Corncockle Specification

General
Corncockle Quarry is near Lockerbie. Bed thickness varies from 0.25 – 1 m and the quarry can supply blocks of up to 0.6 x 4 x 2 m  There are ample reserves and the quarry is opened as required to replenish stock levels (currently 250 m3).

Petrography 
Corncockle is a pale red brown, non-calcareous, fine to medium grained sandstone of Permian age with dark flecks and coarser laminae occurring occasionally.

Expected Durability and Performance 
It is important that the results from the 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. Sandstone is traditionally acknowledged as generally being a very durable building and paving stone and have been used extensively in many towns and cities in the UK. Corncockle sandstone appears to be a durable stone that will have moderate resistance to acid rain or air pollution. However, the moderate weight loss in the sodium sulphate crystallisation test indicates only moderate resistance to salt damage (for example in coastal locations or from de-icing salts). Frost test results indicate the stone should also have high frost resistance. The compressive and flexural strength of the stone is low for a sandstone in comparison with other sandstones. The density and strength data indicate that the stone should be suitable for use in medium trafficked areas.

Overall, Corncockle should be suitable for use in many aspects of construction including flooring, paving, and load bearing masonry. Caution would be required in using it in heavily trafficked areas or areas where a long service life is needed. The stone is not used for cladding.

Test Results – Corncockle

Safety in Use
Slip Resistance (Note 1)

85

Wet 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)

72.5 MPa

Loaded perpendicular to the bedding plane ambient humidity
2) Bending (Note 1)

6.9 MPa

Loaded perpendicular to the bedding plane ambient humidity

Not Tested

Loaded perpendicular to the bedding plane ambient humidity
Porosity and Water Absorption
1) Porosity (Note 3)

19.5%

2) Saturation Coefficient (Note 3)

0.62

3) Water Absorption

5.7 % (by wt)

4) Bulk specific gravity

2132kg/m3

Resistance to Frost 
Flexural strength after Freeze/Thaw Test (Note 1)

6.1 MPa

Loaded perpendicular to the bedding plane ambient humidity
Resistance to Salt
Sodium Sulphate Crystallisation Test (Note 3)

2.52% Mean wt loss

Resistance to Acidity
Acid Immersion Test(Note 4)

Pass

(Test methods Note 1 = EN1341, Note 2 = EN 1342, Note 3 = EN 1341 /BRE 141, Note 4 = BRE 141)

Tests were carried out at BRE in 2000