Cement-Improved Wetting Resistance of Coarse Saline Soils in Northwest China

Abstract

Wetting-induced collapse of coarse saline soil foundations is a frequently encountered problem in the inland basin of Northwest China, but this particular behavior and relevant treatment have not been given adequate attention. Specimens treated by silicate cement were used in wetting collapse testing at conventional foundation loads, with five cement contents and four curing durations considered. The results indicate that in the case of no curing, the collapsible deformation during wetting declines at higher cement contents, and a stepwise development of deformation was noticed over the wetting duration. Specimens treated by cement after curing exhibit a decrease in the compressive deformation during wetting, and part of them show volume expansion instead. The complex hydrolysis and hydration reaction of cement in the process of curing primarily accounts for this. Moreover, the collapsibility coefficient varies within a narrow range in the noncuring case, proving the limited influence of cement inclusion; however, a gentle range, from 2.0 to 4.0 %, can be found after curing, beyond which it slightly varies. An elastoplastic model was established, incorporating a variable boundary seepage equation, and was then used for modeling a field immersion test. The rationality of the model was verified by comparing the measured and simulated results, including the degree of saturation and vertical displacement. The optimal depth and width for cement treatment was discussed in view of the practical engineering.

Installation of Bored Piles with a Protective Silicate Shell of a New Design in Saline Silty-Clayey Soils

“…As for the ground improvement, the samples treated with silicate cement [26], geopolymers [27], and fly ash and slag [28] have shown reliable results in terms of collapsible deformations under loading in wetting conditions and soil stabilization in general. Thus, based on the experience of previous research, including personal contributions of the authors in this area [29], it was required to develop a progressive corrosion protection method that meets the design requirements of an aggressive saline soil environment satisfying SP RK 2.01-101-2013 [30] and, at the same time, increasing the bearing capacity and durability of bored pile foundations:…”