Study on Improving the Properties of Alkali-Activated Materials by Using Corncob Ash

Corncob ash (CA), a byproduct of agricultural production, is a potential resource for biomaterial applications. This study investigated the changes in the mechanical properties, linear shrinkage, setting time and microstructure of alkali-activated materials after incorporating CA. Results indicated that blending CA with alkali-activated mortar (AAM) substantially enhanced its mechanical and shrinkage properties. The 28 d compressive and flexural strengths reached 60.1 and 8.9 MPa, respectively. Furthermore, the AAM exhibited a 14.5% and 13.4% reduction in shrinkage at 56 and 60 d, respectively, compared with the control group. With a 4.0% CA content, the initial and final setting times of the blended alkali-activated cement with a 3.0% alkali concentration were 138 and 221 min, respectively. Mechanical strength and linear shrinkage of the AAM increased with higher alkali activator concentrations, whereas the setting time of the alkali-activated cement decreased. CA, characterized by a porous structure, does not generate new substances within the alkali-activated cementitious system and its inherent carbon sequestration capacity can substantially reduce carbon emissions associated with AAM. This study provides a preliminary investigation into the effects of CA on alkali-activated materials, contributing to the advancement of research and applications of these materials and biomaterials in green building construction.