Coupled effect of fine mortar and granular skeleton characteristics on dynamic stability of self-consolidating concrete as a diphasic material

Abstract

Dynamic segregation of 30 self-consolidating concrete (SCC) mixtures proportioned with low and normal binder contents was evaluated using T-Box set-up. SCC was considered as a diphasic suspension of coarse particles (>1.25 mm) in Bingham fine mortars (<1.25 mm). The investigated fine mortar mixtures were characterized in terms of workability and visco-elastoplastic properties. The dynamic segregation of the investigated SCC mixtures was found in good agreement with the flow properties of their corresponding fine mortars, including mini-slump flow, yield stress, plastic viscosity, critical strain, storage, and loss moduli values, as well as the relative solid-packing fraction (φ/φmax) of coarser portion of granular skeleton (>1.25 mm). Optimizing the paste volume and φ/φmax of coarse aggregate, rather than adjusting the water-to-binder ratio and high-range water-reducer dosage, was shown to be more effective in enhancing the dynamic stability of SCC. Furthermore, higher dynamic segregation of coarser particles was observed due to shear-induced changes in grading of granular skeletons. Trade-offs between the flowability, passing ability, static, and dynamic stability characteristics of the investigated SCC mixtures were established. Accordingly, a new comprehensive workability-based classification was proposed. According to the proposed approach, four normal- and one low-binder SCC mixtures with high stability and medium-to-high filling ability properties were identified.