Quantitative test technology study on the mesoscopic strength parameters of the mineral aggregate contact surface of bituminous-stabilized macadam

Quantitative test technology on the mesoscopic strength parameters of the mineral aggregate contact surface of bituminous-stabilized macadam was studied. On the basis of the failure mechanism of the mineral aggregate contact surface, the HC-40 hydraulic force measurement device and the self-designed test die were used to apply tensile load on the contact surface of the mineral aggregate. The total tensile strength Rt of the mineral aggregate contact surface was calculated. The total tensile strength Rt was compared with the splitting strength RT of the AM-20 Semi-Open-Graded bituminous-stabilized macadam mixture under different conditions. A corresponding calculation method was used to determine the adhesion strength Ra between the aggregates and bitumen, as well as the cohesion strength Rc of the bitumen binder itself. The results show that despite the small difference in numerical value between the total tensile strength Rt of the mineral aggregate contact surface and the splitting strength RT of the mixture, the variation law is consistent. The method of calculation adopted in the present study can provide the quantitative test for the adhesion strength Ra and the cohesion strength Rc at different states. The mesoscopic parameters of the mineral aggregate contact surface can directly affect the macroscopic strength parameters of the mixture. The test can promote the study on crack resistance and raveling resistance abilities of bituminous-stabilized macadam mixtures.

► The failure forms of contact surface include adhesion failure and cohesion failure.
► The microscopic strength parameters of contact surface include Rt, Ra and Rc
► Cohesion strength has nothing to do with the thickness of the oil film.
► Adhesion strength has relationship with temperature and oil film thickness.
► Achieve quantitative test of microscopic strength parameters of contact surface.