Effect of Seawater on the Mechanical Strength of Geopolymer/Cement Stabilized Sandy Soils

Abstract

Freshwater supply for stabilizing sandy soils is one of the significant challenges in coastal regions. On the other hand, Ordindary Portland cement (OPC) has several limitations in the exposure to saline environments. Geopolymers, as environmentally friendly soil stabilizers, have been widely used in soil stabilization research. In this paper, the effects of natural seawater (SW) on the mechanical and microstructural properties of Portland cement/geopolymer stabilized sandy soils were studied. The soil samples were prepared with freshwater as reference samples. The impacts of binder type, slag replacement, curing duration, and curing conditions on the mechanical strength of stabilized soil samples were investigated. SEM images were used for microstructural analysis of the geopolymer stabilized soil samples. The results indicated that the use of seawater in stabilizing soil resulted in higher strength development in short-term (28 days) compared to the distilled water-based samples. However, seawater adversely affected the soil's long-term (90 days) strength. In addition, the strength of slag-based samples was generally higher than the strength of OPC and VA-based samples. Therefore, alkali-activated slag can be a potential replacement for OPC paste in stabilizing sandy soils. The SEM images revealed that using seawater led to the alteration of cementitious gels in comparison to distilled water.

Investigation of Cement and Fly Ash on the Improvement of Fine Sand Soil

“…It is known that moisture content affects the mechanical properties of soils by which the increment in water content reduces the mechanical properties of the soil. Some recent studies such as Ghadir and Razeghi [16] and Samadi et al [17] focused on the curing duration and curing conditions on the mechanical strength of stabilized soil samples.…”