The use of biomass to produce electric power and heat will intensify in the years to come, in pursuit of sustainable growth. Stockpiling the vast amounts of fly and bottom ash generated in that process wastes resources and has an adverse impact on the environment. The viability of bottom ash as a supplementary cementitious material in new eco-efficient cements is studied, including its effect on binder chemical, rheological, mechanical and microstructural properties. The findings show that these additions induce improvements in later age mechanical performance relative to conventional mortars. An ANOVA conducted to determine the impact of waste type, replacement ratio and curing time on compressive and flexural strength reveals that the latter two have a significant effect on mechanical properties. The new cements meet the requirements laid down in EN 197-1 for CEM II/A and CEM IV/A cements, making them apt for use in construction.

This research was funded by the Spanish Ministry of Economy and Competitiveness (BIA2015-65558-C3-1-2-3R and BIA2016-76643-C3-1-R) (MINECO/FEDER), as well as by the Government of Extremadura and the European Regional Development Fund (ERDF) under grant GR 18122 awarded to the MATERIA research group.

Peer reviewed