Evaluation of Durability and Dynamic Properties of Treated Silty-sand Soil as the Road and Runways Base Material

The present paper investigated the dynamic and durability characteristics of silty-sand soil used in the base layer treated with cement and a mineral polymer via a series of laboratory tests.The specimen selection for the cyclic triaxial test was based on the results of the uniaxial compressive strength, Brazilian tensile, wetting-drying and freezing-thawing cycles tests. The results showed that, the compressive strength of the cemented soil can be reached in the shorter period of times and volume loss of the cement specimen may be eliminated due to the use of polymer. The compressive strength of the treated specimen with 6.3% cement and 0.7% polymer and has been selected as the optimal combination. In the durability test, the cement-polymer specimens show a better performance than cement specimens, and this trend is more noticeable in wetting-drying cycles than freezing-thawing cycles. In the next step, the cyclic triaxial test was performed on four optimal combinations with treated cement and cement-polymer. An increase in frequency raises the resileient modulus and damping ratio, while it has decreased the axial strain. For AASHTO T307 stress level, the mean values of the resilient modulus of cement-polymer specimen were higher than cement specimen in two curing modes. Meanwhile, for damping ratio parameter, the cement specimen show a better performance than cement-polymer specimen. Generally, soil treatment with the cement-polymer specimen demonstrated a relative advantage over the cement-only specimen in the medium stress range for the base layer in wetting-drying mode (as defined by stress levels in AASHTO T307 standard).