Enrichment of Fine Mica Originating From Rock Aggregate Production and Its Influence on the Mechanical Properties of Bituminous Mixtures

Free mica grains in crushed rock aggregates

“…3). Considering the results from Miskovsky (2004), Lagerblad (2005 and the present study, it is assumed that the position (grain size fraction) and the height of the peak (content of free mica) depend on the rock's initial mineral composition and mean grain size thus indicating the importance of microstructural characteristics for the variation in free mica in crushed rock aggregates. Lagerblad also carried out SEM analysis on five samples for fractions <38 and 37-63 lm.…”

“…The three samples used in this study provide a somewhat sparse basis for reasoning, thus a review of some data in the literature on free mica in crushed rock aggregates for construction purposes was motivated. Miskovsky (2004), using a polarizing microscopy and the point-count method, showed a general increase in the amount of free mica for the finer fractions (<0.074, 0.074-0.25 and 0.25-2 mm), analysing five samples of granitoid rocks with varying mica content (5.6-33 vol.%; Fig. 6).…”

“…Microstructural comparison between the studies is not possible as no structural information is provided by Miskovsky (2004) except that the samples were granitoid rocks.…”

“…clay minerals and micas), implies a high risk of constructional deterioration. Hakim and Said (2003) and Miskovsky (2004) show a material deterioration of bituminous mixtures connected with an increase in the amount of micas in the fine fraction (<2 mm). A similar relationship has been described by Lagerblad (2005) for fine fractions used in concrete.…”

“…A similar relationship has been described by Lagerblad (2005) for fine fractions used in concrete. Miskovsky (2004) shows a general trend of increase in the amount of free mica when comparing narrow grain fractions, having analysed five samples of granitoid rocks with varying mica content. Whereas Lagerblad (2005) states that there is a steady increase in the amount of free mica with a peak for grain sizes between 0.125 and 0.25 mm, for smaller grains no enrichment was detected.…”