A study on durability properties of high-performance concretes incorporating high replacement levels of slag

This paper presents an experimental study of combined effects of curing method and high replacement levels of blast furnace slag on the mechanical and durability properties of high performance concrete. Two different curing methods were simulated as follows: wet cured (in water) and air cured (at 20 degrees C and 65% RH). The concretes with slag were produced by partial substitution of cement with slag at varying amounts of 50-80%. The water to cementitious material ratio was maintained at 0.40 for all mixes. Properties that include compressive and splitting tensile strengths, water absorption by total immersion and by capillary rise, chloride penetration, and resistance of concrete against damage due to corrosion of the embedded reinforcement were measured at different ages up to 90 days. It was found that the incorporation of slag at 50% and above-replacement levels caused a reduction in strength, especially for the early age of air cured specimens. However, the strength increases with the presence of slag up to 60% replacement for the 90 day wet cured specimens. Test results also indicated that curing condition and replacement level had significant effects on the durability characteristics; in particular the most prominent effects were observed on slag blended cement concrete, which performed extremely well when the amount of slag used in the mixture increased up to 80%.