Enhanced imaging analysis of aggregates for road and railway applications

Abstract

The South African pavement community has shown a keen interest in the use of imaging techniques to characterize the morphological characteristics of aggregates used in road and railway construction. This interest arises from the need to overcome the limitations of the traditional methods currently employed to quantify the shapes of these materials. Recent advancements and the use of enhanced aggregate imaging techniques for quantifying the shapes of crushed stone and ferro slag materials from 10 sources across the country are presented in this paper. A wide range of railway track ballast and road aggregates were selected from various quarries and sources across different provinces for this study. As part of this research, an improved protocol was developed to standardize imaging acquisition and ensure the repeatability of shape property measurements, thereby providing meaningful results and facilitating data analysis. The imaging analysis conducted in this study, which involved close to 2000 aggregate particles, revealed valuable insights into the angularity, surface texture, and flat and elongated ratio properties of coarse aggregates. Preliminary specification limits for these shape properties have been established. This contribution represents an initial step toward supporting the South African road and railway industry in adopting advanced techniques for the selection of aggregate materials.