Comprehensive index condition assessment of structural concrete based on surface wave techniques

To reliably assess the condition of concrete structures, a surface wave-based comprehensive index has been developed. Considering various factors (e.g., aggregate types) influencing the surface wave-based characteristics, a relative index for concrete condition assessment has presented. To address the conflicts between individual indexes, the weight for each index is determined in accordance with its credibility. The effectiveness of the proposed methodology is verified by using test results from six concrete beams with different void volume ratios. Hereby three characteristics of surface waves (i.e., P- and R-wave velocities, and attenuation coefficient) are used to diagnose the concrete beams. It is found that the comprehensive index has the advantage in handling abnormal measurements of the individual indexes by reducing their weights to lower their influence on the final diagnosis. Comparison of the diagnoses based on the comprehensive index and individual indexes reveals that the comprehensive index performs much better than any other individual index. It matches greatly with the compressive strength of the concrete beams obtained from the destructive test. In conclusion, the proposed methodology presents a single comprehensive diagnostic feature with improved reliability on the fitness of the concrete structures for decision-makers.