Detection of rebar corrosion by using ground penetrating radar

Abstract

Reinforced concrete has been proven for its versatility, resistance, and longevity but over time it also suffers from deterioration due to different physical, chemical and, mechanical actions exist the concrete. Once the corrosion process starts, there is no way to reverse the process and visual inspection is one of the methods to detect the corrosion. However, it is only effective if there is evidence of corrosion exist from the surface of concrete such as cracks, delamination and spalling. Even though there are several methods to evaluate corrosion, however, most of them have an invasive character since the method requires extracting samples. There are several non-invasive techniques to detect corrosion such as GPR but this technique is not popular since the interpretation of GPR images is very difficult. This research addresses the major issue of assessing the corrosion of rebar inside a reinforced concrete that are invasive and costly since require a large amount of time and man power assess the condition with a simple yet effective method. So, the aim of this research is to detect the corrosion in rebar using GPR non-invasive technique. There are three objectives of this study which are to obtain all the parameters used calculate the radius of rebar, compare the estimated to original rebar size and to test the result validity to ground truthing data. The work starts with finding the suitable site to scan the rebar. 3 block of reinforced concrete beam located in B04, UTM. After the scanning is done, raw data are processed using Reflexw software provided by UTM. Then, the processed data are analyzed and conclusion is made. Findings of this research is that the difference of estimated rebar diameter is 16% differ from the original diameter. This can also be seen from hyperbola. The hyperbola depth is uneven because of the corrosion that disrupts the surrounding of rebar thus affecting the time of the signal to reach the rebar. Also, this statement can be validated by ground truthing data which shows that the rebar is corroded with brownish particles surrounding the rebar that causes by forming of oxide particles. This allows the GPR user to have an extra analysis to their report which is the current condition of the underground object scanned. This statement was proven in this research study as the change in rebar radius was detected to be 16% from the original value. Then, the hyperbolic image was also analysed that indicates the rebar scanned was corroded.