*Article* **Development of Impact-Echo Multitransducer Device for Automated Concrete Homogeneity Assessment**

**Bartłomiej Sawicki 1,2, Tomasz Piotrowski 1,\* and Andrzej Garbacz <sup>1</sup>**


**Abstract:** A combination of multiple nondestructive testing (NDT) methods speeds up the assessment of concrete and increases the precision. This is why the UIR-Scanner was developed at Warsaw University of Technology. The scanner uses an Impact-Echo (IE) method with a unique arrangement of multiple transducers. This paper presents the development of the IE module using numerical models validated with experimental testing. It was found that rectangular arrangement of four transducers with the impactor in the middle is optimal for quick scanning of area for faults and discontinuities, changing the method from punctual to volumetric. A numerical study of void detectability depending on its position with respect to the IE module is discussed as well. After confirmation of the findings of models using experimental tests, the module was implemented into the scanner.

**Keywords:** concrete; NDT; finite element method; experiment; automated inspection; frequency domain; validation
