Optimizing compressive strength of concrete incorporating metakaolin and palm oil fuel ash

Abstract Metakaolin (MK) and palm oil fuel ash (POFA) were utilized in high strength concrete (HSC) as a partial substitutes for cement, which is responsible for high CO 2 emissions. The combined effect of (5-15%) MK and (20-40%) POFA on the compressive strength of HSC was thoroughly examined using response surface methodology (RSM). In particular, central composite design (CCD) was adopted to optimize the compressive strength of ternary blended concrete at 7 and 28 days. Through analysis of variance (ANOVA), the developed models demonstrated statistical significance, as evidenced by a level of significance < 0.05 and a high coefficient of determination (R 2 ). The findings suggested that an optimal mixture, incorporating 12-15% MK and 20-27% POFA, could enhance the strength of concrete, meeting the criteria for optimization. The greatest improvement of HSC was achieved with a combination of 14.89% MK and 20.48% POFA. The enhancement of concrete strength was attributed to the pozzolanic reaction and the dense matrix resulting from the synergistic effect of MK and POFA.