Petrography | Durability | Test Results
Technical Data Sheet
Portland Base Bed Limestone
Fancy
Beach Quarry
Isle of Portland
Contact
: Portland Unit, Easton
Tel. 01305 820 207 Fax. 01395 820 275
email: sales@bath-portland.co.uk
website
: www.hanson-quarryproducts.com
Grid
Reference: SY689 703
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, Regions and Transport and
Hanson Bath and Portland Stone and does not represent an endorsement of the
stone by BRE.
General
The Fancy Beach Quarry is one the a group currently being
worked on Portland by Hanson Bath and Portland Stone. Both the Whit Bed and the
Base Bed are available.
Petrography
The stone is an open textured oolitic limestone from the
Portlandian formation (Jurassic). The stone is formed from ooliths in a micrite
(fine grained calcium carbonate) matrix.
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 Basebed
is traditionally acknowledged as being less durable than Whitbed but it has been
used extensively where a faster rate of weathering is acceptable or where its
working qualities were required. It is possible to compare the results for the
Basebed Stone from Fancy Beach Quarry to those collected from buildings,
exposure trials and tests on quarry samples collected by BRE during the last 70
years. This shows that the stone compares well with the traditional view of
Portland Basebed. Previous research at BRE has shown that Portland limestone
which has a low saturation coefficient (>0.72), a high microporosity
(>11.0 of the stone by volume) and an increased amount of micritic matrix
will weather more rapidly than Whitbed when used on buildings. The results
summarised on these sheets show that most of the samples tested are of this
type. 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). When using Fancy Beach Basebed 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
- Portland Fancy Beach Base Bed Limestone
Safety
in Use |
Slip Resistance (Note 1) |
N.D.
|
Values > 40 are considered
safe |
Abrasion Resistance
(Note 1) |
N.D.
|
Values <23.0 are considered
suitable for use in heavily trafficked
areas |
Strength
under load |
1) Compression(Note 2) |
62.7 MPa
|
Loaded perpendicular to the
bedding plane ambient humidity |
2) Bending (Note 1) |
8.2 MPa
|
Loaded perpendicular to the
bedding plane ambient humidity |
Porosity
and Water Absorption |
1) Porosity (Note 3) |
20.9%
|
|
2) Saturation Coefficient (Note 3) |
0.70
|
|
3) Water Absorption |
7.1 % (by wt)
|
|
4) Bulk specific gravity |
2144kg/m3
|
|
Resistance to Frost |
Freeze/Thaw Test (Note 1) |
N.D.
|
|
Resistance to Salt |
Sodium Sulphate Crystallisation Test
(Note 3) |
16.2% Mean wt loss
|
|