Costain and Laing O’Rourke have joined forces to trial new ground-breaking tests to measure the strength of sprayed concrete. The new technique, which relies on thermal imaging to monitor sections of sprayed concrete lining rather than the method of checking smaller test panels, is hoped to be a safer alternative, and contractors believe it could help protect site worker from the potential dangers of sprayed concrete lining failures.
Known as Strength Monitoring Using Thermal Imaging (SMUTI), the technique was developed by Cambridge’s University’s Dr Benoit Jones and uses a thermal imaging camera to track the temperature of concrete as it is being sprayed to form tunnel linings. In being able to identify this temperature history, engineers are able to calculate the amount of hydration that has occurred in the concrete, and thus its strength.
The current method of testing involves monitoring only small test panels, which naturally cannot always be representative of the tunnel lining as a whole. The use of a thermal imaging camera also ensures that tests can be conducted from safe distances, and as said by Aled Davies, Costain Senior Tunnel Engineer, to The Construction Enquirer, it is hoped that “SMUTI will eventually become the primary method of early strength monitoring on all tunnelling projects.”