|
|
南非土木工程施工标准 MK:路缘石和沟道施工 英文原文节选 20100079 1-40 |
CAST-IN-SITU CONCRETE CHUTES ON SIDE SLOPES OF FILLS AND CUTS.
slopes of fills and cuts together with the inlet and outlet structures, shall be constructed in
accordance with the drawings.
required by the Engineer, a concrete screed shall first be cast in excavations that cannot be accurately
trimmed. The screed shall be accurately finished to the level of the underside of the chute invert slab
and allowed to set before the invert slab is cast.
accurately trimmed, or where chute sides have to extend above the surface of cut slopes, the outer faces
of the sides shall be cast against formwork.
CONCRETE-LINED OPEN DRAINS. Where so specified in the project specification and scheduled, the surfaces
on which a concrete lining is to be cast shall, after being trimmed, be covered with a sprayed bitumen
emulsion primer or polyethylene sheeting of nominal thickness 0,25 mm, all joints in the sheeting being
overlapped at least 150 mm.
sheeting (as relevant) during the placing of reinforcement and during concreting.
Joints in concrete shall be sealed and shall comply with the relevant requirements given in the project
specification or on the drawings, or both. The lining shall be cast in alternate panels and, after the
concrete in the alternate panels has set, the exposed end surfaces shall be painted with bituminous
emulsion as specified in 5.4 for kerbing, channelling, and edging, before the intermediate slabs are
cast.
The exposed surfaces of the concrete linings of open drains shall be given a woodfloat surface finish and
the concrete shall be cured as specified in SABS 1200 G or SABS 1200 GA, as applicable.
BRICK-ON-EDGE KERBING.
shall be laid and bedded in the manner specified in 5.2, and in such a way that the upper surface is
flush with the surface of the sidewalk.
The intermediate sections shall then be cast and the exposed surfaces finished
Cast-in-situ concrete chutes on side
The grade of concrete shall be as indicated on the drawings. If so
Where the material being excavated cannot be
Care shall be taken not to damage the bitumen layer or the polyethylene
Except that the width of joints shall not exceed 12 mm, brick-on-edge kerbing
MACHINE PLACED (EXTRUDED) KERBING AND CHANNELLING
Type of Construction.
detailed on the drawing, by means of machines that comply with 4.1, and using materials that comply with
3.7.
Weather Limitations.
a) while rain is falling or when it is likelyothat rain will fall:
b) when the air temperature is at or bglow 5
temperature is likely to drop below 5
c) when the temperature is above 40 OC on a calm day or above 30
approved precautions against drying out are taken.
Subbase Preparation. The width of the subbase shall extend at least 500 mm beyond the front- face of the
kerbing or beyond the inside edge of the channelling, as relevant, and shall be sufficient to allow the
kerbing/channelling
After the subbase has been finished true to line and level, the foundation for the kerbing or
channelling, or both, shall be excavated accurately so that there is a clearance of at least 10 mm
between the underside of the kerb or channel mould and the subbase. Irregularities in the true line and
level of the subbase shall be rectified with concrete supplied and laid by the Contractor at his own
expense.
A sufficient number of pegs shall be inserted by the Contractor to ensure that the finished kerbing or
channelling, as relevant, is true to line and level.
Kerbing Operat&.
by the Engineer and approved.
Concrete shall be deposited in the machine as quickly as possible after mixing, and placed and compacted
or vibrated by proper tools or apparatus to ensure proper compaction and shape after placing, and to
ensure that a minimum of air is retained in the concrete.
Once concrete has been placed it shall not be disturbed. The placing of concrete shall be carried out as
continuously as possible in order to avoid unnecessary joints.
When concrete placing is to be interrupted long enough for an initial set to take place, an open
expansion joint of width at least 5 mm shall be formed at that point as a clear cut through the section.
The final finished surface shall be steel floated and free of honeycombing and other imperfections. All
concrete that cannot be placed shall be removed from the Site.
Gaps of width 5 - 10 nun shall be cut into the wet concrete at intervals not greater than 2 m on straights
and curves of radius yreater than 20 m. The gaps shall be cut on the exposed faces and approximately
80 X through the concrete section. On curves of radius greater than 4 m but not greater than 20 m, gaps
shall be cut at intervals not greater than 900 nun, and on curves of radius 2 - 4 m at intervals not
greater than 600 mm.
Curing. Curing of concrete kerbing and channelling shall commence as soon as the concrete has hardened
sufficiently to ensurc that the surface will not be marked or stained in any way.
Unless otherwise authorised by the Engineer, curing shall be carried out continuously for 7 d.
shall be done either by covering the exposed surfaces of the concrete with sand or cotton or jute mats,
the sand or mats being kept continuously wet, or, where approved by the Engineer, by the application of
a single coat of liquid membrane-forming curing compound (see 3.8).
BACKFILLTNG. After the concrete work specified in the applicable of 5.2-5.8 has heen completed, the
spaces shall be backfilled with approved material to pavement or shoulder level, as applicable. Such
backfill shall be placed in layers not exceeding 150 mm and each layer shall be watered and thoroughly
compacted to at least 90 % of modified AASHTO maximum density, before the next succeeding layer is
placed.
In the case of kerbs, except where they are constructed in cut, the compacted backfill shall extend for a
distance of 0.5 m behind the kerb face.
Where kerbs and channels are laid after construction of the base, the spaces between the concrete and
adjoining base shall be backfilled with premixed bituminous material.
In the case of chutes, t.he compacted backfill shall be level with the side slope.原件下载：  |
|
|
|
