Preparation And Properties Of Crumb Rubber Compound Modified Asphalt For Waterproofing Membrane

With the development of construction industry, the demand of building waterproof materials is more strict and polymer modified bitumen waterproofing membrane is recognized as one of the high quality waterproofing material for its excellent properties. But the application and extension of polymer modified bitumen waterproofing membrane is restricted to some extent because of its high cost. At the same time quantity of output of waste rubber is increasing rapidly as the developing of automobile and the effective utilization of waste rubber is more and more important. Waste rubber is crumbed into powder and crumb rubber modified asphalt is prepared by adding rubber powder to asphalt, by which it can pretect the environment effectively. But single crumb rubber modified asphalt can't meet the performance standard, if compound modified asphalt which is prepared by adding little SBS or APP to crumb rubber modified asphalt can meet the performance standard and it can reduce the cost of polymer modified bitumen waterproofing membrane availably and pretect the environment, which will have important significance in economy, society and environment.In this paper crumb rubber modified asphalt was prepared by the method of blending at their melt and the effect of process conditions on the properties of modified asphalt was studied. The results showed that suitable process conditions were that rubber powder and asphalt was mixed under 215℃until 40min with shear speed of 4000rpm. The effect of crumb rubber powder on the properties of modified asphalt was researched and the results showed that as the content of crumb rubber powder increasing, the penetration of crumb rubber modified asphalt was reduced, softening point and elastic recovery were increased, but when the content of crumb rubber powder was more than 20%, the improvement of properties of asphalt was decreasing.Based on the conclusion of research above, two types of crumb rubber modified asphalt coating were prepared by incorporation of talc powder or coal ash into modified asphalt, the physical properties of modified asphalt coating and aging resistance were investigated. The results showed that the penetration, softening point and elastic recovery of modified asphalt coating with talc powder were more than that of coating with coal ash at the same content of filler. Also, modified asphalt coating by incorporation of talc powder had better aging resistance. However, the high temperature performance and low temperature flexibility of crumb rubber modified asphalt coating were poor that it couldn't meet the performance standard, therefore the high and low temperature performance can be improved by adding little polymer to crumb rubber modified asphalt coating.In order to improve the high temperature performance and low temperature flexibility of crumb rubber modified asphalt, compound modified asphalt was prepared by adding SBS to crumbrubber modified asphalt. The effect of of different kinds of SBS on the properties of rubber modified asphalt and aging properties of compound modified asphalt were investigated respectively. The results showed that branched SBS exhibited greater effect on the physical properties than linear SBS. After thermal aging and ultraviolet aging, the results indicated that compound modified asphalt with branched SBS had better aging resistance.The properties and aging properties of compound modified asphalt coating with APP, and the effect of different types of filler on the properties of coating were studied. The results showed that as the content of APP increasing, penetration and elastic recovery were reduced, softening point was increased, low temperature flexibility was increased first and then was reduced. Compared to talc powder, the effect of coal ash on the physical properties of coating was more obvious. After thermal aging, the results indicated that compound modified asphalt coating with coal ash had better aging resistance.