Verification of the ability of selected acoustic methods to detect the amount of steel fibers in concrete

The use of different fiber types (polypropylene, steel, glass, natural fiber) to cement based materials for better performance is becoming more and more frequent. The addition of fibers increases the mecsshanical characteristics of these composites. This paper examines the cement based composites reinforced by steel fibers. We focused on the relationship between the amount of steel fibers (40, 80 and 120 kg on 1 m³ of concrete) and changes of parameters of acoustic waves which pass through the material. For non-destructive evaluation the two pulse-echo methods were used. First of these pulse-echo methods used as impactor the steel hammer and the second one used electronic ultrasound transmitter. The aim was to verify the ability of these methods to determine the amount of steel fibers in concrete.