Nevy Sandra, Natalina Damanik, Muhammad Akbar Caronge, Mochamad Soleh
This study investigates the mechanical, electrochemical, and microstructural performance of concrete incorporating Class F fly ash (FA) as a partial cement replacement under chloride exposure, with a focus on identifying the optimal substitution level for enhanced durability. Four mixtures containing 0%, 15%, 30%, and 45% FA were evaluated through compressive and flexural strength tests, half-cell potential monitoring, and SEM analysis. Results show that FA incorporation significantly influences both strength development and corrosion behavior. The 15% FA mixture exhibited a positive effect, achieving 8–10% higher compressive strength and 3% higher flexural strength than the control at 90 days, while substitutions of 30% and 45% FA showed negative impacts on early-age strength due to reduced cement hydration. Electrochemical measurements revealed that the 15% FA mix maintained half-cell potentials between − 265 and − 290 mV, indicating delayed corrosion initiation, whereas the control and 45% FA mixtures reached − 368 mV and − 500 mV, respectively, after 144 h of NaCl exposure. Microstructural observations confirmed that moderate FA addition refines the pore structure and densifies the matrix through secondary C–S–H formation, reducing pathways for chloride ingress. The study’s novel contribution lies in quantifying the combined mechanical and electrochemical response of FA-modified concrete under chloride attack, particularly relevant for tropical marine environments. The 15% FA replacement is identified as the optimal proportion, balancing early-age reactivity, long-term durability, and sustainability by reducing CO₂ emissions and extending service life of reinforced concrete structures. © The Author(s), under exclusive licence to Springer Nature Switzerland AG 2026.
Department of Civil Engineering, Faculty of Engineering, Universitas Negeri Padang, Padang, Indonesia; The Indonesia State Electricity Company, Jakarta, Indonesia; Department of Civil Engineering, Faculty of Engineering, Universitas Hasanuddin, Makassar, Indonesia
