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南非土木工程施工标准 MJ:分段摊铺 英文原文节选 20100079 1-39 |
PLANT
GENERAL. Plant that is operated on or over units that have been laid shall be such that it
cause damage to or disturbance of the units (see 5.6).
ROLLER. A roller shall be subject to approval and shall be a light (2-4 t) vibratory roller or,
required (see 5.6.2), a heavy pneumatic-tyred roller.
passes a
does not
where so
MECHANICAL COMPACTOR. A mechanical compactor such as a flat-plate vibrator of high frequency and low
amplitude, will be acceptable provided that it produces
a) for units of thickness exceeding 80 mm, a centrifugal force of 16-20 kN at a frequency of 65-100 HZ
on a plate area of 0,35-0,5 m2 (i.e. sufficient to cover at least 12 units); or
b) for units of thickness not exceeding 80 nun, a centrifugal force of 7-16 kN at a frequency of 65-100 Hz
on a plate area of 0,2-0,4 m2 (i.e. sufficient to cover at least 10 units).
CONSTRUCTION
PREPARATION
New Work
General. where the paving is to be laid on newly constructed earthworks or on an existing subgrade that
is too low, the subgrade and subbase shall be constructed in accordance with the requirements of SABS
1200 DM and SABS 1200 ME, respectively, and shall conform to the tolerance requirements of 6.2.
Depressions. Depressions shall be filled with material that has the physical properties specified for
subbase material in SABS 1200 ME, and the material shall be compacted to 98 % of modified AASHM maximum
density. Bedding sand shall not, under any circumstances, be used for this purpose.
Fall and level. The top of the subbase shall be so constructed that surface water cannot pond and shall
have a longitudinal fall of at least 1 % and a transverse fall of at least 2 X. The level after
compaction shall be the designated level of the top of the subbase 2 10 mm (see 6.2(b)).
Existing Subbase Substandard or too High
Substandard layers. Substandard layers and soft and unstable areas in the subbase (or subgrade or
formation, as applicable) shall be replaced or strengthened as specified in 5.1.2.2 or 5.1.2.3, as
applicable.
Subbase not stabilized. Any portion of an existing subbase that has not been stabilized and is too high
shall be lowered, harrowed and reconstructed to such depth that, after compaction, the subbase layer is
of the same standard and thickness throughout or it shall comply with the requirements of the project
specification and, in addition, the fall and level shall comply with 5.1.1.3.
Stabilized subbase. Any portion of an existing stabilized subbase that is too high shall be lowered,
harrowed and reconstructed to such depth that, after compaction, the subbase layer is of the same
standard and thickness throughout or it shall comply with the requirements of the project specification
and, in addition, the fall and level shall comply with 5.1.1.3. Depressions created in the course of
lowering a stabilized subbase shall be filled with stabilized subbase material and compacted to form a
subbase of at least the same standard as that of the existinq stabilized subbase. Alternatively, in the
case of depressions of depth greater than 50 nun, concrete having a 7 d cube strength of at least 5 MPa
shall be used. The fall and level after compaction shall comply with 5.1.1.3.
EDGE RESTRAINTS. Edge restraints consisting of kerbs or channels (see 3.2) or other approved edge
strips, as scheduled or given on the drawings, shall be constructed on the subbase (or other specified
formation) before any units are laid.
PLACING AND COMPACTING OF SAND BED. Bedding sand shall be spread over the subbase and evenly screeded in
the loose condition so as to achieve a compacted thickness of 25 2 10 nun. When the sand is spread, its
moisture content shall be 6 2 2 %. The sand bed shall be laid slightly in advance of the placement of
the units but only to the extent that the particular area of pavement can be completed on the same day.
Where the sand bed is accidentally compacted before the units are laid, it shall be raked and evenly
rescreeded in a loose condition.
LAYING OF UNITS, The principal lines of the paving unit pattern as laid shall be as specified in the
project specification or given on the drawings, and as agreed with the Engineer before laying commences.
If the said principal lines are not so specified, given or agreed, the units shall be laid in a
herrinqbone pattern if the block shape permits and, where units cannot be so laid, they shall be laid
with the long axis at right angles to the line of traffic. Except where curved patterns are required,
the lines of the unit pattern shall be visually straight and parallel to major kerbs or buildings or
other structures, as most appropriate and as approved.
Where appropriate, lines shall be set up at right angles to each other to control the alignment of the
units. Joint widths shall be between 2 nun and 6 mm.
Whole units shall be laid first. Full depth closure units of special size or cut or part units split
from whole units, shall be fitted into gaps around the perimeter and around service installations such as
manholes.
Where plant has to be moved over an uncompacted newly laid pavement, boards shall be laid to prevent
disturbance of the units.
FILLING GAPS IN UNIT PATTERN. Each gap where a closure unit cannot be used, shall be filled, after
thorough pre-wetting of all units bounding the gap, with concrete that has a 24 h cube strength of at
least 15 MPa and contains aggregate of maximum nominal size 9,s mm. Filling shall be kept to an absolute
minimum and shall be to full unit depth in all cases. The concrete shall be cured for at least 24 h by
covering it with moist sand or approved plastics sheeting or hessian firmly held down at the edges.
Where concrete is used for filling gaps, no compaction shall be carried out within 1 m of such filling
until 24 h after the filling has been completed or until the specified cube strength of 15 MPa has been
attained, whichever occurs first.原件下载： 
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