Discussion on the production technology of modified asphalt

The rapid development of China's national economy has brought about the rapid growth of road traffic, the large scale of the vehicle and the heavy road transport. Although many highway asphalt pavement used to meet the requirements of heavy traffic road asphalt or imported asphalt, still can not meet the needs of asphalt pavement rutting, cracking, brittle pits and other diseases are very serious. On the pitch, influencing factors of asphalt pavement performance of the asphalt dosage, contact surface of asphalt film thickness, asphalt layer thickness, asphalt and asphalt flow over the characteristics of oil source and asphalt grade, temperature sensitivity, sense, chemical group, aging asphalt asphalt and asphalt and stone points the adhesion and viscosity. In order to improve the performance of asphalt and asphalt mixture, the modified asphalt is one of the effective measures to improve the performance of asphalt mixture. In this paper, from the SBS modified asphalt modification principle, the production process of the related issues are briefly described.

1 modified asphalt phase solubility mechanism

The modified asphalt is used as a dispersed phase, and the system is composed of a physical method with a certain particle size to be uniformly dispersed in a continuous phase. There is part of the polymer adsorption, easy segregation occurred between the two phases. The phase solubility is the polymer which is dispersed phase as the polymer with a certain particle size, evenly distributed in the asphalt phase, and the modification effect is remarkable. Therefore, the production of SBS modified asphalt is the problem of the phase solubility of asphalt and SBS. If the compatibility is not good, it will happen asphalt segregation, the technical indexes of modified asphalt have great influence.

2 production of modified asphalt raw materials

The raw materials for producing modified asphalt include matrix asphalt, SBS modifier and stabilizer.

2.1 selection of matrix asphalt

SBS modified asphalt is a small amount of thermoplastic rubber mixed in the matrix asphalt, through a certain process, the nature of the modified asphalt and the asphalt is closely related to the matrix. So it is the key to produce the modified asphalt which meets the requirements of the specification.

Compatibility of 2.1.1 matrix asphalt and modifier SBS

The difference of composition and properties of petroleum asphalt, in the final analysis, is composed of crude oil and its property. The study shows that the mixture of asphalt is a complex mixture, and the elastic model is presented in the ambient temperature. High quality asphalt due to saturated hydrocarbon, aromatic hydrocarbon, which contains the suitable resin and asphaltene proportion, adding modifier due to sufficient soft phase asphalt, asphalt mixture aromatic dissolved, forming uniform structure / system. However, the three major indexes of the mechanism can not completely reflect the component properties of the asphalt. Therefore, we used the test in the production of high-speed shearing machine, the mechanism of asphalt sampling and modification of different varieties of modified agent, and ultimately selected the appropriate formula and technology.

2.1.2 selection of the appropriate mechanism of asphalt labeling

Modified asphalt penetration level is by 25 DEG C to distinguish. In general, the modified process usually by means of matrix asphalt penetration will decrease 20-25. As No. 70 heavy traffic asphalt modified penetration in general about 45-50, can only meet the requirement of I-D. Therefore, the processing of I-D grade general selection of 70 asphalt, I-C grade general selection of 90 asphalt, B I- grade general selection of asphalt 110.

2.1.3 matrix asphalt to meet the requirements of the technical standards for heavy asphalt

The current road use asphalt has ordinary road asphalt and heavy traffic asphalt. Through the comparison of the performance of the two, it is found that the heavy asphalt has stressed the requirement of 15 degree and the wax content. The outstanding advantage of SBS modified asphalt is that the low temperature extension performance is greatly improved, so the low temperature ductility of the base asphalt is also higher. At the same time, the amount of wax content in the matrix asphalt is also directly related to the thermal performance of the modified asphalt. When the high wax content is high, the phase solubility of matrix asphalt and SBS is poor, the modification effect is not ideal, and the temperature performance index PI value is also smaller. Therefore in the "highway modified asphalt pavement construction technical specification" (JTJ036-98) in the clear provisions of the processing of modified asphalt matrix asphalt must meet the requirements of heavy asphalt.

2.2 SBS modifier

SBS modifier has two properties, such as rubber and plastic, with rubber elasticity at room temperature, and can melt and flow into a plastic material under high temperature. The application effect of SBS modifier in the production of modified asphalt is the most ideal:

1) change the rheological properties of asphalt, visco elasticity and ductility increase, the impact resistance of the road surface, anti cracking capacity, wear resistance capacity are greatly increased, can extend the service life of asphalt pavement;

2) increase the adhesion and adhesion of asphalt, improve the adhesion of asphalt and sand stone, improve the strength of asphalt mixture and waterproof ability, and enhance the durability of asphalt pavement;

3) reduced the temperature sensitivity of asphalt, the asphalt penetration and softening point decline, expand the scope of plastic deformation, flow resistance ability is improved, the flat asphalt pavement performance and anti rutting performance is improved, the increase of train speed, reduce road maintenance.

According to the different proportion of styrene and butadiene and the difference of the molecular structure, the SBS modifier is divided into two types, the linear structure and the star structure. Experiments show that the effect of star SBS modifier is the best. But in terms of processing performance, the linear shape of the processing is much easier than the star. In the production process should be based on the matrix asphalt, processing technology to select the appropriate SBS modifier. My unit after the experiment, according to the grinding effect of colloid mill with their production process, the Yueyang Petrochemical baling brand SBS791 and SBS898 mixture, significant modification effect.

Selection of 2.3 stabilizers

Modified asphalt production