Sustainable lean concrete mixes containing wastes originating from roads and industries

Scarcity of natural aggregates and illegal dumping of wastes originating from roads and industries are the major challenges for a developing country. The present study is an effort to provide a sustainable solution to the aforementioned challenges by utilizing these wastes for production of subbase course of concrete pavements. In the study, the optimum proportion of reclaimed asphalt pavement (RAP) along with the optimum proportion of the various supplementary cementitious admixtures (SCM) such as flyash (FA), silica fume (SF) and sugarcane bagasse ash (BA) have been evaluated for productions of dry lean concrete (DLC) mixes. The effect of the higher amount of Portland cement on the properties of RAP inclusive DLC mixes was also investigated. It was observed that the hardened properties of DLC containing RAP are mostly depended upon the maximum dry density of the fresh mixtures. Inclusions of considered industrial waste, as part replacement of Portland cement, were found to have an insignificant effect, whereas, when included in excess of cement, enhanced the properties of RAP-DLC blends significantly. The results of the study depicted that the suitability of RAP aggregates for DLC subbase may be increased by increasing the cement content by about 50%, whereas, for achieving the comparable performance to that of DLC containing natural aggregates, the quantity of cement shall be doubled. Based on the results of different parts of the study, it is recommended to include at least 30% extra cement content with either of 10% SF or 20% FA for sustainable DLC mixtures containing 75% coarse RAP aggregates. (C) 2019 Elsevier Ltd. All rights reserved.