Effect of incorporating biomass bottom ash and construction and demolition waste powder on the physical-mechanical properties and micro-structure of ternary-blended mortars

Abstract

Biomass bottom ash (BBA) and construction and demolition waste (CDW) are two waste types whose recycling requires immediate actions due to the high quantities in which they are generated worldwide. Since the cement industry is currently facing a real challenge on a global scale due to the environmental cost implicit in cement production, the objective of this study was to evaluate the possibility of reusing those wastes as an addition in ternary-blended eco-cements with a lower impact than common cements. To achieve this, the chemical, physical, mechanical and micro-structural characterisation of the pastes and mortars manufactured with substitution percentages of 10–40% and 1:1 ratio was carried out. The results showed that the mixture of biomass bottom ash and construction and demolition waste powder in the same proportion had the capacity to fix lime and that the new ternary-blended eco-cements made with 20%, 30% and 40% substitution can be classified as CEM IV/A or CEM IV/B pozzolanic cements pursuant to the EN 197–1 standard. All of the new eco-cements also met the regulatory requirements for initial setting time and soundness, with no workability problems recorded. Finally, the mortars made with cement substitutions up to 20% developed similar or greater compressive strength and presented lower porosity at a later age than the reference mortar, making them suitable for use in construction.