Executive Summary : | The huge infrastructure development demands for utilization of huge quantities of concrete and hence the Portland cement. The cement industry produces about 5% of global man-made CO2 emissions, of which 50% is due to the chemical process, and 40% is due to the burning of fossil fuels. Hence the research focus is on the development of alternate binders replacing cement that leads to the development of geopolymer concrete which used industrial wastes as the source materials for the making of concrete. On the other hand, Construction and demolition (C&D) waste generation and handling issues have been in focus to achieve sustainable goals and the reuse of recycled material has now been mandated by the Construction and Demolition Waste Rules and Regulations, 2016. Based on literature study, it has been found that properties of recycled concrete are inferior in terms of low compressive, tensile, and flexural strength as well as high water absorption, porosity, and shrinkage which is attributed to the heterogeneous nature of the recycled aggregates caused by the attached old mortar that is characterized by high porosity, microcracks, and flaws which make the particles of the recycled aggregates weak and hence leads to loose microstructure. Many attempts have been made by the researchers to improve the properties of recycled aggregates by separating the old mortar that is attached to the surface of the aggregate that resulted in drawbacks such as energy consumption, compromising durability aspects, and high cost. Considering the above drawbacks, this project is aimed to develop an eco-friendly and economic solution for the complete recycling and utilisation of waste concrete, both waste concrete powder and recycled aggregates in concrete production. The waste concrete powder will be used in combination with fly ash and or Ground Granulated Blast Furnace Slag (GGBS) to produce geopolymer mortar with desired properties. The recycled aggregates with old mortar adhering to them will be geopolymerised partially to develop a good bond between the aggregate and mortar. It is proposed to optimise the quantities of concrete waste powder, fly ash, GGBS, recycled fine aggregates and recycled coarse aggregates for preparing geopolymer concrete by identifying the various parameters that affects the mechanical and durability properties of geopolymer concrete. Initially, the mechanical properties of mortar produced from waste concrete powder, fly ash and GGBS will be investigated and then the bond behaviour between recycled aggregates and geopolymer mortar will be studied. As a next step, the mechanical behaviour of geopolymer concrete with recycled aggregates and waste concrete powder and Fly ash/GGBS will be investigated. Based on the results of the studies, it is proposed to give suitable design guidelines to provide set of recommendations for the designers to design structural elements or systems using recycled materials derived from C & D waste. |