عنوان مقاله [English]
Portland cement is one of the most common materials for improving the mechanical properties of soils; while, it has many detrimental effects on the environment. Cement production releases millions of tons of carbon dioxide gas (CO2) to the air and uses millions of tons of raw material such as clay and limestone. For this purpose, geotechnical engineers are looking for using a new friendly environment material instead of cement. Geopolymers are new alternative stabilizers, which they have some advantage such as high resistance, long durability, and low cost. Two materials needed to prepare a geopolymer matrix are any materials that have silicate and aluminum oxide and alkaline activators. In this study, a geopolymer based on rice husk ash and iron ore tailings (IOT) are used for stabilizing sandy soil. Two types of alkaline activators are used, 1) Type I sodium hydroxide and 2) Type II carbide calcium residue. Various parameters such as type of material consumed, percentage of compound composition, type of alkaline activator, and processing time are considered as influencing factors on the behavior of the stabilized specimens. Unconfined compression tests and splitting tensile strength tests are used to evaluate the effect of these parameters on the mechanical behavior of the specimens. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis are performed to investigate the microstructures of the stabilized soil. The results show that adding the optimum amount of additives and handling the specimens under ambient conditions, the unconfined compressive strength of specimens increased. The optimum percentage is a combination of 10 percent of rice husk ash and 24 percent of iron ore tailings for activator I and 18 percent of iron ore tailings for activator II. The use of type I activator also indicates that it is highly effective for the formation of aluminosilicate gels in geopolymer compounds.