Petrography | Durability | Test Results
Technical Data Sheet
Monks Park Limestone
Monks Park Mine, Corsham, Wilts
Compiled September1997
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
and ARC Southern Ltd and does not represent an endorsement of the stone
by BRE.
General
The Monks Park mine is off the B3353 in Wiltshire.
The stone is mined 24m below ground in a vast mine which extends for more
than 15 hectares. There are plenty of reserves of stone. The stone is worked
in galleries about 6m high which are supported by stone left untouched
to act as props.
Petrography
Monks Park Stone is an oolitic limestone
from the Great Oolite of middle Jurassic age. It is a fine-grained, buff
coloured stone. The stone appears to be divided into four or more beds
but all produce stone of the same colour and quality. In earlier work,
three 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
the Monks Park 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.
Where more severe exposure conditions are
expected, for example high concentrations of sulphur dioxide or severe
frosts, or where a long life is required then it may be desirable to use
a more durable stone (e.g. Portland Whitbed) for weatherings. When using
Monks Park 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
- Monks Park Limestone
Safety in Use |
Slip Resistance (Note 1) |
83
|
Values > 40 are considered safe |
Abrasion Resistance(Note 1) |
33.1
|
Values <23.0 are considered suitable for
use in heavily trafficked areas |
Strength under load |
1) Compression(Note 2) |
29.3 MPa
|
Loaded perpendicular to the bedding - ambient
humidity |
2) Bending (Note 1) |
4.6 MPa
|
Loaded perpendicular to the bedding - ambient
humidity |
Porosity and Water Absorption |
1) Porosity (Note 3) |
23.8%
|
|
2) Saturation Coefficient (Note 3) |
0.85
|
|
3) Water Absorption |
10.3%
(by wt)
|
|
4) Bulk specific gravity |
2066 kg/m3
|
|
Resistance to Frost |
Freeze/Thaw Test (Note 1) |
Not determined
|
|
Resistance to Salt |
Sodium Sulphate Crystallisation Test (Note
3) |
Mean: 79%
wt loss
|
|
|
|
|
(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
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