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.