Abstract
The purpose of this paper, based on the amount of ultraviolet (UV) radiation in different areas of China, was to give the corresponding measures to prevent UV aging of asphalt. In this paper, based on the average annual amount of UV radiation in China in the past 30 years and the characteristics of UV aging of asphalt, the climatic zoning of UV radiation of asphalt in China was proposed. A variety of base asphalts and styrene–butadiene–styrene block copolymer (SBS) modified asphalts were selected to carry out a UV radiation test, and the relationship between UV radiation amount and viscosity, low-temperature performance, and the rheological properties of asphalt were studied. The equivalent aging indexes of asphalt during UV radiation were selected, the UV aging equation of asphalt was proposed, and the equivalent UV aging relationship among different UV climate zones was established. The prevention and control strategies of UV aging of asphalt among different zones were proposed, and the above theory was verified using a trial road. The main conclusions in the paper are presented: The climate zoning of asphalt UV radiation in China can be divided into three zones: zone I with an annual UV radiation less than or equal to 69.4 kW·h/m2 in the last 30 years; zone II with an annual UV radiation of 69.4~81.4 kW·h/m2 in the last 30 years; zone III with an annual UV radiation more than or equal to 81.4 kW·h/m2 in the last 30 years. The greater the amount of UV radiation, the greater the loss rate of penetration and ductility. For the same kind of asphalt, there is a relatively stable functional relationship between the loss rate and the amount of UV radiation. The results also show that UV radiation changes the proportion of viscous and elastic components in asphalt, showing that the proportion of viscous components decreases and the proportion of elastic components increases. The penetration loss rate and ductility loss rate of asphalt can be used as equivalent UV aging indexes of asphalt. Under the same outdoor UV irradiation time, for asphalt to achieve the same technical performance as zone I, the anti-UV ability of zone II needs to be improved by more than 5%, and that of zone III needs to be improved by more than 10%. Engineering practice has proved that the zoning established in this paper and the corresponding UV control measures are basically reasonable.
Highlights
The anti-aging performance of asphalt and asphalt mixture is an important factor affecting the service quality and service life of asphalt pavement
The direct effect of UV radiation is on the asphalt surface, considering the diffusion of asphalt molecules after aging and the existence of asphalt pavement voids, the actual effect of UV radiation on the asphalt surface can reach about 1 cm [5]
The anti-UV aging agent is used in trial section 2, and the other working conditions are basically the same
Summary
The anti-aging performance of asphalt and asphalt mixture is an important factor affecting the service quality and service life of asphalt pavement. The aging process and degree of asphalt in different structural layers of asphalt surface course are quite different, among which the aging of upper layer asphalt is the most serious [1,2]. The external temperature and traffic load on the pavement can be shared by each structural layer of asphalt pavement, but solar radiation, as a natural energy source, can only be borne by the surface layer of asphalt pavement alone [3,4]. UV aging results in an increase in low-temperature stiffness of surface asphalt mixture, from which it is very easy to produce temperature shrinkage cracking, increasing the depth of UV incidence. The aging effect of asphalt pavement materials caused by UV radiation cannot be ignored
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