The development and current state of methods for the nondestructive testing and acoustic tomography of concrete

The development of acoustic methods for the nondestructive testing of concrete during the recent decades is described. The main characteristic problems and tasks of acoustic tomography of concrete are outlined and the evolution of the methods of their solution is analyzed. The advantages and disadvantages of the synthetic-aperture focusing method as a tool for the visualization of the internal structure of concrete are discussed. Possible directions of further progress in theory, as well as practical acoustic tomography methods, including those using phase information, are indicated.