Hydro-mechanical properties of sludge stabilized with magnesium oxychloride cement-based multi-cementitious materials under influences of drying-wetting cycles

In order to investigate the long-term performance of "modified cured silt", which is a multi-phase cementitious material based on green magnesium chloride cement and supplemented by fly ash and slag as the industrial by-products, by further modifiying the initially cured silt as the roadbed filler, the soil-water characteristic curve (SWCC), rebound modulus (M_R), unconfined compressive strength (q_u), stiffness parameters (E_1% and S_u1%) and cumulative plastic strain (ε_p) of the modified cured silt in East Lake section of Wuhan are obtained through a series of tests after various drying-wetting cycles. The results show that: (1) The drying-wetting cycles produce a large number of macroscopic cracks and microscopic fissures in the modified cured silt specimens, which significantly reduce their water holding capacity in the low suction section, but have essentially no effects on the water holding capacity in the high suction section. (2) q_u, E_1%, S_u1% and M_Rrep all decay with the increasing N_DW, and their decay mechanisms are similar, and the decay factor (χ_DW)- N_DW relationship model is established accordingly. (3) After undergoing the drying-wetting cycles, the sensitivity of M_R to changes in the periapical pressure (σ_c) increases, whereas two different responses to the bias pressure (σ_d) are observed. (4) ε_p of the modified cured silt specimens that do not undergo the drying-wetting cycles exhibits a plastic stable type, while after undergoing the drying-wetting cycles, ε_p of the specimens transforms into a plastic transitional type at high σ_d and low σ_c levels