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Hydration, Shrinkages and Mechanical Properties of Ultra High Performance Concrete Containing Blast Furnace Slag and Algerian Dune Sand

The new requirements for strength and durability have led to the development of Ultra High Performance concrete (UHPC) with outstanding mechanical properties and durability. However, the application of this type of concrete is exceptional, because of the high dosage of cement and the incorporation of expensive materials, such as silica fume (SF) whose dosage can reach 30% by weight of cement. This type of concrete is formulated on two bases: A fine granular skeleton (max diameter 630μm) and high cementitious materials content. The search for local materials to exploit them in the formulation of UHPC is the current trend. It is therefore necessary to control their effect on the behavior and evolution of cement hydration.The objective of this study is to highlight the influence of blast furnace (BFS) on hydration kinetics, linear endogenous shrinkage and chemical shrinkage at very early age (before 72h), drying shrinkage after hardening, as well as, the evolution of mechanical compressive strengths as a function of time. In addition, the exploitation of dune sand in the granular skeleton is an alternative to reduce the crushing energy and avoid microcracks possibly induced.The analysis of the results showed the interest of the use of the dune sand and the partial substitution of the cement by the BFS on the properties of the UHPCs in the fresh state and in the hardened state.In addition to the high performance achieved by UHPCs, their use, in Algeria, will meet both economic and ecological requirements given the abundance of very fine dune sand (southern Algeria) and complex blast furnace BFS of EL-Hadjar (Eastern Algeria).