Assessment of strength development of soil stabilized with cement and nano SiO2

In consideration of the significant negative impact of ordinary Portland cement (OPC) on the environment, the use of nanomaterials as an additive to mitigate the amount of cement and enhance the physical and mechanical properties of cemented soil has been introduced. However, the existing empirical formulae to evaluate the strength of cemented soil with nano SiO2 additive are limited. This study aims to investigate the strength behavior of cemented soil with OPC and nano SiO2 additive through a series of unconfined compressive tests. The cemented soils with varying cement content (3 %, 5 %, 10 %, and 15 %) and water content (1LL, 1.2LL, and 1.5LL) were mixed with 0 %, 2 %, 4 %, 6 %, and 8 % nano SiO2. The unconfined compressive strength (UCS) of the cemented soils with nano SiO2 was measured at 7, 14, 28, and 56 days. Empirical models were developed to estimate the UCS of cemented soil with nano SiO2 additive. The results indicate that the incorporation of nano SiO2 can effectively improve the strength of cemented soil. The UCS decreases rapidly with an increase in the ratio of water to content (wc/c) values when the wc/c value is less than 7, while the trend of decreasing UCS stabilizes when it exceeds 7. The developed empirical models based on Gallavresi's formula can predict the UCS of cemented soil with nano SiO2 at different curing ages from the early strength on Day 7. The average MAPE value at different curing ages is 7.37 % by comparing the experimental value with the calculated value from the empirical model, demonstrating that the developed model has good predictive ability.