Electronic Thesis and Dissertation Repository


Doctor of Philosophy


Civil and Environmental Engineering


Hesham El Naggar


Noise barriers (sound walls) are usually constructed along roadways to mitigate the airborne noise emanating from vehicles. They are currently built using various materials including precast concrete panels, masonry, wood and transparent sheets. The main challenge in roadside construction is the obstruction of roadways during the construction, which may result in traffic congestion, public dissatisfaction, car collision and subsequently fatalities. In order to decrease the risk of roadside construction, accelerated and non-obstructive methods are highly preferred by transportation authorities.

An innovative wall system comprised of polyurethane products is proposed, developed and investigated for application in accelerated construction of noise barriers. The proposed sound wall comprises stay-in-place poly-blocks as formwork, two types of polyurethane foam (PF) as structural cores and polyurea as a coating of the wall surfaces. The poly-blocks are stacked layer by layer on the wall footing and form a wall with cylindrical voids. A fast-curing liquid mixture of rigid or light PF is injected into poly-blocks voids to act as the main structural element. Steel rebars connect the PF cores to the wall footing as anchorage system. A polyurea or shotcrete coating is sprayed on both sides of the wall in order to enhance the resistance of poly-blocks surfaces against abrasion, stone impact, weathering, fire development, chemicals and penetration. This construction technique and materials result in less obstruction, faster construction and efficient sound walls in terms of sound attenuation.

A comprehensive experimental program including 80 specimen and 16 full-scale tests was conducted to determine the materials mechanical properties as well as structural behavior of full-scale walls, which were constructed using different PF and rebar arrangements. In addition, three-dimensional finite element models of the laboratory specimens and the full-scale walls were simulated and verified using the experimental results.

The experimental and numerical results indicated that the structural performance of the proposed wall system is satisfactory for the application of noise barrier according to the relevant building codes. Based on practical observations, the wall system can be implemented in an accelerated and non-obstructive construction method. Finally, detailed design guidelines are prepared for various practical conditions.