Study On The Aging Behavior And Mechanism Of Paving Asphalt

Owing to superior performance and driving comfort, asphalt pavements account for a large proportion in highways and city roads. However, after aged by the natural environment, physical and mechanical properties of asphalt mixture will become worse until it can not meet the requirements of the traffic load. Thus, the aging of the asphalt is an important factor affecting performance and durability of pavement. Behavior characteristics and mechanism of the asphalt aging are researched and reasonable evaluation method of anti-aging performance of asphalt is advanced.First of all, aging characteristics of asphalt pavement in the natural environment are researched and influences of time, pavement depth and volume of air voids on aging process of asphalt pavement are given. In order to probe into influences of explore oxygen, heat, light and other factors affecting asphalt aging further, three are five kind of aging simulating tests containing three thermo-oxidative tests (RTFOT,PAV and oven aging at 60℃), thermal aging test without oxygen and UV aging. Result of analysis shows that the thermo-oxidative aging is the main form of pavement aging. The effect of RTFOT,PAV and oven aging at 60℃has a good relationship each other. What's more, natural aging in the field has similar effect with simulating aging tests in the laboratory. So the delay RTFOT can well simulate asphalt long-term aging.The decrease of asphalt properties led by aging is the external appearance of micro structural changes. Analysis of aging asphalt composition and infrared spectroscopy show that there are different characteristics about different aging method. But the mechanism of thermo-oxidative is the same, which is the course of chemical bond rupturing and oxygen increasing. Polar and hydrophilicity of asphalt enhance after aging. Therefore water damage of asphalt pavement and asphalt aging promote mutually.The high temperature properties of asphalt mixture will increase because of asphalt aging, but low-temperature properties and water stability have a remarkable decline. This the main reason for lack of durability of asphalt pavement. On the basis of asphalt aging in the field and in the laboratory, evaluation methods of asphalt aging resistance based on viscosity and ductility of aged asphalt, which can provide a theoretical basis for pavement maintenance.