FIELD TRIALS of a new silenced hammer have shown dramatic reductions in noise levels for driven piling, according to UK contractor Aarsleff Piling.
When Aarsleff and its Danish parent company Per Aarsleff were unable to find a piling hammer with the noise reduction required, they opted to design and build their own.
A noise survey by Philip Acoustics for Aarsleff on a piling contract for Persimmon Homes at Weston-Super-Mare showed the Banut 500 piling rig with the silenced hammer was more than twice as quiet as the rig with the standard version.
Average noise levels taken 10m from the pile in front of the rig were 80.2dBA Leq for the silenced version, compared with 87.9dBA Leq for the standard hammer.
Aarsleff says the 7.7dBA Leq reduction is considerable, as a 3dBA cut is equivalent to halving the noise. Results taken at the same positions over the entire pile driving cycle were 'even more impressive', at 76.1dBA Leq compared with 85.4dBA Leq.
Aarsleff Piling managing director Terry Bolsher said the hammer should go a long way to satisfying clients concerned about installing driven piling close to buildings.
'As well as being two and a half times quieter than our standard hammer, it has also proved to be more fuel efcient, '' he said.
Bolsher believes the silenced hammer could mean driven piling will be considered for contracts in noisesensitive sites that are typically carried out by bored piling.
The new hammer has been designed to meet requirements for the installation of 200mm and 250mm square section precast concrete piles, predominantly used in the house building sector, rather than for larger pile sections.
Aarsleff plans to build two more silenced hammers for its eet.