The mechanical properties of recycled solidified soil from underground construction spoils

Abstract: To address the challenges of managing and mitigating the environmental impact posed by the large amount of underground residual soil generated during underground construction, a composite material known as recycled solidified soil (RSS) was developed using this underground construction residual soil. Through a series of laboratory tests, including mix design, slump spread, unconfined compressive strength, and X-ray diffraction, the basic properties and regenerative curing mechanism of RSS were investigated under various curing conditions, water-tosolid ratios (the total mass ratio of water to air-dried residual soil and cementitious material), cement mass fractions and mineral admixtures. The results show that the fluidity of the RSS can meet the requirements of general backfilling projects at a water-to-solid ratio of 0. 35. The unconfined compressive strength of the RSS increases with curing time, higher cement mass fractions and water-to-solid ratios under different curing conditions, with lower strength of underwater curing compared to indoor curing. The establishment of strength in the RSS is primarily attributed to the cementation between hydration products and soil particles. The findings of this study offer valuable insights into the treatment and resource utilization of engineering residues and serve as a reference for addressing these challenges.