Improvements in the microstructural and mechanical properties of geopolymer concrete containing NMF’s of E-wastes as partial replacement of aggregates

Abstract

The information and communication revolution in the twentieth century has brought about massive changes in the living style and also economy. Although the quality of lives has been enhanced by these spectacular developments undoubtedly during the modern times, they have led to manifold problems in disposal of e-wastes. The annual generation of e-wastes globally is about 50 million tons, and according to recent studies, the quantity of e-wastes generated in India is 18.5 lakhs MT/year. Therefore, in order to protect the environment and create a sustainable livelihood, proper management of e-wastes is indispensible. Efforts are underway in the construction industry to use the non-metallic components of e-wastes, especially Printed Circuit Boards, as partial replacement for aggregates in concrete. A large portion of non-metallic materials in printed circuit boards (PCBs) are disposed off by disposal in landfill or combustion but it may lead to secondary pollution and wastage of resources. Geopolymer concretes have proved to greatly immobilise hazardous and radioactive wastes, thereby reducing their concentration and the impact on human and environment. Hence, this study aims to identify the possibilities of utilising the crushed PCBs as partial replacement for fine aggregates in Geopolymer concrete. It was observed that up to 30% replacement of crushed PCBs, the mechanical properties improved after which they were found to decrease. This increase in strength was significant at increased percentages (50–75%) of GGBFS replacement in Geopolymer concrete. It is thereby suggested from this study that utilisation of crushed PCBs in Geopolymer concrete will not only reduce the requirement for conventional fine aggregates but will also help in immobilising the heavy metals thereby affecting the conservation of natural resources.