Abstract
As a natural modifier of asphalt, rock asphalt has been widely used to improve its thermal stability and aging resistance. However, the thermal cracking resistance of asphalt modified by rock asphalt is unsatisfactory. In order to improve the thermal cracking resistance in low temperature, two kinds of modifiers—styrene–butadiene rubber (SBR) and nano-CaCO3—were selected as the compound modifiers, and then implemented to improve the low-temperature performance of the binder. Then, compound asphalt modified by Buton rock asphalt (BRA) was chosen as the study subject. The thermal stability and aging resistance of asphalt modified by BRA, compound-modified asphalt by BRA/SBR, and compound-modified asphalt by BRA and nano-CaCO3 were determined to identify whether the compound modifiers in the asphalt would have a negative effect on the thermal stability and aging resistance of the asphalt. The dynamic shear rheometer (DSR) test was employed to evaluate the thermal stability. The thin film oven test (TFOT) and pressure aging vessel (PAV) were adopted to determine the aging resistance. The viscoelastic characteristics of asphalt with and without modifiers were revealed to evaluate the low-temperature crack resistance of asphalt modified by compound modifiers. The bending beam rheometer (BBR) creep test was conducted in three test temperatures in order to determine the creep stiffness modulus of the BRA compound-modified asphalt. The viscoelastic model considering the damage caused by loading was established; then, the creep compliance and parameters of the viscoelastic damage model were implemented to evaluate the low-temperature performance of the compound-modified asphalt. The results show that the compound modifiers have little negative effects on the thermal stability and aging resistance of asphalt. The thermal crack resistance of the compound-modified asphalt by BRA/SBR was the best, followed by the compound-modified asphalt by BRA and nano-CaCO3 within the three materials. The accuracy of forecasting the characteristics of compound-modified asphalt was improved by using the viscoelastic model and considering the damage effect.
Highlights
IntroductionDue to the characteristics of the axle load, heavy traffic flow, and traffic channelization of modern highway traffic, the requirements of road materials are constantly improved
The asphalt pavement structure is widely employed in most high-grade road projects
The results have shown that the rutting factor of the asphalt increased, and the rheological behavior of the asphalt at high temperature was dramatically varied with the increase of the mixing amount of Buton rock asphalt (BRA) in the asphalt [8]
Summary
Due to the characteristics of the axle load, heavy traffic flow, and traffic channelization of modern highway traffic, the requirements of road materials are constantly improved. The traditional asphalt materials and design methods [1,2,3,4] can no longer meet the requirements of the durability of asphalt pavement. In order to develop a new type of compound-modified asphalt with excellent thermal stability, low-temperature crack resistance, and good durability, it is necessary to study the performance of modified asphalt. BRA has been successfully applied to Chinese road construction for its advantages such as good pavement performance, simple construction technology, et al There are many studies on Buton rock asphalt
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