Impact of Coastal Humidity and Marine Salts on Reinforced Concrete

Structures located in coastal cities throughout the Kingdom endure severe environmental degradation caused by high relative ambient humidity coupled with salt spray carrying aggressive chloride and sulfate ions.

Rebar Corrosion Mechanism: Under normal conditions, fresh concrete maintains high alkalinity (pH 12-13), forming a microscopic passivating oxide layer that shields embedded steel from rusting. However, once chloride ions migrate through moist capillary pores, this passive layer is destroyed, triggering electrochemical corrosion.

Expansive Pressure of Rust: As rebar oxidizes, its volume expands by 2 to 6 times its original dimensions. This generates immense internal tensile stresses far exceeding concrete tensile capacity, causing cover cracking, delamination, and eventual concrete spalling.

Remediation & Preventive Engineering: Rehabilitating coastal concrete demands complete removal of salt-contaminated concrete behind the rebar, mechanical wire cleaning, application of zinc-rich cathodic primer, and rebuilding with silica-fume modified polymer mortar that renders the substrate completely impermeable to salts.