Soil-Geopolymer Mixtures Using Recycled Concrete Aggregates for Base and Subbase Layers

Abstract

The recycling of concrete aggregates has become a viable venture to investigate particularly its application in road construction. This study was conducted to proffer the feasibility of using recycled concrete aggregate (RCA) mixed with soil, flyash and alkali activator as an alternative to soil-cement in road base or subbase applications. The resulting product known as Soil-RCA geopolymer was made by varied mix constituents of flyash, RCA, sodium silicate, and sodium hydroxide. The influence of mixture variables on the mechanical properties of Soil-RCA geopolymer was investigated through an experiment design using two different flyash. Models to predict the unconfined compressive strengths based on mixture parameters were also established for the sensitivity analysis and selection of final mixtures. The results and analysis showed that the Soil-RCA geopolymer mixture exhibited sound strength, stiffness and durability characteristics.

Utilisation of Waste-Based Geopolymer in Asphalt Pavement Modification and Construction—A Review

“…The incorporation of geopolymers of less than 5% has an insignificant impact on the mixing and compaction temperatures. However, a significant increase was observed in the compaction and mixing processes when asphalt mixtures are modified with 5% of FA geopolymer [14,16,40].…”

“…One of the benefits of geopolymers is their high compressive and flexural strengths. The manufacture of geopolymers is carried out at an ambient temperature, emits less carbon dioxide, and uses inexpensive waste materials (FA, silica fume, various types of clays, and agricultural wastes) [16]. The consistency of FA properties is non-guaranteed because of the presence of contaminants such as iron and calcium.…”

“…The consistency of FA properties is non-guaranteed because of the presence of contaminants such as iron and calcium. Therefore, geopolymers are the critical resources for the future production of geopolymer asphalt [16,17]. Other precursor sources are raw material geopolymers and rocks with high aluminium oxide contents [18].…”