A combination of multiple nondestructive testing (NDT) methods speeds up the assessmentof concrete and increases the precision. This is why the UIR-Scanner was developed at WarsawUniversity of Technology. The scanner uses an Impact-Echo (IE) method with a unique arrangementof multiple transducers. This paper presents the development of the IE module using numericalmodels validated with experimental testing. It was found that rectangular arrangement of fourtransducers with the impactor in the middle is optimal for quick scanning of area for faults anddiscontinuities, changing the method from punctual to volumetric. A numerical study of voiddetectability depending on its position with respect to the IE module is discussed as well. Afterconfirmation of the findings of models using experimental tests, the module was implemented intothe scanner.