MOWLEM Civil Engineering has used remote-controlled water jet technology to cut concrete while widening a bridge deck in the Drake Circus refurbishment in Plymouth.
The hydrodemolition technique, using a hired-in Conjet 322 robot, was specified to enable removal of concrete while leaving existing reinforcement in place, ready for a cast extension to the bridge deck.
Mowlem's senior bridge engineer, Hrach Agobiani, said: 'It was a contract requirement to use hydrodemolition to avoid damage to surrounding concrete from vibration.
'It leaves an uneven, textured finished, which gives a strong bond for the concrete we cast on later.'
The contractor originally specified hand-held jetting lances but opted for the remote controlled option to eliminate risk and to raise productivity.
The plan had been to remove all the 0.5 m depth of concrete in a 30 m-long, 0.9 m-wide section but the concrete proved to be so strong it was considered necessary to remove only a 0.15 m-deep channel.