The visual impact of “Superstorm Sandy” in October 2012 was quite striking. Storm surges in deserted Manhattan streets that are normally bustling with business-people and noisy taxi drivers, along with the wave-pummeled ruins of landmark fairground rides in New Jersey, brought home the reality of extreme weather conditions – but they only told a part of the story. Even though the storm was not of hurricane force, it caused massive damage to sea defences and the harmful effects were, if anything, greater below the water line than above it. But Sandy was far from the only damaging storm – or even the most severe.
There is constant demand for an effective and economical system to help protect thousands of miles of bulkheads, canals and waterfront homes from ever-more intense storms and rising tidal zones. American company Gulf Synthetics maintains that its PurLoc system will provide newly constructed or re-built seawalls with the strength to withstand harsh marine environments and storm surges, and that it will last longer than seawalls made from traditional materials. PurLoc uses Bayer MaterialScience’s Baydur Pul 2500 polyurethane system.
“Polyurethane composite sheets work and act better in a marine environment than traditional materials such as vinyl, wood, concrete and other composites,” said Mitch Wood, owner of Gulf Synthetics, which is headquartered in Cumming, GA, USA. “With Bayer’s polyurethane and our manufacturing technique, we’re able to create a 100% pure polyurethane composite sheet pile section that is 30% stronger than any other composite sheet pile currently available.” Gulf says that testing has found its seawall solution to be nearly as strong as steel sheet pile. Its polyurethane material is also resistant to the chemical, organic and electromagnetic influences that destroy established solutions. Marine borers attack and eat wood, steel will rust and corrode, vinyl degrades under ultraviolet exposure and concrete will deteriorate as the metal reinforcement corrodes. Strict environmental laws prohibit the use of chemically-treated wood and other solvent-based paints or coatings. Gulf maintains that the shortened life cycle of seawalls built with traditional materials increases the expenses of maintenance and replacement.
PurLoc is manufactured by the pultrusion process and is the first composite sheet pile to use a special urethane injection box, which permits injection of resin through even the most dense layers of roving and fabrics. It works with traditional thermoset resins and with the pure polyurethane family of resins, where glass contents are much higher.
The engineering process was started with a finite element analysis (FEA) study, conducted by Bayer with its PU resin. The study helped Gulf Synthetics design for increased mechanical properties, using Baydur Pul 2500. The company has recently completed a project in Suriname, South America, and is currently involved in five further projects.