Mechanical performance of bedding mortars made with olive biomass bottom ash

Abstract

Two waste streams result from biomass combustion for power generation: biomass fly ash (BFA), which is used as fertilizer in agriculture, and biomass bottom ash (BBA) currently with no practical applications and generally deposited in landfills.This study provides significant information about the mechanical behaviour of mortars made with BBA, and the influence of several variables on such behaviour, namely type of cement, cement content, BBA incorporation ratio, and material type replaced with BBA.Two mortar families were produced according to the type of cement applied (CEM-I and CEM-II). In each family, three volumetric replacement ratios of natural sand (NS) with BBA (0%, 10% and 20%) and three cement contents (515g/L, 485g/L and 450g/L) were used. Mortars with replacement of cement with BBA (10% and 20% in cement volume) were also produced.Four mechanical properties were analysed: porosity, density, flexural strength and compressive strength. Strength was analysed at different ages to assess its evolution over time.There was a declining trend with the application of BBA for all properties analysed. Different behaviours were observed depending on the type of cement used or the material type replaced with BBA. Furthermore, there is an influence of porosity and density on strength due to the high absorption of BBA, allowing establishing meaningful relationships between the properties analysed.This paper proves the viability of bedding mortars with BBA depending on the cement type and content and the BBA incorporation ratio.