An Inexpensive Foldscopic Approach for Quantitative Evaluation of the Shape of Sand Particles

Shape is a fundamental key property of any object and an important physical attribute that remains ignored, although its importance has been accepted for quite some time and is not accounted for in standard soil classification guidelines. One of the reasons for this could be the lack of inexpensive microscopic instruments or image scanners in most laboratories. This study quantifies particle shape characteristics using a cost-effective foldscope approach. Four different types of sand were used in this study and results were compared against scanning electron microscopy (SEM) measurements. In addition, the effect of the number of particles and resolution on the analysis is discussed. It was found that the foldscope-based approach yielded consistent results with SEM in measuring the aspect ratio and roundness parameter (except circularity). The variation between the two approaches was found to be less than 5% for both aspect ratio and roundness; however, a significant difference was observed in the case of circularity (more than 50%) due to the influence of resolution