Utilisation of aged and unaged basic oxygen furnace steel slag aggregates in pavement quality concrete

The study presented in the paper evaluated the properties of pavement quality concrete (PQC) containing coarse aggregates made from aged and unaged basic oxygen furnace (BOF) slag. Workability, air content, strength, drying shrinkage, expansion, abrasion resistance and expansive potential of PQC were evaluated. Air content and workability of fresh slag concrete increased marginally. Compressive and flexural strength of the concrete containing aggregates of aged and unaged slag was observed to be less than the strength of normal concrete. The reduction in strength of concrete containing aged slag aggregates was more as compared to the concrete containing unaged slag aggregates due to the presence of a dusty coating around the aged aggregates. The drying shrinkage of the concrete increased with the content of steel slag aggregates. The abrasion resistance of the slag concrete was found to be better than the abrasion resistance of conventional concrete. Deterioration of slag concrete was not observed due to normal water curing up to 90 days. However, accelerated aging of concrete in water at 70°C resulted in the localised cracking and eruptions due to expansion. The study showed that, aged as well as unaged slag aggregates may be used for the preparation of concrete mixtures of required properties for road construction.