关键词: 道路工程, 砾石, 复合改性剂, 砾石沥青混合料, 水稳定性, 黏附性

Abstract: With the development of highway construction and ecological awareness of environmental protection, high quality gravel is increasingly scarce. Although gravel is rich in resources, its application in asphalt surface is restricted by its acidity. In order to improve the adhesion of crushed gravel and asphalt as well as improve the water stability of the gravel asphalt mixture, the inorganic materials such as cement or lime and anti-stripping agent were used as composite modifiers. Therefore, the gravel asphalt mixture was modified in different ways, such as single mixing or compound mixing, in order to enhance the bond between gravel and asphalt. 14 kinds of single mixing and compound incorporation schemes were designed; the influence law of types and contents of modified materials on the water stability of gravel asphalt mixture was studied by residual stability and freeze-thaw test. Based on the pullout test, the effect of admixture on the adhesion between asphalt and gravel interface was studied. The results show that single or compound admixture can improve the water stability of the mixture, but the effect of compound admixture is more remarkable. The improving effect of adding 0.4% amount of AMRⅠ-type anti-stripping agent is better than that of adding cement and lime. The effect of mixing 0.4% AMRⅠ-type anti-stripping agent and 1% cement is best, whose freeze-thaw strength ratio (TSR) and residual stability are increased by 28.8% and 22.6% respectively. With the same dosage, the pullout force is the largest, and the adhesion between asphalt and gravel is the best. The research results are of great theoretical and practical value for the popularization and application of gravel asphalt mixture.

Key words: highway engineering, gravel, composite modifier, gravel asphalt mixture, water stability, adhesion