Leaching Behavior of Heavy Metals from Cement Pastes Containing Solid Wastes

The leaching behavior of heavy metals from the cement pastes containing solid wastes including fly ash (FA), or municipal solid waste incineration fly ash (MSWI), was investigated by means of the tank test. Effects of two kinds of curing conditions (standard curing and natural curing) and carbonation on the leaching characteristics of heavy metals were studied. The environmental assessment relating to the leaching of heavy metals was also discussed. Results indicate that the leached heavy metals are mostly produced at early age of 28d, and subsequently decrease sharply to be undetected. Specimens subjected to the standard curing exhibit the lower S64d leaching concentrations of heavy metals than those exposed to the natural curing. Specimens under carbonation show the highest S64d leaching concentrations of heavy metals, compared with those at the standard curing and the natural curing. The long-term exposure of cement concrete containing MSWI and FA to the water environment may lead to the Cr pollution and the Cd pollution, respectively.