Repair cost optimization for maintenance of RC structure subjected to carbonation

Abstract

When concrete is exposed to high concentration of CO2, pH in pore water drops below 10.5 and this allows acceleration of corrosion initiation in concrete, so called carbonation. With increasing significance in durability and maintenance of RC (Reinforced Concrete) structures, maintenance planning based on probabilistic method has been adopted for estimation of repair cost. In the work, repair costs from conventional and probabilistic method are evaluated with increasing intended service life (ISL). The changing probabilistic parameters such as safety index and repairs frequency are evaluated considering extension of ISL and varying coefficient of variation (COV). The effects of ISL and the service life through repair (repair-service life) on repair cost are evaluated, and the two methods are attempted to actual underground structure exposed to carbonation for estimation of repair cost and frequency. Unlike the cost from conventional method, the cost from probabilistic method is plotted as continuous function and is evaluated to be effective to save the repair cost by simply optimizing ISL. Furthermore probabilistic method can consider the uncertainties of construction or repair quality through changing COV of ISL and repair-service life.