Effect of waste foundry sand addition on strength, permeability and microstructure of ambient cured geopolymer concrete

Increasing urbanization and industrialization is raising burden on existing natural resources used in construction industry which is leading to severe environmental issues. Using industrial waste materials in construction can be one alternative to curb this problem. Geopolymer concrete (GPC), known as the next generation of concrete, is more durable and environment friendly as compared to conventional concrete. The current investigation presents the effect of waste foundry sand (WFS), a by-product of foundry industries; on low-calcium fly ash based GPC. The WFS was replaced by natural sand in the range of 0% to 100%. Tests on hardened concretes, such as, compressive strength, split tensile strength and sorptivity were conducted to evaluate the strength as well as permeability of ambient cured geopolymer concrete. Results indicate consistent decrease in workability of concrete with increase in WFS content but its inclusion improved the strength as well as decreased the sorptivity of concrete upto 60% replacement level of WFS. Maximum enhancement of approximate 43% in compressive strength was achieved in the GPC with 60% replacement by WFS. The results are validated by conducting SEM study. (paper)