Chloride Permeability and Corrosion Risk of High-Volume Fly Ash Concrete with Mid-Range Water Reducer

Abstract

This study investigated the effect of local high-volume fly ash (HVFA) incorporating a mid-range water reducer on compressive strength of concrete and on chloride penetration and steel corrosion under tropical climate conditions. The results of electrically accelerated corrosion tests were compared with normal tests. Half-cell potential measurements and visual examination indicated the effectiveness of the corrosion reduction, independent of compressive strengths. A mid-range water reducer improved the 28-day strength by 50 to 75%, compared with 8 to 36% of concrete with 0 to 35% replacement. It also yielded lower chloride permeability and corrosion risk. HVFA concrete with a replacement of 50 to 65% was ranked at greater than 90% probability of no steel corrosion, and the corrosion rank improved from a severe-moderate level to slight or no corrosion at all. Fly ash content, water reducer, and water-binder ratio (w/b), respectively, were three parameters that influenced corrosion risk, while w/b was the most important factor for normal concrete.