In order to study the behaviour of a roller compacted concrete (RCC) reinforced with polypropylene fiber, six types of RCC were made with different content of fibers (0, 0.5, 1, 1.5, 2 and 2.5 Kg/m 3 ). The physical parameters are the density, the workability, the shrinkage and the water absorption. For the mechanical parameters; the performances such as the compressive strength and the tensile strength (3 point bending and splitting) has been studied.The results show that the RCC reinforced with fibers present the better performances in terms of strength and physical behaviour. The results obtained show the positive effect of the polypropylene fiber addition on the mechanical strength, which increases about 23% for the mixture with 1 Kg/m 3 . For the physical properties, there is a decrease in the density and workability and an improvement in the water absorption proportional with the addition of polypropylene fiber. In addition, we conclude the positive effect of polypropylene fiber on the kinetics and development of the shrinkage. In this study, the best physical and mechanical performance was being observed in the mixture with 1 Kg/m 3 of polypropylene.

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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.