Laboratory Investigation on Healing of Sand Asphalt Mixtures

Asphalt is a complex civil engineering material. Asphalt when mixed with granular aggregates exhibits wide range of responses. "Healing" is one such mechanical response wherein if the material is allowed to rest after certain number of load applications, the material exhibits a "beneficial internal structure change". In this investigation, repeated triaxial tests were carried out on sand asphalt mixtures with varied confinement conditions and rest periods to quantify healing of asphalt mixtures in the laboratory. Two parameters were identified to quantify healing. The first parameter corresponds to the percentage change in instantaneous deformation before and after rest period. The second parameter corresponds to the percentage change in strain recovery at a fixed time period after unloading. The influence of various testing conditions on these two parameters is investigated.