Factors influencing half-cell potential measurement and its relationship with corrosion level

The purpose of this research was to evaluate the influences of concrete cover, chloride content, compressive strength and moisture content on the half-cell potential measurement in reinforced concrete structure. The relationship between the level of corrosion and the half-cell potential value was also evaluated. Twenty one concrete slabs with the dimensions of 300 × 300 × 100 mm3 and three concrete slabs with the dimensions of 300 × 300 × 125 mm3 were prepared for various experimental cases; that is, three levels of cover (25, 50 and 100 mm), three levels of chloride content (0.6, 1.2 and 1.8% by weight of cement content) and two levels of compressive strength (17.65 and 20.59 MPa). After curing in water for 28 days, the half-cell potential was measured in accordance with the ASTM C879 every week to detect corrosion under wet-dry accelerated until 140 days. The specimens were then broken to observe the corrosion condition of reinforcement inside them. The results showed that the half-cell potential decreased (more negative value) with the increase of chloride content and moisture content but increased (less negative value) with the increase of compressive strength. The influence of concrete cover was still not definitive. The variation of half-cell potential decreased with the increase of concrete cover, chloride content and moisture content. On the other hand, the variation of half-cell potential increased with the increase of compressive strength. The relationship between the level of corrosion and the half-cell potential was found; that is, the level of corrosion increased with the decrease of the half-cell potential.