FREQUENCY-DEPENDENT STRESS WAVE ATTENUATION IN CEMENT-BASED MATERIALS

Ultrasonic techniques are a widely used, reliable form of nondestructi ve testing of materials. The nature of concrete as a heterogeneous mix ture makes it somewhat ill-suited as a conductor of stress waves, and therefore makes the interpretation of ultrasonic data difficult. In or der to quantify the attenuation of ultrasonic waves in concrete, a poi nt source/point receiver (PS/PR) ultrasonic test system was set up, an d the individual components were evaluated. PS/PR can be used to quant ify (among other things) the ultrasonic attenuation in the materials. The technique was applied to a series of four portland-cement-based te st specimens. These specimens ranged from a fine cement paste to concr ete sample with a maximum aggregate size of 10 mm. The frequency-depen dent attenuation was evaluated for each specimen. The results of this investigation showed that the wave-propagation characteristics of the materials can be quantified with this technique, and that certain char acteristics of the attenuation curves can be linked to the degree of i nhomogeneity in the material.