The influence of containing supplementary cementitious materials on preparation and properties for UHPC

The preparation of ultra-high performance concrete usually required expensive materials and harsh curing conditions, which limited its application in engineering widely. It may be solved by adding supplementary cementitious materials (fly ash, ground granulated blast slag, silica fume and so on). This paper is dedicated to determining the optimal mix ratio of UHPC under common preparation methods and raw materials and under common maintenance conditions to expand the applications of UHPC. The influence of the ratio of water to binder, the ratio of sand to binder, the content of supplementary cementitious materials on UHPC slump spread, compressive strength of 7 days and 28 days, apparent density and tensile strength of 28 days were researched by orthogonal test. The results revealed that the method of semi-dry mixing could enhance the homogeneity of steel fiber and improve the rate of its utilization. When the replacement of cement achieved 50% by the supplementary cementitious materials, the performances of UHPC were still guaranteed and confirmed. When the ratio of sand to binder reached 1.1, the ratio of water to binder reached 0.17, ground granulated blast slag was 25%, fly ash was 10% and silica fume was 15%, its slump spread reached 580 mm, compressive strength and tensile strength reached 152.9 MPa and 14.2 MPa respectively in 28 days under natural curing conditions. Therefore, the UHPC with supplementary cementitious materials should be considered as one of the sustainable development and environmental protection materials.