The Research On The Effect Of Dacite Moisture Sensitivity To The Optimum Bitumen-aggregate Ratio Of Asphalt Mixture

Our country present specifications " Technical Specifications for Construction of Highway Asphalt Pavements " (JTG F40-2004) stipulate that the percentage of water absorption of coarse aggregate which used in freeway asphalt pavements is not bigger than 2.0%.During the GuangXi Nanning-Youyiguan freeway construction practice,dacite were used as surface aggregate. There were some questions such as water absorptivity is bigger,surpasses the limited value 2% ,and density is lower than normal aggregate. To solve the engineering practice problem,and supply with some practices for application of bigger water absorptivity aggregate in freeway construction,this paper carries on a series of laboratory tests research,including several work as follows:The paper primarily uses water absorption experiments to analyze water absorption variability of GuangXi dacite,in order to find out the fact that dacite aggregate performance were within the existing regulatory requirements except the bigger water absorption.This paper analyzes the difference of water absorption between the antecedent and later aggregate,to find that water absorption of the later aggregate is bigger than that of the antecedent aggregate. Thus it will result in the variability of optimum bitumen-aggregate ratio of the asphalt mixture.This paper primarily uses orthogonal experiment to analyze the adverse effects made by the four factories,which is fiber consumption,water absorption,cement content,molding temperature,to the optimum bitumen-aggregate ratio of asphalt mixture,and compare with the degree of their adverse effects to get some effective measures to lower the adverse effects,such as add several fiber or lime.This research analyzes service performance improvement such as high temperature stability,anti-cracking ability at low temperature,water stability and fatigue performance after adding some wood fiber to the general asphalt mixture through laboratory tests,at the same time analyzes the mechanism of wood fiber affect the asphalt mixture.