Sound absorption characteristics of cenosphere enriched cement and asphalt concrete

A detailed experimental study has been conducted to determine the effect of addition of cenospheres on the acoustic properties of cement matrix and asphalt concrete. Cenospheres are hollow ceramic microballoons, being a waste product of thermal power plants, they are relatively inexpensive and their use has the added benefit of decreasing the strain on the environment. Specimens were made with a different volume fraction of cenospheres (0% to 70% in increments of 10) to observe the change in acoustic properties with an increase in the cenosphere content. Specimens of different sizes were tested to study the acoustic characteristics of the materials for a wide range (125 to 4000 Hz) of frequencies. The effect of an increase in the cenosphere content on the dilatational wave velocity in the specimens was also studied with the help of acoustic transducers. It was noted that, although the wave velocity remains relatively unaffected with a change in the cenosphere content, the addition of cenospheres improves the sound absorption characteristics of the cement matrix and asphalt concrete with a considerable decrease (up to 41%) in the density of the material. It has also been noted that the sound absorption of cement increases with the addition of cenosphere up to 40% volume fraction and starts decreasing with the further addition of cenospheres.