A new way of testing the strength of sprayed concrete, which could provide a ‘significant step forward for health and safety’, has been successfully tested.
On-site trails of the method have taken place at the Bond Street Station Upgrade (BSSU) project - a joint venture between Costain and Laing O’Rourke on behalf of London Underground Ltd.
The contractors claim this is the first time the new technique has been tested in a production environment.
The Strength Monitoring Using Thermal Imaging (SMUTI) technique is a patent-protected invention by Dr Benoit Jones of Cambridge University. Using a thermal imaging camera, the system tracks the temperature of concrete as it is sprayed to form the tunnel lining.
This temperature history in turn enables engineers to calculate the amount of hydration that has taken place in the concrete, and thus its strength.
In terms of health and safety, this could mean a major step forward, according to Aled Davies, Costain’s senior tunnel Engineer, who worked on the trials.
He said: ‘SMUTI allows us to directly monitor the compressive strength development of sprayed concrete while remaining at a safe distance. This is a substantial improvement over the current method, which relies upon a small test panel being representative of the entire sprayed concrete advance to prevent personnel being at risk from sprayed concrete lining falls.’
He added that ‘the trials have gone very well' and that the data is being analysed.
'We hope to have the results by September, when we will present them to tunnelling sector clients and design partners. We hope to see SMUTI become the primary method of early strength monitoring on all tunnelling projects.’