Use of slags in concrete pavements and sub-bases

Industrial by-products have long been used in French road construction. Experience gained over the last twenty years with che extensive use of by-product gravel-sand stabilized with hydraulic binders as a sub-base material, as well as the results of highway engineering practice in neighbouring countries like Germany and Belgi~prompted the LPC (Central Laboratory for Bridge and Highway Engineering) to examine the possibilities of utilizing these by-products in concrete roads. Cements with a high content of additives, such as clinker-slag cements (CLK), have been used in full scale trials both for lean concrete sub-bases and for concreee pavements, as are reported in this paper. The resules of tests with concrete in which part of the cemene was replaced by finely ground slag or in which part of the natural sand was replaced by crushed slag sand are described and discussed, particularly with reference eo the erodability of the sub-base concrete. With additions of ground slag, it is possible to obtain favourable mechanical properties while significantly improving the competitiveness of concrete roads.