Rebar Tying Robot History: From Pliers to ABB Robots

A rebar tying robot does one of the most tiring jobs on a concrete project: twisting wire around the crossing points of steel reinforcing bars so the mat or cage holds its shape while concrete is poured. This post follows that job from the first reinforced concrete patents and the ironworkers who tie bars with pliers, to TyBot on American bridge decks and the robot cells that build rebar cages for precast plants. It covers recent news from Korea and the United States, the ABB robots and RobotStudio software Skanska used to cut cage building time, and what still slows these robots down.

TyBot on its gantry above the rebar mat of the CSVT River Bridge deck in Pennsylvania. Photo: BryceNelson7 / Wikimedia Commons (CC BY-SA 4.0)

How rodbusters tied rebar by hand

The French gardener Joseph Monier patented iron reinforced concrete tubs for plants in 1867, and in 1892 the French engineer François Hennebique patented a full building system of reinforced concrete beams, columns and slabs. Concrete holds up well when squeezed but cracks when pulled, so the steel inside carries the tension. From then on, almost every concrete floor, bridge deck and foundation needed a grid or cage of steel bars inside it. Those bars had to be held in place while the concrete was poured, and the cheapest way to do that was to tie each crossing with a short piece of soft wire.

The Immeuble Hennebique at 1 rue Danton in Paris, the reinforced concrete building of François Hennebique's firm, 2017. Photo: Celette / Wikimedia Commons (CC BY-SA 4.0)

The ironworkers who place and tie rebar are often called rodbusters. A rodbuster carries pliers with a hooked handle and a spring that opens them, a reel of soft annealed tie wire on the belt, and a split bag for the wire and small parts. A single bridge deck can hold tens of thousands of crossings, and before robots each one was tied by a worker bent over the mat. Skanska's Ulf Håkansson told ABB that building rebar cages is one of the tasks "that result in a lot of injuries and where people are doing tasks they shouldn't be doing."

Workers tying rebar by hand for a foundation in Rawanduz, Iraq, 2016. Photo: Hardscarf / Wikimedia Commons (CC BY-SA 4.0)

Early automation moved the work off site. In 2019 the New York startup Toggle was building rebar cages in a Brooklyn factory, where an industrial robot picked up and positioned the bars and people did the final wire tying. It could pre-tie cages up to 25 feet long. Tying itself was automated on the bridge deck. Advanced Construction Robotics, a Pittsburgh company founded in 2016 by Stephen Muck and Jeremy Searock, introduced TyBot in 2018. It rides on a gantry across the deck, finds rebar intersections with cameras and AI, and ties more than 1,100 of them an hour.

US Navy Seabees tie a rebar cage together by hand, 2008. Photo: US Navy via Wikimedia Commons (public domain)

Rebar tying robots on bridges and in precast plants today

Advanced Construction Robotics says the robot has completed more than 4.2 million ties on over 60 projects in 14 states. Its first job in North Carolina, reported in January 2026, was the I-40 Gorge Bridge over Jonathan Creek, where it made 58,215 ties for DT Read Steel, working for Kiewit. TyBot used to be available only as a robot as a service subscription, and the company now also sells it outright.

TyBot's tying head hangs from the gantry over the rebar on the CSVT River Bridge. Photo: BryceNelson7 / Wikimedia Commons (CC BY-SA 4.0)

In early September 2026 GS E&C and Hoban Construction invested in Robocon, a Seongnam company founded in 2020, through convertible bonds, Chosunbiz and Dealroom reported. Robocon's ARON system automates the supply, cutting and bending of rebar before it reaches the crews who place and tie it. The reports framed the deal as Korean builders racing to automate rebar work because skilled labour is getting scarce and expensive.

A round rebar cage on a building site in Germany, 2016. Photo: Ermell / Wikimedia Commons (CC BY-SA 4.0)

ABB robots have already been used for cage building. In a customer story published by ABB, Skanska ran trials with ABB robots and RobotStudio, ABB's offline programming and simulation software, to build rebar cages. The time needed fell from 16 hours per tonne to one hour per tonne. The catch was more design work up front, because every cage had to exist as a 3D model, a digital twin the robots could follow. Building cages near the site in Sweden also meant fewer trucks and boats bringing them in from abroad.

Engineers share a robot cell design through RobotStudio Cloud. Photo: ABB

Where rebar tying robots go next

Skanska's next idea is to move the factory to the job. Håkansson described "flying factories" that are site based, with mobile robots that carry sensors to know where they are. ABB's large arms already work in construction in other ways. An IRB 6700 has printed the concrete walls of the German Red Cross headquarters in Warendorf-Beckum, and a robot of that size could also lift and place long bars in a cage cell. A cage cell needs more than an arm, though. Bars have to be fed in, held in position while the crossings are tied, and the finished cage lifted out, so grippers, fixtures and tying tools all have to work together. Simulating a cell like this in RobotStudio first would show whether the reach and payload are enough.

An ABB IRB 6700 printing the walls of the German Red Cross headquarters in Warendorf-Beckum. Photo: ABB

For homes, the link is prefabrication. ABB robots assemble timber building parts in AUAR's micro-factories, and precast concrete plants are another place where house walls, floors and stairs are made indoors. Every precast part with steel inside needs a mat or cage first, so a robot cell that ties cages would fit that kind of plant. It remains a possibility for now. Our posts on home building microfactories and 3D printed concrete buildings cover the neighbouring technologies.

An ABB robot assembling timber building parts in an AUAR micro-factory. Photo: ABB

Håkansson admits there is an upfront cost and extra design time, though he says the savings are many times larger. Some of the work has stayed manual even in automated cells: in Toggle's factory, people still did the final tying. On site, TyBot needs crews to place the bars before it can tie them, so the robot changes the job more than it removes it. And Håkansson's other worry is people: he told ABB that young people are not interested in doing these tasks by hand.

ABB's GoFa cobot is guided by hand and stops when it senses contact. Photo: ABB

Innovation

AI solutions for effortless ABB robot control.

Automation

Robotics

ceojohntran@chatwithrobot.net

+84905311611

© 2025. All rights reserved.

qtran1215@gmail.com