Technical Data Sheet
Westwood Ground Limestone
Bradford on Avon, Wilts
Contact : Portland Unit, Easton
Tel. 01305 820 207 Fax. 01395 820 275
email: [email protected]
website : www.hanson-quarryproducts.com
Grid Reference: ST 803 591
Compiled September 1997
This data sheet was compiled by the Building Research Establishment (BRE). Where possible, data collected in earlier surveys has been used to help interpret the test results. The data sheet was compiled in September 1997 using the results of tests carried out to the proposed European Standards. The work was carried out by BRE as part of a Partners in Technology Programme funded by the Department of the Environment, Transport and the Regions and Hanson Bath and Portland Stone and does not represent an endorsement of the stone by BRE.
The mine is in the village of Westwood. It is on the hill above Avoncliff. The entrance to the mine is on the side of the hill and this gives access to the face which is below ground. The mine was reopened in 1975 and there are plenty of reserves of stone.
Westwood Ground Stone is an oolitic limestone from the Great Oolite of middle Jurassic age. It is a corse-grained, buff coloured stone. The stone is divided into two beds in a 2.3m deep face. The top bed is between 600m and 750mm deep, whilst the lower bed is up to 1.2m deep. In earlier work, the two beds were tested but had similar porosity and water absorption values.
Expected Durability and Performance
It is important that the results from the sodium sulphate crystallisation tests are not viewed in isolation. They should be considered with the results from the porosity and water absorption tests and the performance of the stone in existing buildings. Stone from Westwood is traditionally acknowledged as being less durable than stones such as Portland Whit Bed but it has been used extensively where a faster rate of weathering is acceptable or where its working qualities were required. When using Westwood Stone it is especially important that the detailing of the stonework is designed to offer the maximum protection to rainwater and rainwater runoff. Based on current research it seems likely that the stone would weather at a rate of between 3 and 4 mm per 100 years but it could be greater in severe exposures or on the edges of stonework.
Test Results – Westwood Ground Limestone
(Test methods Note 1 = prEn1341, Note 2 = prEN 1342, Note 3 = prEn 1341 /BRE 141, Note 4 = BRE 141)
Tests were carried out at BRE in 1996 N.D. = not determined