue resistance of the asphalt mixture can be obviously improved, and the water stability and the low-temperature stability of the asphalt mixture can be improved simultaneously. And because the price of the high-modulus modifier blend has obvious advantage over SBS, the high-modulus modifier blend can be used for asphalt highways with different grade requirements of high, medium and low by adjusting the addition amount of the modifier mixture in the asphalt mixture.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, embodiments of the present invention are further described below.

Here, it should be noted that the organic acid, organic salt and coupling agent in the chemical agent are not limited in the present invention, and the organic acid, organic salt and coupling agent in the chemical agent can be exemplified as the organic acid, organic salt and coupling agent in the present invention, for example, the organic acid can be formic acid, acetic acid, propionic acid, butyric acid, caprylic acid, adipic acid, oxalic acid, malonic acid, succinic acid, stearic acid, etc., the organic salt can be sodium acetate, sodium benzoate, sodium ethoxide, etc., the coupling agent can be silanes (aminopropyltriethoxysilane (KH550), glycidoxypropyltrimethoxysilane (KH560), methacryloxypropyltrimethoxysilane (KH570), vinyltriethoxysilane (A151), vinyltriethoxysilane (A171), mercaptopropyltrimethoxysilane (ethyl) oxysilane (KH580, KH590), ethylenediamine propyltriethoxysilane (KH792), or ethylenediamine propyl methyldimethoxysilane) or titanates (aluminates, zirconates, borates).

The modified calcium sulfate whisker is obtained by modifying the calcium sulfate whisker with a modifier, and the specific steps of the modification treatment are as follows:

adding calcium sulfate whiskers and a modifier into absolute ethyl alcohol to obtain a modified mixture, wherein the mass ratio of the calcium sulfate whiskers to the modifier in the modified mixture is 100: and 2, the solid-to-liquid ratio of the calcium sulfate whiskers to the absolute ethyl alcohol is 1:4, the modified mixture is sequentially stirred and filtered to obtain a filtrate, the filtrate is dried to obtain the modified calcium sulfate whiskers, and the drying temperature is 70-80 ℃.

The polyethylene in the present invention may be high density polyethylene or low density polyethylene, or polyethylene regrind.

< example 1>

In this embodiment, the modified calcium sulfate whisker is obtained by modifying calcium sulfate with aminopropyltriethoxysilane (KH 550).

The polyolefin is a mixture of random copolymerization polypropylene, high density polyethylene, ethylene-vinyl acetate copolymer, polyethylene wax and ethylene propylene diene monomer, and the mass ratio of the raw materials in the mixture is as follows: the random copolymer polypropylene comprises polyethylene, ethylene-vinyl acetate copolymer, polyethylene wax and ethylene propylene diene monomer rubber, wherein the ratio of the polyethylene to the ethylene-vinyl acetate copolymer to the ethylene propylene diene monomer rubber is 60:10:10:10: 10. The melt index of the block copolymerization polypropylene is 20g/10min, the melt index of the polyethylene is 15g/10min, and the melt index of the ethylene-vinyl acetate copolymer is 25g/10 min.

Uniformly mixing the obtained modified calcium sulfate whisker and polyolefin according to the mass ratio of 25:75 at normal temperature and normal pressure, adding the mixture into a double-screw extruder, carrying out melt extrusion under the conditions that the temperature of a cylinder body is 150 ℃, the rotating speed of a main engine is 250-300 rpm and the feeding speed is 350-400 kgph (kg per hour), and carrying out granulation and drying to obtain the high-modulus modifier blend.

< example 2>

In this embodiment, the modified calcium sulfate whisker is obtained by modifying calcium sulfate dihydrate whisker with stearic acid.

The polyolefin is a mixture of block copolymerization polypropylene, low density polyethylene, ethylene-vinyl acetate copolymer, polyethylene wax and ethylene propylene diene monomer, and the mass ratio of the raw materials in the mixture is as follows: the random copolymer polypropylene comprises polyethylene, ethylene-vinyl acetate copolymer, polyethylene wax and ethylene propylene diene monomer rubber, wherein the ratio of polyethylene to ethylene-vinyl acetate copolymer to polyethylene wax to ethylene propylene diene monomer rubber is 55:15:5:10: 15. The melt index of the block copolymerization polypropylene is 10g/10min, the melt index of the polyethylene is 5g/10min, and the melt index of the ethylene-vinyl acetate copolymer is 7g/10 min.

Uniformly mixing the obtained modified calcium sulfate whisker and polyolefin according to the mass ratio of 35:65 at normal temperature and normal pressure, adding the mixture into a double-screw extruder, performing melt extrusion under the conditions that the temperature of a cylinder body is 170 ℃, the rotating speed of a main engine is 250-300 rpm and the feeding speed is 350-400 kgph, and performing granulation and drying to obtain the high-modulus modifier blend.

< example 3>

In this embodiment, the modified calcium sulfate whisker is obtained by modifying calcium sulfate hemihydrate whisker with sodium acetate.

The polyolefin is a mixture of homopolymerized polypropylene, high-density polyethylene, ethylene-vinyl acetate copolymer, polyethylene wax and ethylene propylene diene monomer, and the mass ratio of the raw materials in the mixture is as follows: the random copolymer polypropylene comprises polyethylene, ethylene-vinyl acetate copolymer, polyethylene wax and ethylene propylene diene monomer rubber, wherein the ratio of polyethylene to ethylene-vinyl acetate copolymer to polyethylene wax to ethylene propylene diene monomer rubber is 70:5:5:10: 10. The melt index of the block copolymerization polypropylene is 30g/10min, the melt index of the polyethylene is 35g/10min, and the melt index of the ethylene-vinyl acetate copolymer is 35g/10min, which is not limited in this embodiment.

Uniformly mixing the obtained modified calcium sulfate whisker and polyolefin according to the mass ratio of 35:65 at normal temperature and normal pressure, adding the mixture into a double-screw extruder, performing melt extrusion under the conditions of the barrel temperature of 210 ℃, the main machine rotating speed of 250-300 rpm and the feeding speed of 350-400 kgph, and performing granulation and drying to obtain the high-modulus modifier blend.

< comparative example 1>

In this embodiment, the polyolefin is a mixture of homo-polypropylene, high-density polyethylene, ethylene-vinyl acetate copolymer, polyethylene wax, and ethylene-propylene-diene monomer, and the mass ratio of each raw material in the mixture is: the random copolymer polypropylene comprises polyethylene, ethylene-vinyl acetate copolymer, polyethylene wax and ethylene propylene diene monomer rubber, wherein the ratio of polyethylene to ethylene-vinyl acetate copolymer to polyethylene wax to ethylene propylene diene monomer rubber is 70:5:5:10: 10. The melt index of the block copolymerization polypropylene is 40g/10min, the melt index of the polyethylene is 35g/10min, and the melt index of the ethylene-vinyl acetate copolymer is 40g/10min, which is not limited in this embodiment.

And adding the obtained polyolefin into a double-screw extruder, performing melt extrusion under the conditions that the barrel temperature is 150 ℃, the main machine rotating speed is 250-300 rpm and the feeding speed is 350-400 kgph, and performing granulation and drying to obtain the high-modulus modifier blend.

< comparative example 2>

In this embodiment, the modified calcium sulfate whisker is obtained by modifying calcium sulfate with aminopropyltriethoxysilane (KH 550).

And adding the obtained modified calcium sulfate whisker into a double-screw extruder, performing melt extrusion at the barrel temperature of 150 ℃, the main machine rotating speed of 250-300 rpm and the feeding speed of 350-400 kgph, and performing granulation and drying to obtain the high-modulus modifier blend.

Respectively carrying out performance tests on the high modulus modifier blends obtained in examples 1-3 and comparative examples 1-2, adopting AC-20C as stone and No. 70 as asphalt, mixing the AC-20C with the asphalt to obtain an asphalt mixture, wherein the asphalt-stone ratio of the asphalt to the stone in the asphalt mixture is 1: 4.3, mixing the high modulus modifier blends obtained in examples 1-3 and comparative examples 1-2 with the asphalt mixture to obtain a mixture of the asphalt mixture and the high modulus modifier blend, wherein the mass of the high modulus modifier blend in the mixture is 2-7% of the mass of asphalt in the asphalt mixture, and the types of the mixture of the asphalt mixture and the high modulus modifier blend in each test example are shown in table 1.

TABLE 1 types of mixtures

The performance test of the mixture of the asphalt mixture and the high modulus modifier blend of each test example shown in table 1 is carried out according to the following industry standards:

1. road engineering asphalt and asphalt mixture test protocol (JTG E20-2011)

2. Highway asphalt pavement construction technical Specification (JTG F40-2004)

The specific laboratory preparation process comprises the following steps: the high modulus modifier blend and the stone material are simultaneously added into a preheating 190 ℃ stirring pot for stirring for 30 seconds, then the asphalt with the temperature of 155 ℃ and 165 ℃ is added for stirring for 90 seconds, and finally the mineral powder is added for stirring for 90 seconds.

The mixtures in table 1 (the amount of the mixture in each test example is the same) are subjected to marshall performance, water stability and high and low temperature performance tests, and detection indexes comprise soaking residual stability, freeze-thaw splitting strength ratio, dynamic stability and maximum low-temperature bending strain. The results of the performance tests of each mixture are shown in table 2.

TABLE 2 example Properties of mixtures of various asphalt mixes with high modulus modifier blends

It can be seen from table 2 that, after the high modulus modifier blend of the present invention is added to the asphalt mixture, the high temperature stability of the asphalt mixture is significantly improved compared to the ordinary asphalt, and the water stability and the low temperature crack resistance are also improved compared to the ordinary asphalt mixture, but the maximum low temperature bending strain is slightly reduced when the calcium sulfate whiskers in the high modulus modifier blend are up to 60%.

Furthermore, it can be seen from Table 2 that all the examples showed a dynamic stability of more than 4000 cycles/mm, more than 5000 cycles/mm and even more than 6000 cycles/mm. Therefore, the modification effect of the high-modulus modifier blend is mainly determined by the content of the modified calcium sulfate whiskers added in the blend within a certain range, and the higher the content of the whiskers is, the stronger the anti-rutting performance improvement capability of the blend on the asphalt mixture is, but the lower the anti-rutting performance of the blend is after the anti-rutting performance reaches the extreme value. As shown in examples 3-1 and 3-2, the content of the modified calcium sulfate whiskers in the high modulus modifier blend is high to a certain extent, and the reduction of the mixing amount in the asphalt mixture is beneficial to the improvement of the performance, so that the high content of the gypsum whisker modifier has higher cost performance. In addition, as can be seen from the blank comparative example 01 and the blank comparative example 02, the pure polyolefin blend and the pure modified calcium sulfate whisker have opposite effects on the water stability and the low-temperature stability of the asphalt mixture, the former has a reducing effect, and the latter has an improving effect, but the opposite effects are achieved on the low-temperature crack resistance. However, the two have a certain improvement effect on the rutting resistance of the asphalt mixture, but the two are not obvious. And the anti-rutting performance of the two materials is obviously improved after the two materials are blended, which means that the two materials have synergistic improvement effect on the anti-rutting performance in the blend. It can also be seen from the comparative example (ordinary SBS modified asphalt mixture) in Table 2 that the road performance of the mixture doped with the high modulus modifier blend of the invention is not inferior or even better than that of the SBS modified ordinary asphalt mixture with the same doping amount except the low temperature crack resistance. The mixing process of the asphalt mixture is basically unchanged, the equipment and the process operation process of SBS modified asphalt are omitted, and the price is much lower than that of SBS materials. Therefore, in the region where the requirement on low-temperature crack resistance is not particularly high, the high-modulus modifier blend can replace SBS materials, and the construction cost of the asphalt road is obviously reduced.

In this document, the terms front, back, up, down, and the like are used for the sake of clarity and convenience in describing the technical solutions. It is to be understood that the use of the directional terms should not be taken to limit the scope of the claims.

The features of the embodiments and embodiments described herein above may be combined with each other without conflict.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.