Experimental Study On Dynamic Properties Of Fiber Reinforced Asphalt Concrete Under Impact Loading

As a widely used engineering material, asphalt concrete is supposed to quasi-static load as well as action of mobile load from explosion and impact and so on during working process. As a result, it is of great significance to study mechanical property of asphalt concrete under impact loading.This paper is focused on the research of dynamic behavior of asphalt concrete by using Split Hopkinson Pressure Bar (SHPB) with temperature control device. Impact compression tests were done with five different temperature (-20℃,0℃,20℃,40℃,60℃) and five different strain rate (50s-1,80s-1,110s-1,140s-1,170s-1) ranges for common asphalt concrete, and impact compression tests were conducted with various strain rates (50s-1,80s-1,110s-1,140s-1,170s-1) for modified asphalt concrete under the temperature of 20℃and impact compression tests were also done with three different strain rate (50s-1,110s-1,170s-1) ranges for fiber reinforced asphalt concrete, hence stress-strain curves of various specimens under different conditions were obtained from tests. From the test results, the dynamic behavior for different asphalt concrete were discussed and the effects of temperature and strain rate on the dynamic behavior for asphalt concrete were also discussed. At last, the dynamic compressive strength and toughness index were analyzed and compared for different asphalt concrete.The obtained results show that the mechanical behavior of asphalt concrete is sensitive to temperature and strain rate equivalently. It exhibits the characteristic of transition to "Glassy" in the stress-strain curve of common asphalt concrete under the low temperature, in dynamic condition. The obtained results indicate that the increasing rates of the strength and toughness index present the tendency of descending with'increasing strain rate for fiber reinforced asphalt concrete, even negative growth. In addition, fiber content exerts a significant influence on the dynamic behavior of asphalt concrete. At a polyester content of 0.25%, the compressive strength and toughness index reach maximum values; The compressive strength reach 39.4MPa when strain rates about 170s-1; Within the strain rate range of 0～0.03, about 170s-1 strain rate, the toughness index increase by 16.5% in comparing with that of the common asphalt concrete. All the fibers added can improve the dynamic properties of asphalt concrete. For improving compressive strength, polyester fiber is the best, lignin fiber the second and glass fiber the least; while for improving toughness index, polyester fiber is the best, glass fiber the second, and lignin fiber the least.