Performance Evaluation of Developed Concrete through Long Term Leaching, Durability and TCLP

Abstract

Solidification/Stabilization is a common practice for the treatment of hazardous waste containing heavy metals before it is disposed of in a secure landfill or for reuse. In order to evaluate the stability of the solidified waste for utilization, EPA Solids Water Leaching Test (SWLT) 846-1311, long term durability and leaching (NEN 7345) methods were used. Weight loss from the freeze/thaw (FT) durability test ranged from 0.37 - 0.98% and heat- thaw (HT) durability test ranged from 0.28 - 0.42% after 4 cycles. The obtained values were less as compared to the 30% weight loss standard. Ll and L2 concrete samples were soiled during Ff & HT durability test. Iron Leaching was found less than other metals (Cu, Zn) due to formation of high iron complex. Ff was found to be more deteriorating as compared to HT. During diffusion test conductivity increased with the increase in the waste content in the mix design and higher for the extractions with longer contact period. Diffusion was obtained in the start path and middle path of all concrete samples. The leaching mechanism showed low leaching of copper and zinc as compared to iron. Iron release decreased with increase in waste/binder ratio. Chromium, nickel and manganese were completely stabilized in concrete matrix. The order of fixation of metals on the basis of their leachability index are Fe>Zn>Cu>Cr>Ni>Mn. The TCLP result proved that the developed materials were in the permissible limits of Hazardous Waste (Management & Handling) Rules.