The 3-parameter packing density model with the wedging effect incorporated

Abstract

A concrete mixture can be regarded as a pack of aggregate particles in a matrix of cement paste. Since the matrix of cement paste is more expensive and less strong and durable than the natural aggregate, maximizing the packing density of aggregate is generally considered a good strategy both to reduce costs and to get an optimized concrete mix in terms of performance. For the sake of concrete mix optimization, it is important to have a particle packing model that can accurately predict the packing density of multi-component particulate systems. For this purpose, the 3-parameter packing density model (3PPM) has been developed. It is a new particle packing model for packing density estimation of multi-component particulate systems, which is modified from the linear packing density model by incorporating the wedging effect. The wedging effect is a particle interaction effect other than the loosening and wall effects, which occurs, for example, when the fine particles are locked at the narrow gaps between the coarse particles. An experimental program of measuring the packing density of binary and ternary mixes of mono-sized spherical glass beads was launched. The model was calibrated from the experimental packing densities of binary mixes. Then, the theoretical packing densities predicted by 3PPM for ternary mixes were compared with the experimental packing densities. With the wedging effect incorporated, the authors believe that 3PPM gives an excellent alternative tool for concrete mix optimization.