Influence of leachate composition on the leaching behaviour of concrete

In this work the leaching of heavy metals from concrete in contact with different leachates was investigated to quantify the influence of the leachate composition. Four different types of ground water, two synthetic waters as well as deionised water were selected and tank leaching tests were carried out using the standardised horizontal dynamic surface leaching test (DSLT). Four concrete mixtures with varying binder compositions and water/binder ratios were tested. The results show that the leachability of trace elements and heavy metals strongly depends on the water hardness respectively the calcium concentration and the availability of hydro carbonate in the leachate. The impact of these parameters is presented. It is pointed out, that the use of deionised water delivers overrated element releases and that by the use of ground water as leachate more realistic evaluations of the environmental compatibility of concrete are achievable.