A study has been made of the petrological characteristics of soft limestones, mainly from Jamaica, by microscopical examination of thin sections cut from specimens impregnated with dyed resin to strengthen the material and delineate the voids. Consideration of the relation between the petrological nature of the limestones and their engineering properties as indicated by laboratory tests has shown that the proportion of voids has a marked two-fold influence on strength as measured by the ten-per-cent fines test; strength increases as void-content decreases and as the proportion of voids filled by calcitic cement increases. The voids are themselves affected by the type and proportion of fossils present. The turbidity, which is a measure of the fine material, correlates well with abrasion, polished stone, specific gravity and water absorption values. In general, a higher degree of correlation between petrological and engineering properties occurs for the soft limestones examined than for the harder roadstones of the United Kingdom. It is considered that petrological examination could usefully be extended to other soft limestones to improve understanding of their engineering behaviour and to aid in selecting the most suitable roadstone in a range of soft limestones. (Author/publisher)
Abstract