Mechanical and Durability Performance of Metakaolin–Fly Ash Blended Concrete

Durability of reinforced concrete in marine environments is primarily influenced by chloride-induced corrosion. This research evaluates the performance of concrete mixes containing metakaolin (MK) and fly ash (FA) as partial cement replacements (10% and 20%) under simulated saline exposure. Mechanical properties (compressive and split tensile strength) and durability parameters such as rapid chloride penetration test (RCPT), water absorption, sorptivity, half-cell potential, and accelerated corrosion behavior were studied. Results indicate that MK10FA10 exhibited the highest compressive strength (42.2 MPa), while MK20FA20 demonstrated the lowest chloride permeability (1300 C), lowest sorptivity, lowest water absorption, and maximum resistance to corrosion. The combined use of MK and FA significantly enhanced durability, reduced permeability, and delayed corrosion initiation. The study confirms that MK20FA20 offers superior corrosion resistance, making it suitable for marine and coastal construction applications.