Analytical and Laser Scanning Techniques to Determine Shape Properties of Aggregates

Abstract

The fundamental shape attributes of aggregates used in pavements (i.e., form, angularity, and surface texture) have not been accurately quantified historically because of their irregular and nonideal shapes. This paper presents selected results from the use of a laser-based scanning technique to determine the form of aggregates employed in construction of pavements in South Africa. A three-dimensional (3-D) laser scanning system was used to examine aggregate materials from various sources, and the data were processed to reconstruct 3-D models of the aggregate particles. The models were further analyzed to determine the properties of the forms. Two analysis approaches based on physical properties of the aggregate and spherical harmonic analysis were employed to determine the form indices, and the results were compared. The indices based on the physical properties included (a) sphericity computed from the surface area and volume, (b) sphericity computed from three orthogonal dimensions, and (c) the flat-and-elongated ratio computed from the longest and shortest dimensions of an aggregate particle. Good correlations were observed between the form indices from the aggregate physical properties and the spherical harmonic form index. One conclusion of the research is that the laser scanning technique can be employed to quantify better the form properties of aggregate materials used in pavements.

Review of close-range three-dimensional laser scanning of geological hand samples

“…Angularity was calculated using mathematical morphology where the difference between a standard ellipsoid and the surface of the particles was determined. Komba et al (2013) and Anochie-Boateng et al (2013) tested laser scanning, specifically the Roland LPX-1200 scanner, as a new method to determine the "flakiness" of soil particles. Flakiness is defined as the ratio between the length, width, and thickness of a particle.…”

“…Certain minerals may be distinguished by studying their morphology, which can be accomplished by rotating a three-dimensional (3D) model to orientations that make the distinguishing features visible or apparent (De Paor, 2016). The morphology of sediment samples is used to assess the suitability of a sediment particle for engineering applications, such as railroad ballast (Komba et al 2013;Anochie-Boateng et al, 2013;Mvelase et al, 2016). Additional important information retrievable from this approach includes sediment particle transport history and paleoenvironment (Roussillon et al, 2009;Rossi and Graham, 2010;Hirmas et al, 2013).…”

Sphericity measures of sand grains

“…They noted poor correlation between these three indexes. Komba (Komba et al, 2013) used the same technique on six different gravelsized aggregates, acquiring data on 150 particles of each. They obtained material-dependent correlations between Ψ and a sum of low-order spherical harmonic coefficients.…”

Investigation of the Effects of the Type of Crusher on Coarse Aggregate Shape Properties Using the Three-Dimensional Laser Scanning Technique

“…Therefore, it is reliable to analyze the aggregate model to get an indication of the shape properties of the actual aggregate particle. Detailed procedure for the laser scanning of aggregates and processing of the scans data can be found in (Anochie-Boateng and Komba, 2010;Komba et al, 2013;Komba, 2013).…”