STAINLESS STEEL SLAG AS AGGREGATE IN HOT-MIX ASPHALT PAVEMENTS

摘要

This contribution describes the Belgian experience with the use of stainless steel slag as aggregate in hot-mix asphalt for road construction. Slag from stainless steel production is a stony material with good mechanical properties. Earlier research has shown that it can be used as aggregate in construction blocks and in road construction. However, because of the rather high concentrations and leachability of the heavy metals chromium and nickel and also of fluorine, Flemish environmental legislation makes it mandatory to bind such slag with a stabilizing agent (like bitumen) in order to bring the leaching of those elements down to an acceptable level. Laboratory studies have demonstrated the capability of this slag to be used as aggregate in a conventional type of hot-mix asphalt. After breaking and sieving, the slag is available in two sizes: 0/7 mm and 7/20 mm. Both sizes are used as an aggregate for the mixture, with an addition of natural sand. Attention should be paid to some special characteristics of the slag - like higher density, porosity and surface roughness, which result in higher bitumen consumption by the asphalt mixture. Trial sections of road pavements with stainless steel slag have shown good results for the mechanical stability of the mixture and for resistance to rutting and polishing. They demonstrate the possibilities for successful recycling of stainless steel slag as aggregate in hot-mix asphalt mixtures for road construction.