Effect of Preloading and Nano-Silica on Structural Behaviour of Corroded R.C. Beams

Reinforced concrete structures are considered as permeant structures that can be used for a long time. But, one of the most issues has been discussed in construction community was corrosion of embedded steel bars. Corrosion has a negative significantly effect on the behavior of reinforced concrete structures where decrease bar cross section, formats massive products, reduces bond between concrete and steel bars and also, reduced load capacities. To simulate corrosion under loading condition, the specimens were subjected to preloading before corrosion process. Also, addition of nano-silica to concrete mixes with variable ratios was studied to show its effect on corrosion rate. 8 beams were divided into two groups (A and B) with preloading and unloading respectively. Then, all beams were corroded accelerable. 4 concrete mixes were designed. The experimental result included compressive strength of concrete, corrosion cracks pattern, steel mass loss and ultimate flexural load. Finally, it was noticed that preloading had negative effect in steel mass loss, ultimate load, and increased cracks. On contrary, addition of nano-silica improves the structural properties of corroded beams.