Engineers at the University of Cambridge help design 3D printed smart wall for Highways England

Researchers have created the first 3D printed concrete wall for a new National Highways trial project.

The new structure has been installed on the A30 in Cornwall. It contains special sensors which monitor the structure which could help identify faults to help with maintenance.

The scheme is a joint project involving Highways England, the University of Cambridge and industry.

It is claimed that the project will be greener too. Headwall structures are normally made in limited shapes from precast concrete, requiring formwork and extensive steel reinforcement, but the new design has no steel reinforcement. The wall gets its strength not from steel, but from geometry instead and takes one hour to print.

The Headwall, a retaining wall built at the inlet or outlet of drainage or culvert pipes are installed to reduce any erosion to the pipe and surrounding areas caused by water flows. It was printed in Gloucestershire at the headquarters of the advanced engineering company Versarien using a robot arm-based concrete printer.

A number of sensors were embedded into the structure by Cambridge University researchers to provide temperature and movement data.

Professor Abir Al-Tabbaa of the University of Cambridge's the Department of Engineering has been developing new sensor technologies.

Her team has also developed various ‘smart’ self-healing concretes. For this project, they supplied sensors to measure temperature during the printing process.

Temperature variations at different layers of the 3D-printed wall were continuously monitored to detect any potential hotspots, thermal gradients, or anomalies. The temperature data will be correlated with the corresponding thermal imaging profile to understand the thermal behaviour of the 3D-printed wall.

She said: “Since you need an extremely fast-setting cement for 3D printing, it also generates an enormous amount of heat.

“We embedded our sensors in the wall to measure temperature during construction, and now we’re getting data from them while the wall is on site.”

In addition to temperature, the sensors measure relative humidity, pressure, strain, electrical resistivity, and electrochemical potential. The measurements provide valuable insights into the reliability, robustness, accuracy, and longevity of the sensors.

A LiDAR system also was used to scan the wall as it was being printed to create a 3D point cloud and generate a digital twin of the wall.

This project will serve as a living laboratory, generating valuable data over its lifespan,” said Al-Tabbaa. “The sensor data and ‘digital twin’ will help infrastructure professionals better understand how 3D printing can be used and tailored to print larger and more complex cement-based materials for the strategic road network.”

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