Study On Preparation And Performance Of Composite Modified Asphalt With HDPE- Desulfurized Rubber Powder

The research on crumb rubber modified asphalt in China began in 1980 s,and a lot of technical achievements have been achieved since then.Many practical projects have been constructed in Hebei,Hunan,Guangxi and other provinces,bringing excellent application results.But some problems were also exposed in early application of traditional rubber asphalt technology,such as the inadequate activity of rubber powder which would make it impossible to further increase the amount of admixture.Nevertheless,modified rubber powder with high surface activity can be obtained by using desulfurization technology,which can reduce the viscosity of modified asphalt and eliminate its odor to a certain extent during construction.Also,the high temperature performance of asphalt can be greatly improved by adding a certain amount of High-Density Polyethylene(HDPE)into it.Considering the characteristics of these two modified materials and the humid and hot climate in southern China such as Guangxi Province,the author of the thesis used self-made desulfurized rubber powder and HDPE as modifiers,and added them into asphalt to produce HDPE-Desulfurized Rubber Powder Composite Modified Asphalt by High-speed Shear Dispersion Emulsification Machine.Then,he synthetically explores the pavement performance of modified asphalt from the aspects of high temperature,low temperature,fatigue resistance and aging resistance.The main contents are as follows:Firstly,the traditional vulcanized rubber powder was desulfurized by using 480 activator and twin-screw extruder processing technology.Then,based on conventional indexes,such as three main indexes of asphalt,elastic recovery and viscosity,the author compares the advantages and disadvantages of desulfurized asphalt with 20% modifier content.Referring to the processing method of Vulcanized Rubber Asphalt,the modification effect of HDPE-Desulfurized Rubber Powder Composite Modified Asphalt and the reasonable proportion of the two modifiers were preliminarily determined through experiments.The modified asphalt samples were prepared by high-speed shear mixing method.Orthogonal test was carried out to study the effects of rubber powder mesh number,processing temperature,preparation time and shear rate on the performance of modified asphalt in the process of preparing it with high-speed shearing machine.The optimum processing process of HDPEDesulfurized Rubber Powder Composite Modified Asphalt were finally determined.Secondly,according to the optimum preparation process,the author carried out Brinell Rotational Viscosity Test,DSR test and BBR test of composite modified asphalt under proper addition range.The results show that HDPE-Desulfurized Rubber Powder Composite Modified Asphalt has excellent high temperature performance and temperature sensitivity under certain addition range,but the addition of HDPE modifier has adverse effect on the low temperature performance of desulfurized rubber asphalt.The high and low temperature performance,fatigue resistance performance and anti-aging performance of rubber-plastic composite modified asphalt are the best when the addition amount of desulfurized rubber powder and HDPE is 28%+2% respectively.Finally,according to the conventional aging performance evaluation index of asphalt,the author studied the aging properties of HDPE-Desulfurized Rubber Powder Composite Modified Asphalt and preliminarily evaluated its anti-aging effect.The results show that the anti-aging performance of modified asphalt can be improved by adding desulfurized rubber powder to asphalt,and the addition of HDPE can significantly improve the aging resistance of desulfurized rubber powder modified asphalt.