Stabilization of Shield Muck Treated with Calcium Carbide Slag–Fly Ash

Abstract

Solidifying shield muck with calcium carbide slag and fly ash as curing agents was proposed as a highly efficient method for reusing waste shield muck. The compaction test, unconfined compression test, and dry–wet cycle test were used to evaluate the compressive strength, water immersion stability, and durability of the cured soil. The stress–strain curve and microscopic test were employed to analyze the compression damage law, mineral composition, and microscopic morphology of the cured soil, and to analyze the mechanism of calcium carbide slag–fly ash-cured shield muck. It was found that calcium carbide slag–fly ash can significantly improve the compressive strength of shield muck, and the strength of cured soil increases and then decreases with an increase in calcium carbide slag and fly ash and increases with curing age. The strength was highest when the content of calcium carbide slag and fly ash was 10% and 15%, respectively. Dry–wet cycle tests showed that the specimens had good water immersion stability and durability, and the stress–strain curve of the specimen changed from strain hardening to strain softening after dry–wet cycles. The internal particles of the cured soil were mainly cemented and filled with C-(A)-S-H colloid and calcium alumina (AFt), which both support the pores between the soil and form a skeleton structure to enhance the strength of the soil and lend it good mechanical properties.