Michael F. Petrou

Crushed limestone as an aggregate in concrete production: the Cyprus case

Abstract Limestones in Cyprus are mainly quarried for the production of coarse and fine aggregates to be used in concrete. The objective of this paper is to examine the properties of crushed limestone aggregates. The petrographical and physico-mechanical properties of these aggregates are described and their suitability for concrete production is examined. The coarse crushed limestone aggregates from Cyprus have water absorption values exceeding 3.3%, which is considered high for concrete applications. Their abrasion resistance (Los Angeles) values are consistently above 23%, while their weathering coefficients generally range between 10 and 30%. The fine crushed limestone aggregates show significantly lower water absorption values (less than 2.2%) and higher weathering coefficients (above 35%) than the coarse aggregates. The weathering coefficient of crushed limestone aggregates increases with a decrease in the fraction size up to 5 mm, after which it remains fairly constant. The physico-mechanical properties of crushed limestone aggregates are distinctly variable irrespective of the fact that they belong to the same geological formation and show relatively similar petrography.

Towards more sustainable and environmentally-friendly concretes: The use of silica fume

Concrete is the most widely used construction material. At the same time, however, the concrete industry is a major CO2 emitter thus contributing towards global warming. While enhanced efficiency in the production of concrete is not likely to dramatically reduce the CO2 emissions, cement replacement by a supplementary material or mineral additive, such as silica fume, which is not associated with CO2 emission, can substantially reduce the aforementioned problem. The present work discusses the benefits of incorporating mineral additives in concrete and shows that these additives can improve both the mechanical and physical properties of the end-product, and hence its durability, albeit with a reduction in cement content.