Effect of self-curing admixture and nature of the sand on the mechanical and microstructural properties of concrete in hot climate condition

Hot climates predominate in many countries of the world. The average summer temperature in hot and desert areas is around 40 to 50°C. Concreting in these regions creates different difficulties in the fresh and hardened properties of the concretes due to the rapid loss of the mixing water by evaporation. In this study, the effects of hot climate and formulation parameters on the fresh and hardened properties of concrete in hot weather were investigated. Three types of sand (calcareous sand, silico-calcareous sand and siliceous sand), presence or not of the superplasticizer and the curing compound were used on fresh concrete surface. The hot weather concrete test parameters are the temperature of the dry materials and the water (50°C) at the time of mixing, thus the air velocity and humidity were set at 12 km/h and 10%, respectively. The properties tested were workability and compressive strength. in addition, the microstructural analysis of the concrete was examined by SEM and XRD. The results showed that the concrete containing calcareous sand revealed a higher compressive strength than the concrete with siliceous or silico-calcareous sands. However, a high fluidity was obtained by concrete based on siliceous or silico-calcareous sands. In hot weather, by using a curing compound and a superplasticizer, the compressive strength of concrete was increased especially for concrete with calcareous sand. This study helps concrete technologists determine the optimum formulation to achieve concrete with desired hot weather properties.