Investigation of the ideal mixing ratio and steel fiber additive in ultra high performance concrete (Uhpc)

Abstract

Ultra high performance concrete (UHPC) generally has low workability due to the fact that it is a material with low water/cement (w/c) ratio and contains fiber in it. Therefore, adding a superplasticizer (SP) in its production may be a solution, so that it can self-compress, but there may be an overdosing problem. This research, conducted in two stages to determine ideal UPHC mixture, consisted of the first stage involving the determination of the sand/binder (s/b) ratio and the two stages, which included the determination of the ideal steel fiber ratio. To achieve ultra-high performance, the w/c ratio was reduced to 0.2 and the steel fiber was increased to a maximum of 2%. The fresh and hardened properties of UPHC were examined, for better workability their flow diameters and also compressive strengths, flexural strengths, densities, water absorption rates, total voids were determined in UPHC mixtures. It has been determined that the maximum strength can reach about 110 MPa without steel fiber reinforcement, but 130-140 MPa strengths can be achieved if up to 2% steel fiber is added to the mixtures. It has been found that the strength of the UHPC is related to the s/b ratio and the fiber volume used and that the UHPCs can be obtained when the ideal ratios are taken into account.