Effects of sustained loading and pre-existing cracks on corrosion behavior of reinforced concrete slabs

An experimental study was conducted to characterize the structural behavior of reinforced concrete (RC) slabs subjected to accelerated corrosion. Eighteen steel reinforced concrete slab specimens were cast for testing. Transverse cracks were formed in some of the test specimens by applying controlled amount of static loading. Sustained loading was maintained during the entire time of the corrosion process. Three different test conditions were induced: (i) specimens without pre-existing cracks and sustained loading, (ii) specimens with pre-existing cracks but no sustained loading, and (iii) specimens with pre-existing cracks and sustained loading. The crack patterns and crack widths were recorded for each specimen. The final mass loss and the ultimate load carrying capacity after achieving the desired corrosion level were also determined. The results highlight that un-corroded steel reinforced concrete slabs exhibit several bending-induced cracks transverse to the steel reinforcement with a ductile failure mode. Corroded specimens exhibit fewer but wider transverse cracks under bending loads and the failure mode is a brittle failure mode. Pre-cracked initial condition and sustained loading during the corrosion process have noticeable influence on the corrosion behavior of RC slabs. These conditions cause a larger reduction in ultimate load carrying capacity of such slabs compared to slabs subjected to corrosion when there are no cracks and the loading is not sustained in nature during the corrosion process. Ignoring this deleterious performance can lead to unsafe condition assessment.