A system of monitoring diffuse waves over a concrete beam under different loads. Ultrasound transmitters and receivers are placed over the concrete beam to emit sound waves and collect diffuse waves under different loads. The waveform variations are observed to quantify a decorrelation coefficient (DC) indicating global structural changes and crack position. An inversion of the correlations is applied to estimate distribution density at each localized position following the sensitivity kernel and inversion algorithms. Then, three-dimensional imaging comprised of density values at each localized position are generated to indicate number, position, and depth of multiple cracks.