Feasibility Study of Transforming Excavated Clayey Soil into ‘Sand-Like’ Material

Abstract

In order to upcycle clayey soil, which generally has poor strength properties, it was proposed to transform them into a more useable ‘sand-like’ material using sintering technology in this feasibility study. A muffle furnace was adopted to heat the clayey soil at different sintering schedules. The results showed that the well sintered ‘sand-like’ pallets had a friction angle (about 34–37°) in the same range as a typical medium dense sand. The sintered product’s permeability was found to be in the order of 1 × 10−3 m/s, which is similar to the gravel-sand mixtures category. The maximum dry unit weight and optimum moisture content in compaction behaviour were slightly lower than a typical silty sand-gravel. Mineralogy check and soil fabric check using X-ray diffraction (XRD) and scanning electron microscopy (SEM) showed that the kaolinite (weak mineral) had been transformed into metakaolinite (stronger mineral) in the ‘sand-like’ material. The sintered product was almost irreversible through the acid and saltwater dissolvability test. All the findings confirmed that it is feasible to produce “sand-like” material from excavated clayey soil through sintering technology.