Research to develop the use of L.D._x000D_
slag as an aggregate in road construc- tion is described. The chemistry and mineralogy of L.D. slags are shown to be generally similar to S. Yorkshire arc furnace slags, which have been success- fully used for road construction for many years, although both free lime and iron contents were found to be higher._x000D_
Physical and mechanical properties are good but the slags' high density will result in lower "covering capacity"._x000D_
"Weathering" in stock piles is shown to significantly reduce free lime levels fairly rapidly although around 50 per cent of the mean "fresh free lime" content is still present even after two years treatment.