Effect of ultra-fine slag on mechanical and permeability properties of Metakaolin-based sustainable geopolymer concrete

The present study deals with the development of metakaolin-based geopolymer concrete (GPC) and thereafter studying the effects of adding ultra-fine slag on its mechanical and permeability characteristics. The mechanical characteristics including compressive, split tensile, flexural strengths and elastic modulus were studied. In addition, permeability characteristics including water absorption, porosity, sorptivity and chloride permeability were studied up to 90 days. The results showed the effective utilization of metakaolin for the development of elevated temperature cured geopolymer concrete having high 3-day compressive strength of 42.6 MPa. The addition of ultra-fine slag up to 15%, as partial replacement of metakaolin resulted in an increase in strength characteristics. Similar improvement in durability properties was also observed with the inclusion of ultrafine slag up to 15%. Beyond this optimum content of 15%, further increase in ultra-fine slag content affected the mechanical as well as permeability parameters in a negative way. In addition, the relationship between various properties of GPC was also derived.