Hot climate causes the concrete to loose its workability at a higher rate to the extent that placing the concrete may become difficult or impossible. Site engineers may be tempted to apply retempering, a controversial practice by which water is added to restore the original slump of the concrete before placing, to save some concrete batches. Previous investigations have focused on the effect of retempering on the compressive strength of concrete made with Ordinary Portland Cement (OPC) only and were inconclusive. This study was mainly carried out to investigate the effect of retempering on the compressive strength and some durability related properties, i. e. capillary absorption and porosity, of OPC, silica fume and fly ash concrete. Retempering of pozzolanic mixes lead to a loss in the compressive strength greater than that observed in the OPC counterpart, but the strength would still be greater than a comparable OPC mix with the same w/c ratio. However, the improvement in durability, expected from the inclusion of pozzolanic materials, may be diminished due to retempering.
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