A Reliability-Based Condition Assessment of Structural Concrete Using Synthetic Aperture Radar Imaging Techniques

ABSTRACT This paper proposes a probabilistic framework for assessing the condition of structural concrete with respect to moisture contained within cured concrete using a 10 GHz synthetic aperture radar (SAR) imaging system. Functional relationships between integrated SAR amplitude (SAR image index) and moisture content have been developed in previous studies utilizing experimental data collected in a controlled laboratory environment. These studies have shown that the integrated SAR amplitude (SAR image index) increases exponentially with an increase in moisture content at a given water-to-cement (w/c) ratio. In this study, a reliability model is developed using the integrated SAR amplitude and moisture content relationships from an experimental study which included concrete specimens with five different w/c ratios in addition to variations of critical functional parameters and Monte Carlo simulation techniques. The reliability model of moisture content detected with synthetic aperture radar in this study follows a normal distribution. An illustrative example is presented to demonstrate the reliability-based methods of measuring in-place moisture content using an integrated SAR amplitude. The findings from this study emphasize the need to consider the variation of parameters affecting nondestructive SAR imaging results for the purposes of diagnosing moisture content of aged structural concrete.