POTENSI SINERGIS ABU CANGKANG KELAPA SAWIT (POFA) DAN ABU SEKAM PADI (ASP) SEBAGAI SUPPLEMENTARY CEMENTITIOUS MATERIALS PADA BETON RAMAH LINGKUNGAN

Abstract

Palm oil and rice production constitute the two largest agro-industrial pillars of South Kalimantan Province, yet their combustion by products Palm Oil Fuel Ash (POFA) from crude palm oil (CPO) boilers and Rice Husk Ash (RHA) from rice mills remain largely unutilized waste streams posing environmental hazards. This systematic literature review analyzes the synergistic potential of POFA and RHA as Supplementary Cementitious Materials (SCMs) in green concrete formulation, examining physico-chemical characteristics, secondary hydration mechanisms, mechanical performance, durability, and CO₂ emission reduction implications. Synthesis of 32 Scopus-indexed studies (2009–2026) reveals: (1) POFA contains 56–65% SiO₂ with slow-stable reaction kinetics, optimal at 15–20% substitution; (2) RHA contains 85–95% amorphous SiO₂ with high reactivity, optimal at 10–15%; and (3) a binary blend of 10% POFA + 10% RHA enhances 56-day compressive strength by 15.0% and splitting tensile strength by 22.8% versus control, while reducing porosity by 19.7% and rapid chloride ion penetration (RCPT) by 55–58%. The synergistic effect operates through two complementary mechanisms: layered pore densification (POFA filling mesopores, RHA filling micropores) and differential pozzolan kinetics (RHA accelerates early Ca(OH)₂ consumption; POFA prolongs long-term C–S–H formation). Each 20% OPC replacement saves approximately 160–180 kg CO₂ per tonne of binder.