Evaluation of performance parameters of cement mortar in semi-flexible pavement using rubber powder and nano silica additives

Abstract

Semi-flexible pavement offers a high bearing capacity and resistance to rutting. It comprises a layer of cement mortar and one of porous asphalt and is subject to thermal cracking because of the difference in stiffness of these materials. In this study, rubber powder (RP) was used to approximate the stiffness of the cement mortar relative to porous asphalt concrete in order to reduce thermal cracking. Nano silica (NS) was used to reduce the negative effect of RP on the compressive and flexural strength. The effects of these additives on the behavior of 20 mortar mixtures were investigated by mechanical testing and scanning electron microscopy. The results showed that 0.5% to 1% NS can prevent the fluidity loss and increase the drying shrinkage in the matrix. Three of the best-performing mortars were rated, and the optimum mixture was NS1-RP5 containing 1% NS and 5% RP. With an elastic modulus loss of about 20%, it exhibited the best performance and mechanical properties.