Strength Development of Cemented Soil Cured in Water-Air Conditions at Varied Temperatures: Experimental Investigation and Model Characterization

Curing temperature and curing mode could affect the mechanical properties of cement-stabilized soil, which is of both scientific and practical importance for cement mixing performance. This paper aims to present the strength development of cemented soil cured in a water and 95% relative humidity (RH) environment with a series of curing temperatures (T) based on laboratory tests and model characterization. The base soil was low-liquid-limit organic clay (OL) classified by the Unified Soil Classification System (USCS). Unconfined compression (UC) testing was conducted in this study, and a combination of Fourier transform infrared spectroscopy (FTIR), scanning electronic microscopy (SEM), and energy-dispersive spectroscopy (EDS) was used to further investigate the microcharacteristics of the stabilized specimens. Results showed that the unconfined compressive strength (UCS or qu) of cemented soil increased with the increment of temperatures T both at early (7 days) and long-term (90 days) curing periods. Nevertheless, the cemented soil cured in 95% RH mode constantly achieved higher strength compared with that cured in water. The q(u) of 28 and 90 days gained in 95% RH mode can be taken as 1.2-1.5 times and 1.4-2.0 times of that in the water bath. In addition, the crossover effect was observed in samples cured in water when T reached 80 degrees C, which was verified by the decalcification of calcium silicate hydrates (C-S-H) formed inside cemented soil through microtests. Based on the observations, a modified hyperbolic model characterizing the strength development of samples was proposed, in which the effects of curing temperature and curing time could both be considered regardless of the crossover effect. Moreover, the failure pattern of samples under different curing conditions was also analyzed. The findings presented in the current study are expected to provide insights and references for cement mixing engineering design.