Estimation of aggregate gradation from partial gradation information obtained by multiple imaging equipment

Abstract

The aggregate gradation is an important consideration in bound or unbound mixes, as it influences the engineering properties of the mixes (both during and after construction). In recent times, effort is being made to employ imaging methods to predict the gradation of aggregates in the mix. This approach involves acquisition of two- (or three-) dimensional image of the aggregates distributed within the mix and subsequent image analysis. The size of the aggregates for a given mix typically varies by several orders of magnitude, and thus, it may not be possible to capture the entire size-range of the aggregates using a single imaging equipment. Different imaging equipment may be effective for different size ranges, and hence would individually provide partial information on the size distribution. In the present study, a simple formulation is developed (for two-dimensional images) that can be utilised to collate the partial information (obtained by various imaging equipment) to generate the overall aggregate size distribution of a given mix. To illustrate the formulation developed, two-dimensional images of asphalt mix acquired by scanner, camera and scanning electron microscope are utilised so as to predict the overall aggregate gradation originally used in the asphalt mix.

Keywords:

• Asphalt mix
• aggregate gradation
• imaging equipment
• image analysis

Acknowledgements

The authors sincerely thank Mr. Abhijit Swain, a PhD student in the Department of Civil Engineering, IIT Kanpur, for his help in capturing the camera images used in the analysis of the present paper.

Disclosure statement

No potential conflict of interest was reported by the authors.