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南非土木工程施工标准 CM1部分：砌体墙 英文原文节选 20100079 2-6 |
4.3.3 Laying and bedding of masonry units
4.3.3.1 Masonry units shall be of the type and class required in terms of the scope of work.
4.3.3.2 Masonry walling shall not overhang concrete foundation slabs by more than 20 mm.
4.3.3.3 Solid masonry units shall be laid on a full bed of mortar with all perpend joints solidly filled
with mortar as the work proceeds. Bed joints shall not be deeply furrowed before the laying of units
and perpend joints shall not be filled by slushing with mortar.
NOTE Perpend joints should be formed by buttering the end of the masonry unit and pressing it hard up
against the end of a previously laid unit.
4.3.3.4 Hollow units shall be laid with the thicker shell uppermost and shall be shell bedded,
horizontally and vertically. The face shells of the bed joints shall be fully mortared. Perpend joints
shall be mortared for a distance from each face at least equal to the face shell thickness of the unit.
(See figure 3.) The webs shall be fully buttered in all courses of piers and columns, in the first
course above a supporting element and on either side of cores, which are reinforced.
4.3.3.5 Each unit shall be laid and adjusted to its final position while the mortar is still plastic. Any
unit which is disturbed to the extent that the initial bond is broken after initial positioning, shall be
removed and re-laid in fresh mortar.
SANS 2001-CM1:2007
Edition 1
22
4.3.3.6 All collar joints in multileaf walls shall have a nominal thickness that does not exceed
20 mm and shall be solidly filled with mortar as the work proceeds. (See figure 4.)
4.3.3.7 All protrusions of mortar that extend more than 15 mm into cores or cavities, and which are
to be filled with infill concrete, shall be removed.
4.3.3.8 All perpend and bed joints shall have a nominal thickness of 10 mm. The bed joint
thickness shall not be less than 5 mm or greater than 15 mm; perpend joint thickness shall not be
less than 5 mm or greater than 20 mm. The thickness of the first bed joint above a supporting
element shall not be less than 5 mm or greater than 30 mm.
NOTE The requirements of 4.3.3.8, namely, that the maximum bed joint thickness of the first bed joint be not
less than 5 mm or greater than 35, might require the use of grade 10 infill concrete to raise the surface of the
supporting member to enable a bed joint of the specified thickness to be achieved.
4.3.3.9 Mortar droppings which fall on face masonry units shall be removed as soon as possible.
4.3.3.10 Bricks that have frogs shall be laid with the frog or the larger frog uppermost. Frogs shall
be filled with mortar as the work proceeds.
4.3.3.11 The perforations in a low density brick shall be filled with mortar where the masonry is
required to spread concentrated loads, such as at bearings to lintels and beams.
4.3.3.12 The cavities of hollow blocks shall be filled completely with concrete, grout, or mortar
where the masonry is required to spread concentrated loads, such as at bearings to lintels and
beams.
4.3.4 Laying in hot weather conditions
In weather conditions of temperatures that exceed 32 °C or in the presence of drying winds, the
length of mortar runs ahead of units which are to be laid, and shall be adjusted to ensure that the
mortar remains plastic when the units are laid.
NOTE In hot or windy weather conditions (or both), units should be laid within 1 min of the bedding mortar
being spread.
4.3.5 Laying in cold weather conditions
In weather conditions where the ambient air temperature is less than 5 °C, masonry units shall be
laid dry. Wet or frozen units shall not be laid.
4.3.6 Rate of construction
The rate of new construction shall be limited so as to eliminate any possibility of joint deformation,
slumping or instability, which might reduce the bond strength.
NOTE The height of walling built in a day should generally not exceed 1,3 m to 1,5 m.
4.3.7 Use of dissimilar materials in the same wall
Masonry units of dissimilar materials (i.e. calcium silicate, concrete and burnt clay) shall not be built
into the same wall unless the different materials are separated by a horizontal damp-proof course or
a vertical control joint. Walls, if of cavity construction, may comprise two leaves of dissimilar
material provided that the reveals and wall ends are not in direct contact with each other.
NOTE Burnt clay masonry units tend to expand and calcium silicate and concrete units tend to shrink. For this
reason, masonry units of dissimilar materials should not be laid in contact with each other.
SANS 2001-CM1:2007
Edition 1
23
4.3.8 Jointing and pointing
4.3.8.1 Joints shall be flush unless another joint profile is specified in the specification data, in which
case the joints shall be finished and compacted to the specified profile with a suitable jointing tool
while the mortar is still green, i.e. before it becomes thumbprint hard. Joints in faces of walls
constructed of hollow units shall not be raked. The depth of any recessed joint shall not exceed
5 mm.
4.3.8.2 Joints in masonry of solid unit construction, which is to be cement plastered, may be raked
to a depth of not more than 5 mm to form a mechanical key for the plaster.
4.3.8.3 Where pointing is required in terms of the specification data, joints shall be raked out to a
depth of not less than 12 mm and not more than 20 mm and shall be filled with mortar mixed in the
same proportions as the original bedding mortar and finished to the specified profile.
NOTE The tooling of the joint surface closes separation cracks, increases the density of the mortar adjacent
to the exposed surfaces and, in some cases, encourages the rapid shedding of water from the corners of the
masonry units and from the joints. In exposed masonry, concave joints and struck joints are most effective in
reducing the risk of rain penetration.
4.3.9 Arches and openings
Temporary supports shall be provided to support masonry in arches and above openings. Such
supports shall only be removed once the masonry has developed sufficient strength to support itself.
NOTE Generally props are provided at 1,2 m centres and are left in place for a period of at least 7 d.
4.3.10 Protection against damage
4.3.10.1 During construction, partially completed masonry, which is not enclosed or sheltered, shall
be protected
a) during any period of interruption caused by inclement weather,
b) at the end of each day, and
c) when work is not in progress.
4.3.10.2 Masonry shall be temporarily braced or otherwise stabilized, as necessary, to resist wind and
other lateral forces during construction, in such a manner that the structural integrity of the masonry is
not impaired.
4.3.10.3 Completed masonry shall be suitably protected against surface contamination, construction
damage, rain and rapid drying out for 2 d, or until built upon or covered, whichever is the lesser period.
4.3.11 Cleaning of finished work
4.3.11.1 Completed masonry shall be free of stains, efflorescence, mortar, infill concrete droppings
and debris.
4.3.11.2 Cleaning down shall be carried out as the work proceeds and again at completion. In the first
instance, masonry shall be cleaned with water and a fibre brush. Thereafter, chemical cleaning agents
may, if necessary, be used strictly in accordance with the manufacturer's instructions, provided,
however, that the work is not damaged.原件下载：  |
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