Monitoring the Tendency of Heavy Metals Leached from Cement Mortar

Abstract

This study presents the results of two leaching tests for cement mortars. Industrial sludge slag is employed as a fine aggregate to determine the mortar’s leaching tendency. The proportion of quartz sand replaced by slag in cement mortars was 0, 10, 20, 30, 40 and 50% (weight-to-weight ratio), and the cement mortars were cured for seven, 28, and 90 days. Toxicity characteristic leaching procedure (TCLP) and semidynamic leaching test (SDLT) methods were used to determine the leaching characteristics of both sludge slag and cement mortars. All the TCLP leaching rates were lower than 1%. TCLP leaching results reveal that the concentrations of slag and cement mortar were not significantly related to the replacement ratio, but declined as the curing period was increased. The results of the SDLT show that heavy metal concentrations in the long-term leachate increased with the replacement ratio, as expressed by the input amounts of heavy metals and the leaching period. The TCLP and SDLT leaching results comfortably satisfy the regulations, proving the safety and suitability of slag utilized as fine aggregate.