Investigation on Corrosion Behaviour of Polymeric Coatings on Weathering Steel Under 3.5% NaCl Solution

Weathering steel, a low carbon alloy steel, most widely used in marine transportation and construction fields like bridges, sculptures where corrosion resistance is the main concern. Weathering steel creates an adhering protective coating on its surface in the right environmental conditions. The protective layer which is formed on the surface weathering steel known as patina. It protects the structure from further corrosion to occur. When these weathering steels are continuously exposed to moisture environment its corrosion resistance decreases. So, our investigation deals about the studies of the coatings used on weathering steel to increase its corrosion resistance in marine conditions. The coatings applied on the substrate were poly urea, polyurethane, epoxy and black enamel. Corrosion tests were performed on these coated samples to evaluate their corrosion behaviour in different environments. Corrosion tests that were performed are immersion test, salt spray test and potentio-dynamic test. The profilometry test is investigated and it confirmed the depth of the corrosion on the coatings. Based on the corrosion studies, we conclude that poly urea is the excellent coating followed by polyurethane, black enamel and epoxy.

Grand Avenue Traverse: Uniting Accessibility, Utilities and Economy Into a New Experience

<p>The Grand Avenue Pedestrian Bridge spans 85m from a park and residential neighborhood to a developing waterfront district that is 24m below. The bridge carries sewer, storm, and water utilities over rail lines and a highway while passing under power lines. The bridge’s east landing is on a landslide prone steep slope. On the west the bridge lands on a new concrete stair and elevator tower that rests on soil that is regularly infil- trated with seawater.</p><p>The design concept uses the constraints of the project to create a unique moment that is both utilitarian and unexpected. By sloping the truss to drop 4.8% towards the west, a set of accessible ramps are created on the top, side, and interior of a box-truss style bridge. Traversing 7m of elevation through accessible paths allowed the design team to minimize the height of the elevator and therefore moment into the foundations, critical for a site that is seismically active and located in seawater infiltrated soil.</p><p>Material choices for the bridge and throw barrier were based on considerations of durability and mainte- nance. Weathering steel is used for the primary truss members, painted steel for members located under the deck, and bare aluminum panels with a custom CNC cut perforation form the guardrail and throw barrier. All of the elements come together as a unified experience.</p>