ENVIRONMENTAL COMPATIBILITY OF FLY ASH INCORPORTAED CONSTRUCTION MATERIALS

摘要

The leaching of heavy metals, such as Cr (total chromium and Cr~(6+)), Pb, Cd, Zn, Mn and so on, in fly ash cement mortars and cement-solidified fly ashes has been investigated by tank leaching and shaken extraction test methods; comparisons were made between the leachability of heavy metals under different pH conditions and of metals from specimens at different curing ages. In addition, a pH controlled shaken extraction test method was proposed. The results of this study mainly indicate that; (1) heavy metals do leach from the tested specimens; (2) compared with the tank leaching test, a shaken extraction test can extract more toxic heavy metals; (3) the leachability of some heavy metals is greatly dependent on leachant pH; and (4) increased leaching of both Cr and Cr~(6+)will occur when cement mortars have been carbonated.