Stabilization of Amol fat clay using seashell ash

One of the methods used to improve the physical and mechanical properties of problematic soils is chemical stabilization. This study appraises the eventuality of using seashell ash (SSA), to enhance engineering properties of the fat clay. For this purpose, samples were prepared at five different contents of SSA (i.e., 0, 3, 6, 9, and 12% by dry weight of the soil) and four various curing periods (i.e., 1, 7, 14, and 28 days). Compaction, unconfined compressive strength (UCS), and unconsolidated-undrained triaxial tests, X-ray fluorescene, and scanning electron microscopy analyses were performed to determine the compaction characteristics, compressive strength and durability, shear strength parameters, and mineralogical and microstructural variations in stabilized samples. Based on the results and considering the energy-saving and time, it was recognized that the appropriate time and temperature for the incineration of SSA in this study were set to 1 h and 900 °C, respectively. Results showed that SSA can considerably enhance the strength and durability of the fat clay. The highest UCS enhancement is obtained with 9% SSA and then decreased. Furthermore, with increasing moisture content, the UCS increased in the SSA-stabilized samples, unlike in the case of unstabilized clay. The shear strength parameters increase with increasing SSA contents. Microstructural analyses indicated that the addition of SSA had a major impact on the structure of stabilized samples. Adding SSA by covering the particles and filling the pores between them causes a stiffer and denser structure. Finally, the results of this study corroborate the effectiveness of SSA as a nontraditional additive for soil stabilization.