Hollow Core Concrete Pty. Ltd. designs and manufactures both reflective & absorptive noise barriers. Sound Trap® being one of them.
Sound Trap® is an open cellular low density cementitious non-structural material. It absorbs, instead of reflects noise, and is ideal for projects like noise abatement on freeways, and general transport applications. Hollow Core first produced the product in 1998, for the Melbourne City Link project.
Due to its concrete like properties, Sound Trap® is a mouldable product. Pigments, paints and special coatings can also be applied to Sound Trap®.
A water proofing coating is commonly applied, preventing the cells from being closed by rain to provide an al weather acoustic barrier.
The reason for the high sound absorbency is that the structure is open cellular.
Under magnification, it looks like this:
Hollow Core Concrete offer a range of textured finishes for noise barriers.