Concrete @ your Fingertips |
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Limestone fines to BS 7979, Specification for limestone fines for use with Portland cement is a fine powder obtained from the processing of limestone. Limestone fines can be added to Portland cement as an addition, either at the factory to create a composite cement (CEM II/A-L/LL) or at the batch plant (CIIA-L/LL) to form a combination cement. There is uncertainty over whether limestone fines should be classified as a Type I (nearly inert as a filler aggregate) or Type II addition (with pozzolanic or latent hydraulic properties, for example, materials like fly ash (fa) and ground granulated blastfurnace slag (ggbs)). Limestone is less reactive than either fa or ggbs, but research shows that it can have slight reactivity as well as beneficial physical effects conferred by virtue of its fine particle size. BS 8500, Concrete - Complementary British Standard to BS EN 206 permits the use of limestone fines, under broad notation IIA (typically 6-20% of the Portland cement) and just uses designation L, but then if combined with another silo addition then all needs to be established under BS 8500-2 Annex B/D*. * The standard does not define the responsibility to undertake this testing i.e. potentially the cement supplier if a ´CEM´ and the concrete supplier if ´C´.
TR74 Cementitious materials
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