Feasibility of using clays from Southeast European deposits in limestone calcined clay cements

Abstract

Recently, the cement industry has faced new challenges in addition to the environmental constraints of the last decade. The decline in availability and current inconsistent prices of common supplementary cementitious materials (SCMs), such as by-products from the iron industry or coal-fired power plants, have opened the search for more reliable materials. Research on cements containing calcined clays now serve as a possible solution to the forementioned problems. Clays containing the mineral kaolinite in sufficient quantities, when calcined and mixed with limestone powder, produce hydration products that can improve the strength and durability of concrete. In addition, the production of limestone calcined clay is reported to be less CO2 intensive, but this eco-efficient solution is viable only if the materials are locally available. For this reason, this study investigates the possibility of using natural clays from the Southeast European region (SEE) as cement replacements. A systematic experimental study was conducted on 18 different clays from 13 different deposits to determine the physical and mineralogical composition of the raw clays, their reactivity and mortar strength. The results were then related to the environmental contributions they might have in comparison with ordinary Portland cement in concrete.