Effect of crumb rubber and nano silica on the durability performance of high volume fly ash roller compacted concrete pavement

In this study, response surface methodology (RSM) was used to evaluate the effect of partial replacement of fine aggregate with crumb rubber and the addition of nano silica by weight of cementitious materials on the durability performance of HVFA RCC pavement. The experiments were designed and analysis executed using the face centered central composite design method. After executing the experimental works, regression analysis was used to develop models for predicting the Vebe time and water absorption of HVFA RCC pavement. The analysis of variance for the developed models showed that the Vebe time and water absorption of HVFA RCC pavement can be predicted using quadratic model type with higher degree of correlation and predictability. The results of multi-objective optimization showed that an optimum HVFA RCC pavement with minimum Vebe time and water absorption values can be achieved with 17.09% crumb rubber as replacement to fine aggregate by volume, 50% fly ash as replacement to cement by volume, and 1.01% nano silica as addition by weight of cementitious materials. The experimental results showed that the Vebe time of HVFA RCC pavement increases with increase in partial replacement of cement with fly ash, and addition of nano silica. While the rate of water absorption of HVFA RCC pavement increases with increase in partial replacement of cement with fly ash, and increase in partial replacement of fine aggregate with crumb rubber, and decreases with the addition of nano silica by weight of cementitious materials. (C) 2018 The Authors. Published by IASE.