Micro-structural and metal leachate analysis of concrete made with fungal treated waste foundry sand

Abstract

Waste foundry sand (WFS) is a byproduct of metal casting industry which results from the mold and core making processes. Land filling is not considered to be a good option because it leads to the risks associated with the environment as it generates leachate which may contain heavy metals and organic contaminants. Its beneficial use in construction materials results in reducing the cost of construction materials’ ingredients and also helps in reducing disposal problem. Leaching characteristics are essential in understanding the environmental impact or toxicity, disposal and potential development of beneficial applications of WFS. This study aimed to presents micro-structural and metal analysis of fungal treated leachate obtained from concrete made with various percentages of WFS (0%, 10%, 15% and 20%).Metal concentrations of untreated and fungal treated leachate obtained from concrete made with WFS were analyzed for 15 metals including (Ba, Be, Cd, Cr, Co, Cu, Fe, Hg, Li, Mo, Mg, Mn, Ni and Zn) by using ICP-MS and compared with world Health organization (WHO) standard limits and ground water quality standards (GWQSs). Metal analysis indicates that WFS contribute to the concentration of leachable metals in concrete containing WFS. Results show the reduction in the metal concentration in leachate obtained from fungal treated concrete. In fungus (Aspergillus niger) treated WFS (10%) containing concrete, the metal concentration in Cd, Cr, Fe, Mo, Mn, Ni and Pb were reduced to significant levels. Micro-structural analysis confirms the improvement of concrete by inclusion of fungal treated WFS in concrete due to the formation of calcium rich biomineral in the pores of concrete.