SPRAY-PAINTING a famous north Northumberland castle doesn’t sound like appropriate treatment for part of the county’s historical heritage.
However Bamburgh Castle is not the victim of grafitti, but subject to novel repair plans to reinforce a rock-face by spraying it with a ‘colour-pigmented fibre-reinforced concrete’.
On the seaward side, the castle stands on a whinstone cliff and while this is relatively hard, it is susceptible to freeze-thaw weathering.
This is a process that occurs when water seeps into cracks in the rock and then expands upon freezing. When the temperature rises, the water melts and repeated freezing and thawing weakens the rock.
Castle director Chris Calvert said: “At one point it’s starting to undermine the curtain wall so we are hoping to have it scaled and then sprayed with coloured concrete matching the whinstone to blend it all together.”
He explained that the work is needed as ‘preventative maintenance’ rather than there being any imminent risk of collapse.
“The wall has been there for a few hundred years and we want to make sure it’s there for the next couple of hundred,” Mr Calvert said.
The area of rock subject to repairs is around 65 metres long and up to six metres high.
In a design statement submitted by Smiths Gore as part of the planning application, it states that the aim of the repairs is to ‘prevent further rock falls, which have recently occurred from the face and are considered a health and safety risk, and which also put the castle walls’ foundations closer to the edge of the cliff at risk of future collapse.’
During the work, ‘the rock face would be lightly scaled to remove smaller loose blocks and then sprayed with a colour-pigmented fibre-reinforced concrete matching the rock colour.
‘The concrete will follow the rough contours of the rock face and be coloured so as not to distract from the existing natural environment and has been successfully implemented at an English Heritage property at Tynemouth Priory.’
Several repair options were considered but the sprayed concrete was the option recommended by engineering firm Fairhurst.
They also said that the work would cost in the region of £25,000 following consultation with a specialist contractor, Rock Solution Limited.