Currently, there are more than 620,000 bridges across the United States, out of which 7.5% are considered
structurally deficient [1]. When a bridge is given a ”poor” condition, it immediately closes to traffic due to safety protocols and will only open after repairs have been applied to it. However, current repairs are expensive, labor intensive and require many resources.

Bridge deterioration occurs due to a multitude of factors, including weather-related wear and tear, heavy vehicular loads, and insufficient maintenance. Deteriorated components often cannot be repaired and as a result a replacement is needed due to the lack of effective restoration methods. A possible new repair method for corroded steel bridge beams is cold spray additive manufacturing (CSAM), where the substrate is being treated by an oxide-free deposit without damaging the underlying substrate thermally. In this process, a high temperature compressed gas (nitrogen) is used to accelerate the metal powder feedstock, reaching all the way up to 300 m/s and beyond. With cold spray, it is possible for a bridge beam to retain its original capacity using targeted and limited added material. A so called bond is created between the substrate and the powder ensuring the ability to retain capacity.

In recent years, the use of CSAM applications has grown significantly due to the low working temperature, less product size limitations and one order of magnitude higher deposition rates compared to other established additive manufacturing techniques [2]. The current study discusses a new state-of-the-art application where CSAM is introduced for additive repair of corroded steel bridge beams. Through a collaboration between MassDOT, UMass Amherst and MIT, the research team tested cold-spray repairs on naturally corroded substrates that have been obtained from deteriorated bridges in the New England region. Several types of tests with tensile coupons and compression pillars have been performed and
research is currently expanded towards fatigue and bending strips. Furthermore, the focus will be on moving from a lab environment to the field using portable equipment. With that, process parameters are tested outdoors to deposit repair on steel corroded elements with CSAM.

Our results highlight that beams repaired by CSAM can retain significant capacity in comparison to the volume of metal added. Furthermore, the repair is precise and could be performed directly in the field. This gives the opportunity to possibly prevent extensive repairs, that could lead to load- and weight restrictions or even closure for a longer time.

Date and Time
Thursday, November 7, 2024
1:30 PM - 3:00 PM

Location
Newport Room

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