Optimum superplasticiser dosage and aggregate proportions for SCC

Abstract

An experimental study has been carried out to investigate the effect of superplasticiser dosage on the performance of self-consolidating concrete (SCC). Seven concrete mixes with water/cement (w/c) ratios ranging from 0·35 to 0·45 and fine/total (F/T) aggregate ratios ranging from 0·40 to 0·60 were designed and 42 batches of concrete containing different dosages of superplasticiser were produced. The workability, passing and filling abilities, and segregation stability of the concrete produced were measured using the slump flow, U-box, and sieve segregation tests respectively. For each concrete mix designed, the superplasticiser dosages for maximum slump flow without segregation and maximum filling height were determined. It was found that the maximum performance of the concrete mix and the respective required superplasticiser dosage are dependent on the w/c and F/T aggregate ratios. In general, increasing the F/T aggregate ratio would improve the maximum performance but would also increase the superplasticiser dosage needed. Lastly, the robustness of each concrete mix was evaluated quantitatively as the range of superplasticiser dosage or slump flow satisfying all requirements for SCC. Based on these results, the optimum superplasticiser dosage for maximum robustness of each concrete mix was determined.