Development and evaluation of a novel geopolymer based on basalt rock waste and ground granulated blast furnace slag

Increase in industrial and construction activities has led to an enormous rise in waste generation and its hazardous impacts on the environment. Quarrying of rocks and manufacturing of artificial sands for civil engineering projects leads to the dumping of rock waste dust, which is a source of landfill problems. Further, excessive energy requirements for cement manufacturing, higher greenhouse gas emissions and rapid depletion of natural resources have focused the research towards the development of environment friendly and sustainable materials such as geopolymers. In this paper, a novel geopolymer has been developed from industrial wastes such as basalt rock fines considering partial replacement with ground granulated blast furnace slag up to 30%. After a detailed mix-design investigation, the optimum molarity (M) of the sodium hydroxide solution was found to be 8 M whereas the optimum ratio (R) of sodium silicate to sodium hydroxide solution as 0.75. Unconfined compressive strength evaluation showed 7-day strengths up to 34 MPa, comparable to geopolymers based on conventional precursor materials. The scanning electron microscopy imaging of the specimens revealed a dense geopolymer gel formation resulting in a homogeneous microstructure. As a result, this innovative material produced can be used as an alternative, sustainable and cost-effective construction material.