COMPOSITES TO STRENGTHEN SEASIDE INFRASTRUCTURE
Composities, says Francesco Ierullo, head of sales for the Americas region at Exel Composites, offer longer service lives and reduced maintenance compared to steel.
He says that composite materials are becoming popular reinforcements for structures found on the seafront including walkways, bridges, seawalls, and floating harbor decks,and more.
“Aging infrastructure is a well-documented global problem on seafronts, where salty, humid ocean air causes metals to corrode rapidly. Local governments must carry out frequent, time consuming, and disruptive repair jobs, costing billions of dollars, so that structures remain safe and durable.”
Concrete’s biggest weakness he says is its low tensile strength, traditionally remedied by using steel rebar reinforcements.
“However, a disadvantage of using steel in a concrete structure is that it is susceptible to corrosion.” When rust forms around a steel rebar, the internal pressure will increase and the concrete will crack, exposing the steel to more moisture, salt, and humidity.
Swapping out steel rebar with composites in seaside environments provides several key advantages, says Ierullo. Firstly, carbon fibre and fibre glass composites are naturally corrosion resistant, ideal for short- and long-term immersion in seawater. This property is determined by choosing high performance premium grade resins, which ensure low water absorption and protection from aggressive chemicals.
“Furthermore, composites don’t require additional coatings, such as electroless nickel plating or zinc galvanisation for stainless steel, to tackle corrosion. Traditionally used to treat steel rebar the protective layer wears away over time, adding an extra step in production and adding to ongoing maintenance costs.”
Secondly, adds Ierullo, because composites are lightweight, they are much easier to install as reinforcements in bridges and walkways. A fibreglass rebar is approximately one quarter of the weight of a steel rebar, meaning companies can transport more profiles to the site, saving on transportation costs. Furthermore, because fibreglass is lighter than steel, it’s easier for installation crews to carry, helping to promote job site safety. Modern composites also perform better with regards to torsion and tension. Fiberglass has a higher tensile strength compared to steel, making it ideal for structural support in a bridge or walkway.
“For seaside applications with cyclic loading, reinforcing materials must have good fatigue resistance. Seawalls, for example, must endure persistent, high-energy forces from waves to protect land from flooding and coastal erosion. Because of their tensile strengths, composite sheet piles thrive because they can withstand exceptional force without fragmenting.
“These mechanical properties are non-negotiable for civil engineers needing long life, durable solutions with low whole-life costs. Through a process called pultrusion, fibres are pulled through a resin bath and cured in a heated die, before being cut to their desired lengths. The process is highly automated, which ensures continuous, high-volume production of composite sheet piles and rebars at a consistent quality compared to manual manufacturing techniques.”