This research investigates the microstructural and macrostructural effects of incorporating EAFD as a partial cement replacement in mortar mixtures and analyzes their behavior in both the fresh and hardened states. Standardized 50-mm mortar cubes were prepared with cement replacement percentages (0–30% by weight) and subjected to physical, mechanical, and petrographic characterizations. To evaluate the physical and mechanical properties, fluidity in the fresh state and compressive strength in the hardened state were measured. Compared to the control sample, mixture fluidity remained nearly unchanged at 5% substitution and decreased by only 10% at 10% replacement. Compressive strength results demonstrated that replacing up to 10% of cement with EAFD is highly viable for non-structural applications. However, higher substitution rates (15%, 20%, and 30%) resulted in a performance reduction of more than 15%. Petrographic characterization was conducted on samples with 0%, 10%, 20%, and 30% replacement, using fragments and thin sections after compression failure. Optical and scanning electron microscopy (SEM) were used to map interstitial compositions, compare crystalline phases, and analyze texture, mineral phases, and interactions among the paste, aggregate, and voids. Microstructural analysis revealed that increased EAFD content correlated with diminished adhesion between the aggregate and the paste. Furthermore, biotite grains tended to fail along foliation directions, with paste entering the open planes. Ultimately, this study confirms the feasibility of utilizing EAFD in non-structural cement mortars, offering a pathway to reduce environmental impacts, lower cement consumption, and advance Sustainable Development Goals (SDGs).
Herrera et al. (Tue,) studied this question.