Pengaruh Kombinasi Fly Ash Lokal dan Silica Fume terhadap Kuat Lentur Beton untuk Perkerasan Jalan

This study analyzes the effect of combining local fly ash from PT Bukit Asam (PTBA) and PT Pupuk Sriwijaya (PUSRI) with silica fume addition on the flexural strength of concrete supporting the green pavement concept. Cement was substituted with 6% fly ash in PTBA, PUSRI, and 50:50 combination variations, along with 5% silica fume as an additive. Experimental testing used beam specimens (15×15×60 cm) evaluated at 7, 28, and 35 days according to SNI 4431:2011. Results show that concrete with 5% silica fume without fly ash achieved the highest flexural strength of 6.453 MPa at 35 days, while the 50:50 PTBA-PUSRI combination produced 6.173 MPa, higher than normal concrete (5.480 MPa). The higher pozzolanic reactivity of PUSRI fly ash contributed to the improved flexural performance of the blended mixture. The 50:50 PTBA-PUSRI fly ash combination with 5% silica fume is recommended as the optimal formulation for sustainable green road pavement applications.