---
title: "Empa explores WAAM for repairing steel infrastructure"
url: https://www.voxelmatters.com/empa-explores-waam-for-repairing-steel-infrastructure/
date: 2026-06-26
modified: 2026-06-26
lang: en
author: "Tess Boissonneault"
description: "It's hard to overestimate the importance of steel in our built worlds: the metal is used for everything from bridges to structural frameworks in skyscrapers. Known for its high strength-to-weight..."
categories:
  - "3D Printing Processes"
  - "AM Research"
  - "Metal Additive Manufacturing"
  - "Research & Education"
image: https://www.voxelmatters.com/wp-content/uploads/2026/06/steel-reinforcement-1.jpeg
word_count: 590
---

# Empa explores WAAM for repairing steel infrastructure

It's hard to overestimate the importance of steel in our built worlds: the metal is used for everything from bridges to structural frameworks in skyscrapers. Known for its high strength-to-weight ratio, steel is, however still at risk of damage, whether from corrosion or stress. For the latter case, a team of researchers from Empa, the Swiss Federal Laboratories for Materials Science and Technology, are exploring the use of wire arc additive manufacturing (WAAM) to repair and reinforce damaged steel parts, which could extend the life of vital infrastructure like bridges.

WAAM is an additive manufacturing approach that uses a robotic arm and electric arc to melt welding wire and deposit it layer by layer onto a build surface or substrate. At Empa, researchers are exploring the use of this AM method to apply patches, in a manner of speaking, to damaged steel components, like cracked bridge parts. Considering the difficulty and high costs associated with repairing cracked steel components, this ability could be a game-changer for infrastructure maintenance projects, particularly for repairing fatigue cracks in steel.

This approach is about more than just applying a band-aid, however, as the research team is developing optimized geometries for the reinforcement. As Hossein Heydarinouri, a member of Empa’s Structural Engineering laboratory, explained: "The key isn’t to apply as much material as possible. The shape is much more important: An optimized geometry distributes stresses in such a way that the propagation of existing cracks is stopped or significantly slowed down."

[![Empa explores WAAM for repairing steel infrastructure](https://www.voxelmatters.com/wp-content/uploads/2026/06/steel-reinforcement-2-340x227.jpeg)](https://www.voxelmatters.com/wp-content/uploads/2026/06/steel-reinforcement-2.jpeg)In their research, the Empa team demonstrated how the strategic application of steel reinforcement using WAAM could extend the service life of a damaged steel plate by up to four times. This was determined by printing metal onto cracked steel plates of various sizes and then subjecting them to repeated loading. In all cases, the steel plates with 3D printed reinforcements demonstrated a higher fatigue life than unrepaired plates, while those with two-layer, stepped reinforcement performed best.

Despite the big potential, the researchers have also highlighted some challenges associated with the approach. For one, if the geometry of the 3D printed patch isn't well designed, it can actually lead to new stress concentrations, with the biggest risk being at the point where the printed metal meets the steel substrate.

For another, most WAAM systems are based on industrial robotic arms that can be challenging to transport to infrastructure sites. “Damaged components are usually installed within the structure,” Heydarinouri explained. “Today, they would have to be taken to a workshop for repair, which isn’t always realistic in practice.” Fortunately, there are developments in the sphere of mobile WAAM 3D printers. Until then, Empa sees the biggest impact for the approach being on easily accessible steel components or components that can be removed for repair.

Outside the scope of this project, the Empa team is also exploring the application of metal AM and intelligent geometries for the production of structures that "deliberately yield under extreme loads" and then return to their original shape when the loads are eased. These types of structures could be useful in earthquake prone areas as well as for bridges and technical installations that require vibration resistance. The team also sees applications for components in production machinery that require stress resistance and minimal weight.

Overall, metal WAAM is opening up broad opportunities for repair applications. In the [maritime industry](https://www.voxelmatters.com/category/industry/marine/), for instance, the technology is being explored for on-demand repair applications. “Using 3D printing, we can apply metal reinforcements exactly where they are structurally needed,” said Heydarinouri. “Repairs save material, energy, and costs.”