Stabilization of sandy soil with geopolymers based on nanomaterials and Taftan pozzolan

Today, Portland cement is used as the most common material for construction purposes and stabilizer forbuilding bases and substrates in civil engineering. However, engineers are looking for a replacement of cementdue to adverse environmental impacts. Geopolymer and alkali activated materials as environmentally friendlymaterials are a suitable alternative to cement. In this study, geopolymers based on Taftan natural pozzolan and nanomaterials (nanoclay and nanosilica) were used to stabilize sandy soil. Various parameters such as type ofnanomaterial, amount of nanomaterial, alkaline activator solution ratio and curing time were taken intoaccount as the affecting factors on the behavior of stabilized specimens. To evaluate the effect of geopolymerand nanomaterials on sandy soil stabilization, in addition to testing of the unconfined compressive strength(UCS) and the tensile strength, which is the main criterion for comparison of specimens, X-ray diffraction andscanning electron microscopy were performed to verify the microstructure of the stabilized soil. Based on thisstudy, natural pozzolan and nanomaterials are appropriate and beneficial alternative materials in stabilizationof earth structures. The results showed that the addition of pozzolan and nanomaterials to soil and increasingthe amount of alkaline solution caused an increase in the unconfined compressive strength and the tensilestrength of the soil and thus the soil stabilization. Additionally, the results of the microstructural analysisindicate a strong reaction of chemical additives and the formation of aluminosilicate gel in geopolymercompounds, which itself increases the load-bearing capacity of the soil and stabilizes it.