Implications of uncompacted packing density of aggregates in self-compacting concrete mix proportioning

Abstract

This study forms part of ongoing research on sandwich panels by the authors’ research team at CSIR-SERC, India, where there is a demand for self-compacting concrete with a limit on aggregate of size up to 10 mm, and with approximate cube strength and slump flow in the ranges 45–50 MPa and 600–700 mm, respectively. These requirements are achieved using a packing density concept for aggregates. In self-compacting concrete, when the concrete has not been compacted or vibrated during and after pouring, the uncompacted packing density of aggregates determines most of the aggregate-related attributes of the concrete. To obtain the uncompacted packing density of the aggregates, existing theoretical models for binary combination of aggregate are extended to ternary combination and the model with least deviation from the experimental procedure is chosen for the mix proportioning of aggregates in the self-compacting concrete. The extended Toufar model is identified as giving better uncompacted packing density in agreement with the experimental study, and is used for the proposed mix proportion. In the proposed mix proportioning method, slump flow is achieved without compromising the cube strength by optimising the aggregate volume, binder combination and superplasticiser dosage.