Ultra-High Performance Concrete Mixes with Reduced Portland Cement Content
Keywords:Binder, Fly ash, GGBS, Mineral additions, UHPC
AbstractUltra-high performance concrete (UHPC) usually contains a very high proportion of ordinary Portland cement which requires a high amount of energy for its production. The present investigations aimed at systematically developing UHPC produced with supplementary cementitious materials to achieving strengths above 150 MPa at an age of 28 days under normal conditions or above 200 MPa with heat treatment. The cement was replaced with different amounts of ground granulated blast furnace slag and fly ash. The effect on the workability of fresh concrete and the evolution of compressive strength was investigated. A reduction in water and super plasticizer requirement was obtained with these materials. However, compressive strength decreases with the content of mineral additions. This loss could be partly compensated by increasing the fineness of the slag or fly ash. It was found that the type and dosage of superplasticizer have a significant effect on strength development. An appropriate choice of materials enabled the achievement of strengths above 200 MPa after heat treatment for concrete made with binders containing 25% Portland cement and 75% slag.