Recycling of marine dredged materials coal fly ash and waste foundry sand as lightweight aggregates

Abstract

Nowadays sustainable environmental management of high quantities of marine dredged material (DM) together with other industrial wastes is a common problem across Turkey. The beneficial use/recovery of DM and wastes in the production of lightweight aggregate (LWA) instead of dumping at sea/disposal will provide substantial environmental savings in terms of circular economy. In this study the production of LWA by using marine DM coal fly ash and waste foundry sand were investigated. Three different mixtures of raw materials were granulated in pelletizing disc dried at 105 degrees C and sintered in muffle furnace at 1100 1150 1170 1180 and 1190 degrees C with 5-10 degrees C/min heating rates and 10-20 min sintering period. Sintered LWAs were analyzed in terms of physical mechanical microstructural mineralogical and leaching properties. LWA produced at 1190 degrees C sintering temperature 5 degrees C/min heating rate and 20 min sintering period resulted in better aggregate properties. Furthermore according to the leaching test resultsit is observed that the parameters of the eluate and original waste were lower than the Class III (inert waste) landfilling limit values due to the entrapment of those into the silicate matrix in sintering processthus causing no environmental risk to be used at construction sector.