The presence of platy sand-sized mica particles, even at small percentages by mass, may have a major impact on the engineering properties of a 'host" sand. For assessing the impact of mica content of a micaceous sand in the context of the associated engineering implications, it is important to distinguish between mica in the form of individual sand-sized particles versus mica as a mineral group. Mica as a mineral can be present across the full particle size range from sand-sized particles to silt-sized and clay-sized flakes. Mica as a mineral can also be found as part of lithic fragments from mica bearing rocks. Mineralogy testing often involves Xray Diffraction analysis (XRD) to quantitatively determine the mineral composition. In addition, Heavy Liquid Separation (HLS) and point counting based on microscopic images are other techniques used to determine the mica content. Based on learnings from an offshore wind farm project in Taiwan, this paper discusses the challenges of mica content determination focussing on the applicability of different measurement techniques.
Kee Kiat Tho, Nancy Chan, Anders H. Augustesen, Edward Molyneaux, Lone Krogh and An-Bin Huang
Keywords: micaceous sand, mica content, XRD analysis, point counting, microscopy
Publisher: DFI