Design and evaluation of physical, mechanical and micro-structural properties of eco-friendly binary-blended mortars using biomass bottom ash or construction and demolition waste powder

Abstract

In recent decades, waste production from biomass-fuelled power plants, as well as from building and civil engineering works construction and demolition, has increased considerably. The possibility of recovering this waste type as supplementary cementitious material (SCM) in manufacturing cement is a strategic tool for achieving the objective of reducing CO2 emissions by at least 55% (“Fit for 55″ by 2030). In this research work, the feasibility of incorporating 5%, 10%, 15% and 20% biomass bottom ash (BBA) and mixed powder from construction and demolition waste (CDWm) in the design of new eco-friendly binary cements was evaluated. To achieve this, the chemical, physical and mineralogical characterisation of the wastes was carried out; as well as a physical, mechanical and micro-structural characterisation of the pastes and mortars manufactured. The results showed that the new cements with BBA or CDWm meet the regulatory requirements for initial setting time, soundness and resistance. The mortars made with BBA also developed greater compressive strength and presented lower porosity at a later age than the reference mortar and the mortars made with CDWm. Finally, the new binary cements made with 15% and 20% BBA meet the requirements set forth in EN 197-1 for CEM IV/A cements, making them suitable for use in construction.