Influence of Curing on Deformation of Asphalt Stabilized Subgrade Soil

Abstract

Soil stabilization with liquid asphalt binder can enhance the required strength properties of the subgrade after proper curing period to allow for evaporation of volatiles from the binder. In the present assessment, an attempt has been made to stabilized subgrade soil with cutback asphalt. Specimens of 100 mm diameter and 63 mm height have been prepared at optimum cutback asphalt requirement and at 0.5 % cutback higher and lower than the optimum. Specimens were separated into two groups. The first group was cured for seven days at the laboratory environment while the second group was cured for 30 days. Both groups of specimens were subjected to repeated double punching shear application for 1800 load repetitions at the Pneumatic Repeated Load System (PRLS) at 20°C. The deformation variables (total, resilient and permanent) were monitored by Linear Variable Differential Transformer  (LVDT). It was observed that the total deformation after 30 days curing declines after one load repetition by (25 and 20) % for (16.5 and 16) % Cutback respectively when compared to the mixtures after seven days curing. The resilient deformation at failure declines after 30 days of curing by (1.2, 15.5, and 8) % for mixtures with (16.5, 16, and 15.5) % cutback asphalt respectively as compared with mixtures practiced seven days of curing. Asphalt stabilized mixture with 16 % cutback exhibit lower permanent deformation of 71.5 % after 30 days curing as compared with that mixture cured for seven days. It was concluded that curing period is vital in the gain of resistance to deformation of asphalt stabilized subgrade soil. The resilient deformation is (2 to 7) folds higher than the permanent deformation for asphalt stabilized soil and increases as the binder content rises.