The potential leachability from natural road construction materials

Leaching characteristics are used for the evaluation of waste materials in road construction. Few leaching tests have been performed on natural rock materials which implies that there is a lack of data to be used in comparison with waste materials. In order to form a basis for comparison of the leachability, nine natural road construction materials in Sweden were investigated using the availability test NT ENVIR 003. The results show that the leachable amounts of heavy metals and sulphur generally are very small, but under oxidising conditions the solubility of sulphide bound elements increases notably. Vanadium and chromium are probably present as ionic substitutes for other elements in mineral lattices and show very low leachability. The leachable amounts of some heavy elements, e.g. zinc, nickel and copper are higher in the rock materials and gravels than in the blast furnace slags.