<![CDATA[The utilization of calcium carbide residue as a calcium-rich secondary binder offers a route to improve industrial-waste valorization in fly-ash geopolymer concrete. This study evaluates the fresh and mechanical performance of geopolymer concrete containing a 50:50 mass proportion of low-calcium fly ash and calcium carbide residue in the precursor fraction. The aggregate-to-binder ratio was 60:40, the precursor-to-alkaline-activator ratio was 70:30, and sodium hydroxide and sodium silicate were used at a 1:1 ratio. Cylindrical specimens (100 mm × 200 mm) were tested in compression at 7, 14, and 28 days, while splitting tensile strength was measured at 28 days. The mixture produced a slump-flow diameter of 555 mm, indicating high flowability despite its visually cohesive and sticky consistency. Average compressive strengths reached 13.81, 17.53, and 23.67 MPa at 7, 14, and 28 days, respectively, corresponding to a 71.4% increase from 7 to 28 days. The 28-day splitting tensile strength was 2.54 MPa, equivalent to 10.7% of the compressive strength. Compressive failure was dominated by longitudinal splitting with localized end spalling, whereas the splitting test produced a nearly straight diametral crack without massive aggregate loss. The findings demonstrate that a high-volume carbide-residue/fly-ash binder can develop structural-grade compressive strength under the adopted activation system.]]>
Copyrights © 2026
