Soil-Recycled Aggregate-Geopolymer Road Base/Subbase Mixtures: Steps Towards Sustainability

This study deals with the development of Soil-Geopolymer mixtures using flyash, alkali activator and recycled aggregates (RAG) including recycled concrete (RCA) and reclaimed asphalt (RAP) as an alternative to soil-cement for pavement base and subbase layers. Several mix constituents were varied such as flyash type and content, RCA and RAP content and ratio of sodium silicate and sodium hydroxide. Experiment design was established and mechanical and durability characteristics of Soil-RAG-Geopolymer mixtures were evaluated and then compared to the conventional soil-cement mixtures. The results of the testing showed that for the selected Soil-RAG-Geopolymer mixtures the strength, stiffness, permanent deformation, and durability characteristics were either comparable or better than the soil-cement mixtures. However, such mixtures required more curing time at room temperature to achieve needed strength. In order to further optimize the practical applications of this technology in the field, other variables such as molarity of alkali activator, curing conditions, early strength development at room and ambient temperatures, gradation of RAG and shrinkage characteristics need be investigated.Tran-SET Project No. 18GTLSU1