SBS modified asphalt preparation process | FEITENG

Asphalt modification equipment principle

Modified asphalt technology and modified equipment is a technology with broad prospects for development, through the addition of a variety of polymers (i.e., modifiers) in the matrix without modification of asphalt, after sufficient grinding, mixing of the modification process, the production of asphalt and asphalt mixtures so that the performance of asphalt mixture has been greatly improved, asphalt mixtures - Modified asphalt.

Modified asphalt layout and production process

1. the matrix asphalt from the tank or drum off the device into the asphalt heating tank, heating to 170 ℃;

2. The warmed matrix asphalt and modifier according to the design ratio through the modified asphalt equipment on the metering pump and modifier delivery system, respectively, added to the modified asphalt equipment mixing tank 1, the side of the addition of materials and mixing, dissolving up to the pre-set amount. In this way, the mixing tank 1 will form a mixture of asphalt and modifier;

3. Open and close the corresponding asphalt valve switch on the control cabinet panel of the modified equipment (manual mode needs to be set manually, automatic mode is not necessary), start the colloid mill and frequency control pump, the asphalt mixture in the mixing tank 1 through the colloid mill grinding once again into the mixing tank 2, all milled shutdown;

4. And then the mixing tank 2 milled once in the asphalt mixture through the frequency control pump and colloid mill grinding once into the mixing tank 1, and so on repeatedly for a total of 3 to 6 times, you can get a good modified asphalt processing. Grind the number of times is based on each grinding once, through the modified asphalt after grinding indicators to test to achieve the required number of times to decide;

5. will be processed modified asphalt pumped to the modified asphalt storage tanks with agitators, in the storage of late development, that is, to become qualified modified asphalt, the general development of the late development takes about 1 to 2 hours.

6. In the case of on-site modification, development and storage tanks can share a tank. Modified asphalt storage tank can be directly connected to the mixing plant, with the use of pumping. At this time the modified asphalt storage time is generally not more than 24 hours, the storage temperature of 150 ~ 160 ℃ or so.

The comparison of modification methods

From the 1970s in Europe and the United States began to study the modified asphalt materials and modification process, there has been a modified asphalt production of direct input method, dissolution method, simple mixing method, the mother method, high-speed shear method and special colloid mill grinding and mixing method. Modifiers are mainly three categories: rubber (SBR, CR, EPDM, etc.), thermoplastic rubber (SBS, SIS, SBD, etc.), thermoplastic resins (PE, EVA, etc.). In the nineties, the U.S. Strategic Highway Research Program (SHRP) put forward a high-performance asphalt pavement system concept (Superpave), which starts from the “ultimate roadworthiness”, rather than the performance of the material itself, the production of modified asphalt as well as a series of new concepts and methods for performance analysis.

In the following, the various modification methods are compared:

According to Superpave, modified asphalt made by the dissolution method, the direct input method and the simple mixing method simply do not meet the standards set forth in the specifications for modified asphalt and are therefore no longer used.

Masterbatch method is the first high-speed shear mixing or solvent method and other processes prepared and processed into a high dose of polymer modified asphalt masterbatch, and then in the field of modified asphalt masterbatch and matrix asphalt blending and dilution into the required dose of modified asphalt to use. Due to the use of parent asphalt and engineering use of the parent asphalt varieties are not consistent when there will be the matching of the solubility problem, as well as the unevenness of the second blending and other difficult to overcome, and due to the residual solvents will produce damage to the mixture, the modifier segregation is serious, etc., and is no longer in use.

The use of high-speed shear method to produce modified asphalt, shear machine speed, time and other parameters will affect the performance of modified asphalt, while high-speed shear will introduce a large number of air bubbles into the asphalt, modifier and asphalt will occur segregation phenomenon, and the existence of the shear dead space, modifier shear is not uniform, resulting in asphalt and modifier can not be mixed homogeneously, and thus this method of production of modified asphalt there is a quality of unstable problems, quality It is difficult to meet the modified asphalt specification standards.

Because the above methods of production of modified asphalt can not reach or can not fully meet the requirements of the specification, the use of colloid mill to prepare high-performance modified asphalt. The basic principle is to add modifiers in the matrix asphalt, through high-temperature mixing and fusion and colloid mill grinding, so that the modifier particles to reach a smaller order of magnitude and uniformly dispersed into the matrix asphalt, the formation of a good modified asphalt.

Preparation process

Computer-controlled all-electronic measurement of asphalt modification equipment, accurate control of the dose. High degree of automation, the asphalt, modifier using electronic computer measurement, to overcome the asphalt weight changes and modifier manual weighing of the adverse effects brought about by the intelligent control of the computer, especially in the addition of matrix asphalt at the same time as adding modifiers, and effective mixing, so that the asphalt and modifiers in the colloidal homogenizing mill has been fully mixed before entering the homogeneous and modifier oil-filled rate is high, good swelling It overcomes the disadvantages of uneven feeding, swelling lumps and difficult grinding by hand, ensures that the modifier has sufficient swelling time and correct swelling temperature, and inhibits the heating of the colloid mill, avoiding unfavorable situations such as degradation of the modifier by the heating of the colloid mill. Equipped with temperature-adjustable development tank, so that the mixture continues to develop at the most suitable temperature, the polymer is uniformly distributed in the asphalt medium in the state of discrete phase as a fully continuous phase, so that the polymer modifier forms a stable and elastic network structure, in order to achieve the purpose of improving the modification effect and inhibiting segregation.

The number of grinding can be selected from full grinding once to complete grinding six times, complete grinding to overcome the probability of the average number of times of grinding, so that the modifier can be fully milled and dispersed, the average fineness of the modifier particles is less than 3 μm. after grinding the set number of times, through the asphalt pump P2 will be pumped into the finished product development of the asphalt storage tank T4, the finished product development of the tank is equipped with a heated and heat preservation and stirring anti segregation device, under the action of the stirring anti segregation device, the modification effect will be improved, and to improve the modification effect. Under the action of the stirring anti-separation device, the modified asphalt continues to develop, so that the polymer modifier forms a stable and elastic network structure, with better performance.