| dc.description.abstract | The results indicates that during fly ash melting at 1250 and1400℃, more than 90% Cd, 40% Zn, and less than 20% other target metals (Pb, Cu,Cu) moved to the melting fly ash and exhaust gas. The TCLP leaching concentrations for the target metals (Cd, Pb, Zn, Cr, Cu) were all well below the regulatory thresholds. The unconfined compressive strength (UCS) of the SBC paste using 1400℃-slag was slightly greater than that using 1250℃-slag, showing that temperature effects in the tested range were insignificant. The early UCS of SBCP decreased with increasing replacement ratio and water/cement ratio, whereas the later UCS increased, showing the pozzolanic nature of the pulverized fly ash slag. The later UCS of SBPC with less than 20% replacement outperformed that of OPC, indicating the pozzolanic nature of pulverized slag to increase the later strength. However, the later strength decreased with increasing replacement ratio from 20% up to 40%. Moreover, the pore volume (<100 Angstrom) of the calcium silicate hydrates (C-S-H) gel formed during the hydration also indicated an increase with curing ages, suggesting that the active non-crystalline ions of slag such as Si and Al could react with Ca(OH)2 to form C-S-H gel, resulting in the filling in the pore space, thus increasing the later strength.
With respect to the effects of slag composition, the addition of CaO and Al2O3 promoted faster hydration and contributed to the early strength development of SBCP. However, the later strength decreased possible due to the efflorescence of Ca(OH)2 and micro-crack produced by the rapid transfer of aluminum compound. | en_US |