Effects of Cement and Mineral Polymer on Geotechnical Properties of Silty Sand as Base Material

This study examined the geotechnical behavior of silty sand soil treated with cement and cement-mineral polymer through a series of static and dynamic tests. Uniaxial Compressive Strength (UCS) and Indirect Tensile Strength (ITS) tests were conducted on specimens with varying amounts of cement and polymer (i.e., 5, 7 and 9% by weight). Based on the results of UCS and ITS tests, the optimal combination of 7% cement and 7% cement-polymer was selected. Subsequently, California Bearing Ratio (CBR), Freezing and Thawing (F-T), and Large-scale cyclic triaxial (LCT) tests were performed on the optimal combinations. The results indicate that the treatment improves UCS, stiffness, CBR, and durability. By adding the polymer, the maximum UCS of the cement treated specimen can be achieved in a shorter curing period. Moreover, when exposed to F-T cycles, the cement-polymer specimen exhibited improvements in weight loss (about 0.6%) as well as compressive and tensile strength (about 200 kPa) compared to the cement treated specimen. In the dynamic tests, the cement-polymer specimen outperformed the cement specimen at low to medium cyclic deviatoric stress levels (up to 275 kPa). However, at higher stress levels, this trend was reversed. This behavior can be attributed to the formation of microcracks and cracks due to growth of needle-shaped microcrystals in cement-polymer specimen. Additionally, the cement-polymer treated specimen experienced lower permanent deformation during cycling loading. Overall, the polymer additive proves to be more effective in treating the base layer that withstands low and moderate stress levels, making it a suitable complement to a portion of cement.