Microstructural Investigation of Compressive Strength and Permeability of Concrete Containing Fly Ash in the Marine Environment of the Persian Gulf

Investigating the impact of fly ash on concrete strength and durability in the challenging marine environment of the Persian Gulf is crucial due to sulfate attacks and salt effects. This study aims to enhance the lifespan of these structures by increasing strength and reducing permeability. The innovative approach involves microstructural assessment of fly ash’s influence on Calcium Hydroxide (CH) and C-S-H nanostructure formation in concrete. Around 120 concrete samples with varying fly ash content were exposed to the Persian Gulf for three months, undergoing compressive strength, permeability, and microstructural analysis. Results reveal fly ash addition decreases permeability and boosts concrete strength. Notably, concrete containing 10% fly ash exhibited a 15.4% strength increase and reduced permeability from 22.4 × 10-7 cm/h to 8.98 × 10-7 cm/h after 90 days. Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray (EDX) analysis showcased CH reduction and enhanced C-S-H nanostructure, bolstering concrete durability. This study offers valuable insights for engineers constructing coastal Persian Gulf structures, indicating fly ash augmentation enhances microstructural properties, reduces permeability, and bolsters strength.