Numerical and experimental study on multi-directional SAFT to detect defects inside plain or reinforced concrete

•We proposed a new imaging method to detect defects inside concrete.•The generated image can reveal the geometry of defects.•The proposed method can be used on plain or reinforced concrete.•The demonstration was carried out in numerical and experimental aspects.•Experimental results show good agreement with numerical ones. This paper discusses the feasibility of detecting defects inside reinforced concrete (RC) structures by using multi-directional Synthetic Aperture Focusing Technique (SAFT) to create an image which contains the comprehensive information about the geometry of possible defects. This is achieved by scanning the structure in multiple directions and processing the response data with SAFT and proposed scheme so that the shape and the position of a defect or defects can be completely described. The demonstration was carried out in numerical and experimental aspects. Furthermore the correlation between the numerical and experimental results was analyzed in this paper.