Page 41 - Haddonstone

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Cut ends of galvanised steels must be
coated before use.
Where units are made from two-part
mixes, reinforcement shall neither be
placed within 10 mm of the interface nor
across the interface of the facing and
backing mix, unless the cementitious
binder used in both mixes is identical.
Reinforcement may be required either
for structural or handling purposes only.
Other metal components may be required
for fixing or restraint purposes. These
may or may not be considered as part
of the reinforcement.
8.4.7 Compressive Strength
The average crushing strength of three
cubes tested to BS EN 12390-3 shall not
be less than 35 MPa @ 28 days old. No
individual cube is to have a strength of
less than 28 MPa.
The figure of 35 MPa represents a 40%
increase in compressive strength over that
indicated in the British Standard and is
as a result of research carried out by The
University of Dundee. Note:1MPa is equal
to 1N/mm2.
8.4.8 Capillary Absorption Test (CAT)
When sampled and tested in accordance
with Appendix 2 with an immersion time
of 10 minutes, the mean coefficient of
water absorption due to capillary action
of the three samples shall not exceed
1.0 mg/mm2 with no individual value
exceeding 1.3 mg/mm2.
It should be noted that the recent research the wall ties.
project undertaken in conjunction with
The University of Dundee has identified
that the overall durability of a product
is more likely to be indicated by the
compressive strength than the CAT
figure. The CAT figure is more useful in
determining whether a water proofing/
damp proofing additive has been included.
8.4.9 Sulphate Resistance
Where sulphate resistance is required
(normally in unprotected ground or ground
containing natural sulphates) the suitability
of the units shall be based on the cement
type and content.
8.4.10 Thermal Conductivity
When requested by the customer, the
manufacturer/supplier shall declare the
thermal resistance of the units. The value
shall be established either by testing or
from recognised tables.
8.4.11 Fire Properties
Units manufactured in accordance with
this Standard are non-flammable, non-
combustible, do not give off toxic gases
and can provide a barrier to the spread
of smoke and flame. Standard values
should be referred to for the fire resistance
of walls made from units complying with
this Standard.
8.4.12 Sound Insulation
The sound insulation provided by cast
stone built with units to this Standard is
predominantly influenced by mass per
unit area. The density of the units will
be declared by the manufacturer on
request to enable mass calculations to
be carried out.
Other factors such as the shape of the
units and the air-tightness of the wall also
have an influence. In general, the sound
insulation of a cavity wall is affected by the
width of the cavity, the type and spacing of