Marl as a supplementary material to alkali-activated blended cements

Abstract

© 2019, © 2019 Informa UK Limited, trading as Taylor & Francis Group. The increasing need of raw materials is one of the drivers for further development of inorganic binders, including alkali-activated cements. This research focuses on the study of the potential suitability of raw and calcined marl with a high calcite/aluminosilicates ratio as a supplementary material for alkali-activated blended systems using alkali-activated salg cement as an example. Marl calcined at 800 °C was found to be a more promising supplementary material for alkali-activated blended cements compared to raw marl. The thermal treatment at 800 °C results in the partial amorphization; formation of reactive Si, Al, and Ca due to the dehydroxylation of clay minerals and decarbonation of calcite. These provide the marl with the capability to form aluminosilicate hydrate gels and contribute to the mechanical characteristics of hardened activated mixed pastes. The hardened blended ground granulated blast furnace slag/calcined marl systems activated by hydrous sodium silicate and cured at room temperature had 28-day compressive strength of 27.5–40 MPa depending on the ratio of the slag/calcined marl. XRD, TG/DSC, FTIR, optical microscopy, and SEM were used to investigate the reaction products, as well as the microstructure of the activated blended pastes.