Sensitivity of compressive strength of HSC to hot-dry climate, curing regimes, and additives

Seventy 152 mm (6 in.) concrete cubes and fifteen 152 x 305 mn (6 x 12 in.) cylinders of high-strength concrete were cast and tested. The influence of different curing methods on reducing the deleterious impact of adverse climatic conditions on the compressive strength was evaluated. Other variables considered in the study were the shape of the specimens, addition of silica fume, type of curing compound curing period, and replacement of superplasticizer by retardant and plasticizer. It was found that, for concrete tested 28 days after casting, treatment with resin compound applied to the exposed surface of the specimen provided better protection to concrete than intermittent spraying of water However intermittent spraying of water with and without burlap covering also provided arl acceptable means of protecting concrete against adverse climatic conditions. It was also found that adding 10 percent of silica fume to the concrete mix may increase the compressive strength of the concrete by 25 percent without influencing its sensitivity to hot weather effects. Conversely, replacing superplasticizer by an equivalent quantity of retardant and plasticizer (based on equal concrete slump) reduced the compressive strength by about 10 percent, bur the concrete became less sensitive to adverse climatic conditions. Furthermore, Sor concrete rested 90 days after casting it became visible that concrete cured by intermittent spraying of water with burlap covering had a higher compressive strength than that cured by water spraying with no burlap covering.