document: An innovative sound wall system was developed in the University of Western Ontario, and was examined to serve as a vertical extension to the existing sound walls. The wall system (denoted as flexi-wall) consists of stay-in-place poly-blocks as formwork, light polyurethane foam (LPF) reinforced with steel rebars as structural cores and polyurea as a coating of the wall surfaces (Fig. 1). Poly-blocks are interlocking light-weight blocks which are stacked up layer by layer and act as formwork for the LPF cores. The poly-block is 20×20×80cm3 and includes four cylindrical voids with 14cm diameter. It is made of molded low-density polyurethane and weighs approximately 1kg. The poly-blocks are fire-resistant blocks and have an excellent capability to absorb, mitigate and reflect a wide range of noises with unmatched frequency of reflective noise. Polyurea coating is an abrasion-resistant finishing layer, which is sprayed on the surfaces of the wall and sets within 2–3min. This layer also enhances the surface resistance of poly-blocks against stone impact, weathering, fire development, chemicals and penetration. LPF is an expanding liquid mixture which is injected into the poly-block voids and cures within 10min. Steel rebars are epoxied into holes drilled in the existing sound wall to connect the wall extension to its base.
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