Construction sensor and monitoring specialist Converge has said that it is working on a concrete thermal integrity system for the piling industry through collaboration with Keltbray Piling.
“We have been working together on the piling solution since 2016,” said Converge CEO Raphael Scheps.
“Keltbray had a need for a solution and we already had a product for above ground applications, such as concrete framing.
“The development was a challenge due to the mechanical environment of placing the sensors underground. There is no second chance. However, the technical challenges can be overcome.”
So far the system has been used on four of Keltbray’s projects in London.
According to Scheps, the application has improved quality controls, understanding of the 28 day strength and the ability to handover the piles for breakdown earlier.
“It allows more informed decisions,” he says.
There are four main components to the system. A sensor installed within the concrete monitors the temperature profile over time and is connected to an above ground node that is a wireless transceiver that can send to a Converge repeater or cellular gateway hub that uploads the data to the web-based platform that is used to display the temperature profile and compressive strength data.
“Working with Keltbray has allowed us to take the system from concept to a working product and we hope to have the system commercially available in six to nine months,” said Scheps.
“We are looking at the cost comparison with the conventional approach of testing concrete cubes, but it is difficult to compare because the benefits from the system and cubes achieve different things.”
Framing the benefits
“For the concrete framing sector, the benefits have been three-fold,” explained Scheps. “Firstly, the contractor knows when concrete reaches the target strength and allows them to strike formwork or post-tension earlier – on average this gives a 20 to 30% improvement on floor cycle time. Also, the results are more accurate than cube testing as cubes are tested at 20C which is often not representative.
“Secondly, it adds safety to the process as curing times might be slower in winter due to the cold and the sensors remove the risk of over-estimating the strength. This knowledge has helped reduce tendon failure and adds data for quality control.
“Finally, it is helping to drive sustainability as the sector is gaining clear insight into how the concrete behaves and has created greater understanding of mix design.”
Converge is working on other sensors to build on these benefits and to empower engineers to make decisions based on real data.