Performance of Granular Volcanic Ash-Cement-Fine Soil Mixture for Sub-Base Coarse of Road Pavement in Yemen

Abstract

Granular Volcanic Ash (GVA) is a material of volcanic activity characterized by a rough surface, low specific gravity, non-plasticity particles with poor gradation, and high porosity because of its mineral structure. This study aimed to evaluate the performance of GVA-cement-fine soil mixtures as a sub-base material for flexible pavement in Yemen. GVA was blended with fine soil at 0%, 10%, 20%, and 30% by dry weight of GVA to improve gradation and reduce the required cement. The mixtures were stabilized with 2%, 5%, and 8% cement by dry weight of GVA. Performance was assessed through compaction characteristics, unconfined compressive strength (UCS), indirect tensile strength (ITS), wetting-drying durability, and ultrasonic pulse velocity (UPV) on samples cured for 7 and 28 days. The results revealed that the applied compaction energy reduced the fineness modules of the coarse GVA by 23%. Increases in cement content and curing time produced higher UCS, ITS, and UPV values. The GVA-cement-fine soil mixture met the strength and durability requirements for a sub-base for medium-traffic roads when GVA contained 20% fine soil and was stabilized with 5% cement.