Granulometry of Two Marine Calcareous Sands

The morphology of two types of complex calcareous sand was investigated in this study. The materials were selected owing to their different geologic and biologic origins. Ledge Point is a bioclastic coastal sand, while Browse #1 is a hemipelagic sand. These two sands fall outside the range of common data sets used to correlate mechanical properties to particle shape parameters. Morphologic analysis of these calcareous sediments can aid with understanding the engineering behavior of calcareous soils. Moreover, sediments source tracing information could also be inferred from particle shape analysis. Two-dimensional Dynamic Image Analysis (DIA) was employed to capture five million and eight million particle images of each sand, respectively. A number of size parameters including diameter of equivalent projected circle (EQPC), Feret minimum, and Feret maximum diameter were efficiently obtained for each captured image using DIA, and used to investigate particle size distribution of these sediments. In addition, samples of over 800,000 particles were used to assess statistical distributions of various particle shape parameters including Aspect Ratio, Convexity, Sphericity, and Roundness-DIA (by volume). A Johnson family of distributions was found to provide a better fit to particle shape parameter distributions than the normal distribution for both sands. It is also shown that the Sphericity and Aspect Ratio are size independent, while Convexity and Roundness-DIA are correlated with particle size. Convexity is likely correlated with Sphericity for both calcareous sediments owing to their biogenic origin. Correlations of Roundness-DIA, Sphericity, Convexity, and Aspect Ratio and particle size are also observed but need more analysis.