Mechanical properties and environmental impact of rubberized fly ash- and red mud-based geopolymer concrete

The growing disposal of industrial waste materials and high CO2 emission of cementitious materials production are serious concerns since they can globally pose critical environmental problems. Therefore, the environmental impacts besides the mechanical properties of materials are one of the major factors that should be considered. This study aims to investigate the mechanical, microstructural, environmental and economic impacts of red mud (RM)- and fly ash-based geopolymer concrete (GPC) containing waste tire rubber. The mechanical characteristics of rubberized GPC were evaluated by destructive and nondestructive tests. The scanning electron microscopy and X-ray diffraction were used for microstructural investigations. The response surface method was adopted to determine the optimum concrete mixture based on desirable goals. The results indicate that the low content of rubber did not significantly change the mechanical properties of rubberized GPC. A slight enhancement in strength was observed by increasing the RM from 20% to 30% at 60% and 90% of rubber. Based on this study, rubberized GPC can be considered to be suitable and beneficial as a medium to low and controlled low strength material, since the incorporation of wastes led to the reduction of both CO2 emission and cost with desirable mechanical properties.