When evaluating concrete strength, common opinion is that adequate precisions can be achieved only by a particular or even total destruction. However, such methods are not always applied, besides they are very laborious. The NDE methods have a number of merits, when compared with destructive ones: a possibility to find cracks and hidden flaws in concrete; besides, they show good results in testing materials of other types, such as metals and composites. At the same time, application of NDE methods to concretes is difficult because of their complex internal structure. No existing theory can predict these properties of the transmitted wave. Therefore, the main goal of the present work is to propose a theoretical model enabling the wave penetration of ultrasonic wave through a medium with multiple internal obstacles to be described adequately. Practical applications of this ultrasonic method is toward the evaluation of mechanical properties of concrete, where the influence of internal dislocations, such as pores and cracks, is of significant importance.