Impact of Aeration and Curing Periods on Shear Strength of Asphalt Stabilized Soil

Abstract

The subgrade soil is the foundation for the roadway structure, its responsibility is to provide the required stability for the overlaying pavement and to limit the deformation due to traffic load repetitions by furnishing homogeneous stress distribution layer. Asphalt stabilization technique is usually used to control and improve poor subgrade soil condition. In this work, the unconsolidated undrained Triaxial test was implemented for comparatively assessing the impact of asphalt stabilization on shear strength and stiffness of asphalt stabilized subgrade soil. Soil samples have been treated with cutback asphalt using various water and liquid asphalt percentages. The loose asphalt stabilized soil samples were subjected to aeration periods ranging from one to five hours at room temperature of 20 ± 2 °C before compaction. Cylindrical Specimens with height and diameter of (77.4 and 38) mm respectively have been prepared in the laboratory after aeration periods using static compaction to achieve a target density. The compacted Specimens have been subjected to curing at room temperature of 20 ± 2 °C for a curing period ranging from seven to ninety days, then tested in the Triaxial apparatus to determine the shear strength and modulus of elasticity properties. Data were analyzed and compared. It was concluded that the optimum aeration period was two hours while the reasonable curing period is seven days. It was observed that the shear strength and the modulus of elasticity increases by (211 and 251) % respectively with increasing cutback asphalt percentage up to 8% asphalt content, as compared with natural soil. It was concluded that the effect of variation in fluid content in the range of 0.5% above or below the optimum has increased the shear strength by (663, and 662) % respectively as compared with natural subgrade soil.