Experimental Investigation of Corrosion Cracking in Reinforced Concrete Beams Containing Nano Wollastonite

Abstract

Cracking of the concrete cover due to corrosion is defined as the serviceability limit state of reinforced concrete structures. This study evaluated the influence of a mineral admixture i.e. nano wollastonite on corrosion performance and serviceability of reinforced concrete structures by performing an accelerated corrosion test on ten reinforced concrete beams under a sustained load. To do so, five concrete beams were treated with nano wollastonite (NCW), while the others were normal concrete beams (NC). The results were discussed in terms of corrosion crack patterns, crack width, half-cell potentials, rebar mass loss, and rebar diameter degradation at different corrosion levels. The results showed that the incorporation of nano wollastonite in reinforced concrete beams increased the service life by increasing the initial cracking time, decreasing the corrosion crack growth rate and rebar mass loss. Given the maximum 0.3 mm corrosion crack width as limit state criteria, the lifetime of the NCW reinforced beams was 3.6 times longer than that of Group NC. The experimental results were compared with existing models. However, these models were unreliable in predicting the steel cross-section loss based on crack width. To solve this problem, a GMDH-type neural network model was developed and evaluated using obtained experimental data for NC and NCW beams.