BRE Test results - Blaxter Sandstone

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Technical Data Sheet
Blaxter Sandstone
Elsdon, near Otterburn, Northumberland
Compiled September 1997

This data sheet was compiled by the Building Research Establishment (BRE). It is base on data from tests carried out by BRE in 1996 and by Sandbergs (1996) and information collected in earlier BRE surveys. The data sheet was compiled in September 1997. The work was carried out by BRE as part of a Partners in Technology Programme funded by the Department of the Environment and Dunhouse Quarry Co. Ltd and does not represent an endorsement of the stone by BRE.

General
The quarry is about 6 miles south of Otterburn on the A696 on the right-hand side of the road. This large quarry has been worked since the 1890s and there are older workings nearby. There are good reserves of stone.

Petrography
Blaxter is from the Carboniferous Limestone of Carboniferous age. It is a fine- to medium-grained stone, buff in colour. The stone is available at depths of 1.2m on bed from a 6m face beneath about 2m of overburden.

Expected Durability and Performance
It is important that the results from the from individual tests are not viewed in isolation. They should be considered together and compared to the performance of the stone in existing buildings and other uses. Carboniferoussandstones have been used extensively in many towns and cities in the UK. Blaxter has a long history of use and can be seen in many buildings in the north of England; it has also been used on a large number of restoration projects. Blaxter sandstone appears to be a durable stone that is not effected by acid rain or air pollution. However, the high weight lost in the harsh saturated sodium sulphate crystallisation test indicates limited resistance to salt damage (for example in coastal locations or from de-icing salts). The strength of the stone is towards the lower end of the range for comparable with sandstones but is similar to some of the stronger limestones. Overall, Blaxter should be suitable for use in most aspects of load bearing masonry and cladding but should not be used in areas where a long service life is needed and there are high salt concentrations.

Test Results - Blaxter Sandstone

Safety in Use
Slip Resistance (Note 1)	Not tested	Values > 40 are considered safe
Abrasion Resistance (Note 1)	Not tested	Values <23.0 are considered suitable for use in heavily trafficked areas
Strength under load
1) Compression (Note 2)	38 Mpa 48 Mpa 36 MPa	Loaded perpendicular to the bedding, ambient Loaded perpendicular to the bedding, dry(Note 5) Loaded perpendicular to the bedding, wet(Note 5)
2) Bending (Note 1)	3.3 Mpa 2.6 MPa	Loaded perpendicular to the bedding, ambient Loaded perpendicular to the bedding, wet(Note 5)
Porosity and Water Absorption
1) Porosity (Note 3)	19.6%
2) Saturation Coefficient (Note 3)	0.59 - 0.61
3) Water Absorption (Note 5)	5.8% (by wt)
4) Bulk specific gravity (Note 5)	2120kg/m³
Resistance to Frost
Freeze/Thaw Test (Note 1)	Not tested
Resistance to Acidity
Acid Immersion Test (Note 4)	Pass
Resistance to Salt
Sodium Sulphate Crystallisation Test (Note4)	Mean: Failed (saturated test)

(Test methods Note 1 = prEn1341, Note 2 = prEN 1342, Note 3 = prEn 1341 /BRE 141, Note 4 = BRE 141, Note 5 = ASTM)
with additional data from BRE tests from 1985 and Stangers from 1986