Mechanical Properties and Failure Pattern of Fly Ash-Based Geopolymer Mortar with Sugarcane Bagasse Ash and PVA Fiber

Abstract

Fly ash-based geopolymer mortar offers a promising low-carbon alternative to Portland cement, yet the combined influence of sugarcane bagasse ash (SCBA) chemical composition and polyvinyl alcohol (PVA) fiber reinforcement on mechanical properties and failure behavior remains insufficiently understood.This study investigates fly ash-based geopolymer mortar incorporating raw SCBA at substitution levels of 0%, 10%, 20%, and 30% by weight of fly ash, combined with 0.6% PVA fiber by volume, activated with 10M NaOH and sodium silicate solution under ambient curing.Chemical composition was characterized using X-ray fluorescence (XRF) and X-ray diffraction (XRD).Mechanical testing at 28 days covered compressive strength and splitting tensile strength, accompanied by crack pattern observation.XRF confirmed fly ash as Class C (SiO₂+Al₂O₃+Fe₂O₃ = 55.7%,CaO = 26.2%)and SCBA as Class N with a loss on ignition of 14.8%, exceeding the ASTM C618 limit.XRD identified quartz (67.3%), cristobalite II (26.6%), and hematite (6.1%) as dominant SCBA phases.The 10% SCBA substitution achieved the highest compressive strength of 21.07 MPa, satisfying the ASTM C270 Type M minimum of 17.2 MPa.Higher SCBA contents progressively reduced mechanical performance, attributed to elevated LOI and crystalline phase dominance that limited geopolymerization reactivity.Crack patterns shifted from distributed corner cracking at 10% SCBA to wider diagonal shear cracks with increased spalling at 30%, reflecting progressive loss of matrix cohesion.These findings establish compositional thresholds for raw SCBA in PVA fiber-reinforced fly ash geopolymer mortar, guiding low-carbon structural mortar design.

Access to Document

Other files and links

• Link to publication in Scopus
• Open Access Version Available

Fingerprint