Geotechnical Properties of Waste Excavation Rock in Pavement Subbase Applications

Abstract

This paper presents the findings of an extensive laboratory investigation on the geotechnical properties of waste excavation rock in pavement subbases. The waste excavation rock used in this study originated from “basalt floaters,” or surface excavation basalt rock (basalt). Traditionally, this material would have been disposed as waste, often into landfill. The engineering properties of the crushed basaltic waste rock were compared with the local road authority specifications to assess its performance as a pavement subbase material. The experimental program was extensive and included tests such as particle size distribution, modified Proctor compaction, particle density, water absorption, California bearing ratio, Los Angeles abrasion loss, pH, organic content, static triaxial, and repeated load triaxial tests. The Los Angeles abrasion loss value obtained indicated that the crushed basaltic waste rock is durable. California bearing ratio values were found to satisfy the local state road authority requirements for a subbase material. Repeated load triaxial testing established that the crushed basaltic waste rock would perform satisfactorily as a pavement subbase material in the field. The results of the laboratory testing undertaken in this research indicated that crushed basaltic waste excavation rock satisfied the criteria for use in pavement subbase applications.