Setting times are considered as identification boundary of fresh and hardened states of concrete. Initial setting time governs the transportation, casting, compacting and finishing processes and, on the other hand the final setting time governs the strength development of the concrete. In the present work, the effects of silica fume, fly ash and slag, as partial replacement for cement, in presence of superplasticiser on the setting times and strength development of different concrete mixtures were examined. The results showed that utilization of pozzolanic materials retarded the setting times of the mixtures. The more replacement contents led to increase of setting times. The results also indicated that silica fume enhanced both the early and later age strength. Fly ash increased the later stage strength but had a negative impact on the early age strength. Subsequently, the early age strength and final setting time relationships were expressed by the experimental equations.
