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Technical Data Sheet
Portland Hard Blue Limestone
Bowers Quarry, Isle of Portland
Contact : Albion Stone Quarries Ltd
Tel. 01737 771 772 Fax. 01737 771 776

email: sales@albionstonequarries.com
website :
www.albionstonequarries.com
Grid Reference: SY 696 730
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 Albion Stone Quarries Ltd and does not represent an endorsement of the stone by BRE.

General
The quarry is situated off Wide Street in Easton on the Isle of Portland. The quarry also produces Whit Bed and Base Bed.

Petrography 
The stone is a dense limestone from the Purbeck Limstone Beds that form the upper part of the Portlandian formation (Jurassic) on the Isle of Portland. 

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 the Portland Hard Blue Bed is a very new product but the results suggest it is very durable and is comparable with Whitbed. It is difficult to compare the results for the Hard Blue Stone from Bowers Quarry to those collected from buildings and exposure trials as the stone has not been used in building construction. However, the overall test results suggest that the stone is strong and of good durability. The crystallisation test results show the stone to be Class A which BRE Report 141 suggests that it is suitable for all uses. When using Hard Blue for flooring care would be needed if the surface were wet as the stone is slippery when wet. The abrasion results indicate that the stone would be hard wearing even in heavily trafficked areas. 

Test Results - Portland Hard Blue Limestone
Safety in Use 
Slip Resistance (Note 1) 
Wet: 36 
Values > 40 are considered safe 
Dry: 57
Abrasion Resistance(Note 1) 
23.0 
Values <23.0 are considered suitable for use in heavily trafficked areas 
Strength under load 
1) Compression(Note 2) 
119 Mpa
Loaded perpendicular to the bedding - ambient humidity 
2) Bending (Note 1) 
13.8 Mpa
Loaded perpendicular to the bedding - ambient humidity 
Porosity and Water Absorption 
1) Porosity (Note 3) 
3.4% 
2) Saturation Coefficient (Note 3) 
0.95 
3) Water Absorption
1.3% (by wt) 
4) Bulk specific gravity 
2596 kg/m3 
Resistance to Frost 
Freeze/Thaw Test (Note 1) 
Not determined 
Resistance to Salt 
Sodium Sulphate Crystallisation Test (Note 14 
Mean: 0.0 

(Test methods Note 1 = prEn1341, Note 2 = prEN 1342, Note 3 = prEN 1341 /BRE 141, Note 4 = BRE 141)

All tests were carried out at BRE in July 1996)

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