Principle analysis of the mix design and performance evaluation of the asphalt-filler volume equivalent substitution method

The asphalt mixture designed with the Marshall mix design method has stable quality and convenient technical management, but the design range of the asphalt-aggregate ratio is small and difficult to adjust, and is therefore difficult to adapt to the design of functional pavement materials with different requirements. In order to solve these problems, the asphalt-filler volume equivalent substitution method (the volume equivalent substitution method) has been proposed. Based on the optimum asphalt-aggregate ratio of the Marshall method, the asphalt-aggregate ratio in the mixture is increased by the equal volume substitution of asphalt and filler. The increase in the asphalt volume is equal to the decrease in the filler volume, and vice versa. With the condition of constant aggregate gradation, the modified asphalt of asphalt mixtures with filler contents of 6.0%, 4.5%, 3.0%, 1.5%, and 0% is designed based on the AC-13 gradation. Based on this, a high-temperature stability test, a low-temperature crack resistance test, a four-point bending fatigue test, and other tests are carried out for the asphalt mixtures. The results show that the dynamic stability of each mix proportion designed with the volume equivalent substitution method is 4924 times/mm even under the most unfavorable conditions (the filler dose is 0%). The maximum bending tensile strain of the specimen with a 0% filler dosage can reach 9667 μ, which is more than twice that of the specimen with a 6% filler dosage. The fatigue test shows that increasing the asphalt content in the mixture is beneficial for improving fatigue durability. The research results show that the material designed by the volume equivalent substitution method has excellent road performance in each proportion. This paper provides a method for the flexible adjustment of the asphalt-aggregate ratio and the asphalt mixture comprehensive road performance. Using this method, the optimum asphalt-aggregate ratio needs to be determined comprehensively according to the stress characteristics and functional requirements of the pavement and the pavement performance index of the mixture, and further research is still needed.