Bituminous base courses for flexible pavements with steel slags

Abstract

The purpose of this research was to study the feasibility of incorporating steel slags into coarse bituminous mixtures. The objective was twofold: to reduce dependence on natural aggregates, and to provide a use for industrial by-products. The slags studied come from the manufacture of carbon steel in electric furnaces and are divided into two types: Electric Arc Furnace (EAF) slag and Ladle Furnace (LF) slag. The mixture designed is coarse bituminous concrete (AC22G), for base courses in flexible pavements. In a first phase, the physical characterization of the materials was carried out to check their suitability. In a second phase, three types of mixes were designed: a control mix (made with natural limestone aggregates), a mix where LF slag was introduced to replace the filler and the fine fraction (sand) of the mix; and finally, the feasibility of manufacturing a totally sustainable mix was analyzed, which would fully incorporate EAF slag as coarse aggregate and LF slag as fine aggregate and filler. In a third and final phase, the designed mixes were subjected to different mechanical, water sensitivity, and durability tests. The research demonstrated that the incorporation of EAF and LF steel slag as a substitute for natural aggregate in coarse bituminous mixtures is feasible, meeting regulatory requirements, improving sustainability in the construction industry, as well as reducing emissions, and contributing to climate change mitigation.