Development of Simple and Structured Model for Packing-Density Assessment of Gap-Graded Coarse Aggregates in Concrete

Aggregate particle size distributions, shape characteristics, proportions and compaction level collectively influence packing density and, in turn, concrete properties. However, the available packing density prediction models either do not account for aggregate shape characteristics or if they do, the calculations are complicated and applicable only for well-graded aggregate systems. Hence, there is a need for the development of a simple and systematic model to predict aggregate packing density. The Aggregate Image Measurement System (AIMS) was used to obtain the shape parameters of aggregates. Aggregate shape indices were developed to correlate binary (gap-graded) aggregates. A new simple and structured RNP (Ramakanta Nabodyuti Prakash) model is presented in this paper for the estimation of packing density of binary coarse aggregate combinations with the use of shape parameters. The model was developed using a discrete element method (DEM) simulation in EDEM and validated using the experimental results. In the final section of the study, the compressive strength of engineered gap-graded concrete was also evaluated to test the applicability of the model.