Uretek deep injection technology has been used to stabilise the walls of 12th century Scaleby Castle in Cumbria as part of a major restoration project.
Consultant Blackett Ord's site investigation revealed that a wet sand sub-strata was the primary cause of the dangerous outward cant of the stonework. To save it from eventual collapse, a system of underpinning or ground stabilisation was required.
The restoration work needed to be carried out in a way that would not disturb the archaeology of the castle.
'We wanted a solution that would not involve digging out beneath the walls, since this would clearly be dangerous and could possibly speed the demise of the building altogether, ' says engineer Charles Blackett-Ord.
'Conventional underpinning did not appear to be appropriate.
Uretek deep injection technology was selected because it could be carried out without excavating the foundations.'
Uretek engineers were on site for only two days. They drilled a strategically placed series of small diameter boreholes 2-3m into the substrata directly beneath the castle walls. This then permitted the deep injection of Uretek high density polymer resin, which hardens within 15 seconds to a density of concrete but is only one fifth the weight.
As it is injected, the Uretek material naturally fills all the areas of weakness and provides a significant increase in ground bearing strength. As the polymer resin hardens, it also expands, exerting dynamic forces of up to 250t/m 2. The repair project at Scaleby Castle is being undertaken by Historic Property Restoration as main contractor and work for the client, Lord Henley, is being grant aided by English Heritage.
INFOPLUS Marcus Brierley, Uretek, 01695 555014