Stabilizing cohesive soils with Micro- and Nano- fly ash as Eco-friendly Materials: An experimental study

Soil stabilization is a popular technique for improving soil properties and creating sustainable and green buildings using rammed earth walls. Nano materials are a new type of additive that can enhance soil performance. Laboratory tests were performed to examine the geotechnical properties of clay mixed with nano fly ash. Scanning electron microscopy (SEM), X-ray fluorescence (XRF), and X-ray powder diffraction (XRD) were used to analyze the nature and changes of the particles before and after the grinding process. The effect of time and different dosages of nano fly ash (3%, 5%, and 7%) on the curing behavior was also investigated. The test results showed that the optimal amount of nano fly ash and fly ash added to soil was 7% by weight of soil after 28 days. This increased the unconfined compression strength of clay from 50 kPa to 410 kPa (8.2 times) and the triaxial strength of clay from 65, 80, and 90 kPa to 520, 640, and 720 kPa (8 times) respectively. The results showed that nano-fly ash as a nano soil-improvement suspension significantly improved the strength and stiffness of the soil-fly ash mixture by forming gel that filled the pores and bonded the soil particles. Nano-fly ash also acted as a nucleation site, enhancing the durability and strength of the mixture.