Influence of the fine aggregate particle packing effects on the paste rheological thresholds of self-compacting concrete

Abstract

The paste rheological threshold theory could guide the prediction of the self-compacting concrete (SCC) performance from the paste mini-slump flow test. The prediction process was simplified, but the prediction did not consider the influence that the fine aggregate caused enough, possibly leading to a wrong mix design when the fine aggregate changed. To solve this issue, this study focused on the effect of the fine aggregate particle packing effects on the paste threshold. Based on the 3-parameter particle packing model, a fine aggregate packing parameter that can describe the fine aggregate particle packing effects more accurately was proposed to replace the original one, which considered only the particle size. Thus, the threshold calculation formulas were modified. To verify the modification, a total of five series of paste and SCC tests with different material compositions were conducted. Based on the bilinear interpolation method, the self-compacting paste zones (SCP zone) were obtained by original and modified thresholds. Through the comparison of SCP and SCC zones, the prediction accuracy of the proposed modification was evaluated by a certain evaluation method. The overlap area and relative position of the self-compacting zones were evaluated by the relative accuracy index Δε and the modification accuracy index Δ|ε’-1|, respectively. Through the modification of the paste thresholds, the overlap area of the modified SCP and SCC zones changed little. But the relative position of the modified SCP zone was closer to the SCC zone than the original SCP zone. The modified SCP zone showed more accuracy in prediction summarily. The proposed modification embodied the influence that the fine aggregate packing properties caused, expanding the description of fine aggregate particle packing effects in the paste threshold theory.