Influence of Air Void on the Performance of Paved Rubber Asphalt Stress-Absorbing Layer

Abstract

To study the influence of air void on the performance of paved rubber asphalt stress absorption layer, two typical air voids, 2.5% and 4.0%, were selected. A high temperature rutting test, water immersion Marshall test, and freeze–thaw splitting were used to evaluate high temperature performance and water stability of the asphalt mixture, respectively. Trabecular bending test and SCB crack propagation test were used to evaluate the stress absorption performance. After reducing the air void from 4.0% to 2.5%, tests show that: the dynamic stability of the mixtures decreased, but the decrease range was less than 10%; the residual stability and freeze–thaw splitting strength ratio were improved; the increase range of flexural tensile strain and strain energy density at −10°C was 19.0%–46.6%, and the increase range is 2.1%–6. 7% at 15°C; the growth range of fracture energy of three gradation mixtures was 11.0%–17. 8%; and the growth range of flexibility index was 4.4%–40.0%. The results show that the evaluation results of different test methods are not consistent. The flexural tensile strain and strain energy density of trabecular bending test, fracture energy, and flexibility index of SCB crack propagation test should be used to evaluate the stress-absorption performance of asphalt mixture comprehensively. The small air void may reduce the high-temperature stability, but improve the water stability, low-temperature tensile performance, and stress absorption performance. Therefore, the design of paved stress-absorption layer with rubber asphalt has good application potential. When the designed air void was controlled at 2.0%–3.0%, it had better performance for the stress-absorption layer.