Use of banana leaf ash as partial replacement of Portland cement in eco-friendly concretes

Abstract

• The BLA presented pozzolanic activity like other agroindustrial ashes. • Eco-friendly concretes with BLA increased compressive strength by 18 % at 90 days. • Performance and CII analysis indicated that BLA-10 is the best mix proportion. • SEM indicated that BLA-10 exhibits higher densification and lower voids. • TGA indicated that BLA can react with Ca(OH)2 and produce additional C–S–H. Currently, supplementary cementitious materials (SCMs) exist in the construction industry, including non-traditional materials such as banana leaf ash (BLA). The use of these materials drives the demand for a built environment with a smaller carbon footprint, reduction of pollutant gas emissions and agroindustrial waste generation. Thus, the research aims to investigate the use of BLA as a partial replacement for Portland cement (PC) in eco-friendly concretes. For this purpose, concretes were produced with replacement of PC by BLA at levels of 0, 5, 10 and 15% in relation to the weight of the binder, analyzing their physical (consistency, bulk density, dry density and water absorption), mechanical (compressive strength) and microstructural (SEM and TGA) behavior. The findings indicated that the concretes with BLA obtained improvements in the physical and mechanical properties with the increase of the substitution content up to 10%. Microstructural analyses indicated that the BLA can react with Ca(OH) 2 released during cement hydration and produce additional C–S–H, showing the pozzolanic potential of the residue. Therefore, the concrete with BLA-10 had significant improvements in its performance and properties investigated, becoming an environmentally friendly alternative for the production of the composite.