CIVIL WORKS SPECIFICATION
For
FIJI NATIONAL UNIVERSITY
PROPOSED THREE STOREY BUILDING
FOR FIJI MARITIME ACADEMY, SUVA
March 2018
(Tender Issue)
FNU – Proposed Three Storey Building for Fiji Maritime Academy, Suva
Civil Works Specification
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Table of Contents
1. Clearing, Earthworks, Site Works and Road Formation 4
1.1 GENERAL 4
1.2 CLEARING & GRUBBING 4
1.3 STRIPPING 4
1.4 TOPSOIL 5
1.5 EARTHWORKS 5
1.5.1 CLASSIFICATION OF MATERIALS 5
1.5.2 EXCAVATION 6
1.5.3 Foundation Preparation 7
1.5.4 Placing Fill Between Under Sub-Base 8
1.5.5 Fill Moisture Control 8
1.5.6 Fill Compaction 9
1.5.7 Compaction Criteria 9
2. PAVEMENT SUB-BASE 10
2.1 GENERAL 10
2.2 MATERIALS 10
2.2.1 Description 10
2.2.2 Definitions 10
2.2.3 Extraction 11
2.2.4 Source Rock 11
2.2.5 Product 11
2.2.6 Water 14
2.3 CONFORMITY WITH DRAWINGS 14
2.4 SPREADING 14
2.5 TEST ROLLING 15
2.6 PROTECTION OF COMPACTED LAYERS 15
3. STORMWATER DRAINS 16
3.1 SCOPE 16
3.2 PIPES 16
3.3 COMPONENTS - CESSPITS, MANHOLES 17
3.4 MATERIALS 17
3.4.1 Pipes & Precast Reinforced Open Concrete Box Culverts Including ACO
Drains 17
3.4.2 Concrete 17
3.4.3 Cement 17
3.4.4 Reinforcing Rods 17
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3.4.5 Mortar 18
3.5 CONSTRUCTION OF ALL CAST IN-SITU ITEMS 18
3.5.1 Placing concrete 18
3.5.2 Boxing 18
3.6 EXCAVATION AND BACKFILLING 18
3.6.1 Excavation 18
3.6.2 Backfilling 19
3.6.3 Subsoil Water 19
3.7 PIPE LAYING PROCEDURE 19
3.7.1 Bedding 19
3.7.2 Laying 19
3.7.3 Testing of Stormwater Pipes 20
3.8 Headwalls and Outfall Structures 20
3.8.1 EXCAVATION 20
3.8.2 LAYING 20
3.9 DRAINAGE TRENCHES AT BASE OF RETAINING WALLS 21
3.9.1 DRAINAGE TRENCH: 21
3.9.2 DRAINAGE PIPE 21
3.9.3 TRENCH BACKFILL 21
3.9.4 CONSTRUCTION 22
4. CONCRETE, FORMWORK AND REINFORCEMENT FOR PAVEMENT 23
4.1 SCOPE 23
4.2 MATERIALS 23
4.3 FORMWORK 26
4.4 SURFACE FINISH 27
4.5 REINFORCEMENT 29
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Civil Works Specification
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1. CLEARING, EARTHWORKS, SITE WORKS AND
ROAD FORMATION
1.1 GENERAL
The works under this section of the Specification comprises the clearing, stripping, earthworks and
construction of road formation to the specified subgrade levels.
This Specification shall be read in conjunction with AS 3798, "Guidelines on Earthworks for
Residential and Commercial Developments".
1.2 CLEARING & GRUBBING
Clearing includes the removal of all trees and other vegetation, rubbish, stumps, pipes, fences, stone
walls, surface boulders, or other material that is not required in the finished contract.
Certain trees may be designated for saving, and these shall be carefully preserved. The landscaper
land architects approval must be obtained prior to removal of any trees.
Clearing shall include all the area affected by excavation and filling together with sufficient additional
area on which to stockpile stripped topsoil, and may also include further areas as shown on the plans
within the area of the development or subdivision.
Cleared material may be burnt on site unless otherwise directed, and provided such burning is allowed
by the relevant Authorities and carried out in compliance with their requirements. The Contractor is
responsible for obtaining a fire permit, and for any costs relating to such. All ash and residual material
from burning shall be removed from the site. The Contractor is responsible for establishing a tipping
point for all other rubbish, and for any fees relating to such.
1.3 STRIPPING
The area on which the fill is to be placed and the area from which the cut is to be removed should be
stripped of all vegetation and of such soils as are deemed by the Consultant Engineer to be unsuitable
to support the proposed loadings or for incorporation in fills. Topsoil will need to be stripped to spoil
as unsuitable material or stockpiled in positions as required for subsequent re-vegetation. Any
material which the Consultant Engineer considered will inhibit or prevent the satisfactory placement
of subsequent fill layers will not be allowed to remain in the foundations of fills or will be treated as
directed as directed by the Consultant Engineer.
Stockpile locations will be subjected to the approval of the Consultant Engineer, and regardless of
this approval will be chosen so that they are unlikely to initiate instability of either the stockpile or
the natural ground. Stockpile sites will also be chosen so that the stockpile does not inhibit natural
drainage of the area.
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1.4 TOPSOIL
Topsoil shall be removed over the area which will be occupied by the complete works plus a
clearance of 2 metres. Topsoil shall be placed in a stockpile clear of the work to enable its re-use in
landscaping and re-vegetation.
Unsuitable material includes topsoil, peat and other highly organic soils, logs, stumps, perishable
material, rubbish, material susceptible to spontaneous combustion, free draining susceptible to
scouring, very fine sand, silt and organic clay and material with a CBR<1. Such material shall be
excavated and disposed off-site except for top soil required for vegetation. Dispersive soils can be
used only in accordance with guidelines provided by a Geotechnical Engineer. Where unsuitable
material exists in excessive depths the advice of a Geotechnical Engineer is required. The Contractor
shall lightly scarify the surface of the areas to receive topsoil to a depth of 50 mm. This shall be
achieved by use of a rigid fine harrow making at least 3 passes or an approved alternative method.
Topsoil shall be spread over the prepared surface in sufficient quantity to result in a compacted
thickness 100 mm or thicker to make use of all topsoil stripped from the site. The placed topsoil shall
be lightly harrowed to give a uniform appearance and compacted by flat rolling.
The Contractor shall restore any areas where significant gulleying or erosion occurs during the
maintenance period. The Contractor shall make all allowances for restoration, including re-spreading
topsoil, in his lump sum tender price.
1.5 EARTHWORKS
1.5.1 CLASSIFICATION OF MATERIALS
Excavated materials shall broadly be defined as:
a) Earth:
That material which can be excavated and removed directly by normal, modern well operated
mechanical excavating plant. Any soft rock capable of being broken out by Caterpillar D8
size tractor in good working order fitted with a single shank ripper and operating on a near
horizontal surface will come into this category.
b) Hard Rock:
That material which cannot be ripped by a Caterpillar D8 sized tractor in good working order
fitted with a single shank ripper and operating on a near horizontal surface requiring either a
larger machine or the use of explosives to break up before being handled by mechanical
equipment. When the Consultant Engineer is satisfied that blasting techniques are necessary
he shall require evidence from the Contractor that a qualified explosives expert is being
employed and that all appropriate statutory regulations are being observed. When hard rock is
believed by the Contractor to have been encountered he shall immediately notify the
Consultant Engineer who shall rule as to whether the material is hard rock and if so make an
assessment of the volume to be excavated.
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Incidental hard rock boulders occurring within the limits of the earth of greater than one
cubic metre shall rank as hard rock; and those of smaller dimensions as earth
c) Unsuitable or Saturated Materials
Where materials have to be excavated by special machinery (such as draglines) and
techniques due to its situation and nature. All cost relating to treatment and or disposal of all
unsuitable material including loading onto trucks for disposal off site or for spreading drying
sufficiently and re-use as bulk fill on site as directed by the Consultant Engineer shall be
included in the Contractor’s lump sum tender price.
No placing or backfilling shall commence until the Consultant Engineer has inspected and if
necessary levelled the excavation.
1.5.2 EXCAVATION
a) General
Excavation shall be by means of scrapers, bulldozers, hydraulic excavators, loaders, and
trucks or other self-propelled bulk earth-moving machinery.
The Contractor shall ensure that the excavated surface is free draining at all times and stockpile
material in a manner that it is free from water contamination. Should the material become
unsuitable, he shall treat or replace the material as directed by the Consultant Engineer at his
own expense.
In pricing bulk earthworks, the Contractor shall allow for all costs associated with the
excavation, uplifting, transporting, placing and compacting as specified and shown on the
Drawings
Excavation shall be completed to the limits and grades shown on the plans
b) Benching
Shall be carried out where fill is to be placed on sloping ground (generally steeper than 6
horizontal to 1 vertical) These benches shall be cut nearly horizontally with fall towards the
fill area and shall be free draining. The width and height of the bench will depend on the
original ground slope. The rear batter of the bench shall have a slope of about 1 horizontal to
2 vertical, unless otherwise approve by the Consultant Engineer.
c) Limits of Excavation
Care shall be taken that ground beyond the limits of the work shown on the plans is not
disturbed by excavation procedures. Any slips which occur as a result of negligence on the
part of the Contractor shall be made good at his cost and as directed by the Consultant
Engineer.
Excavation shall be carried out to the lines, levels, dimensions and slopes shown in the
Drawings. The excavated faces shall be neatly trimmed and the top edges of the cuttings neatly
rounded. Under cutting of slopes will not be permitted under any circumstances.
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Excavation shall be carried out in such a manner as to prevent erosion or slips, working faces
shall be limited to safe heights and slopes, and surfaces shall be drained to avoid ponding and
erosion.
Overhanging, loose or unstable material likely to slip should be cut back removed or stabilised.
Rock cuttings and exposed rock surfaces shall be excavated so as to obtain smooth, uniformly
trimmed surfaces. Batters in cuttings shall be carried around curves in an even and regular
manner. Finished batters shall not have a slope steeper than that specified.
d) Quantities
Quantities shown in drawings are indicative only and the Contractor must make his own check
on their accuracy and price his tender accordingly.
The volumes scheduled are solid volumes as determined from the longitudina1 sections, cross
sections, or standard details provided
The Contractor must allow for overbreak in determining his price for rock excavation - either
bulk, or in trenches.
1.5.3 FOUNDATION PREPARATION
The ground surface exposed after stripping and on which fill is to be placed shall be shaped to assist
drainage. The exposed surface shall then be moisture conditioned to within the range of 85% to 115%
of the optimum moisture content as determined in the standard compaction test and the upper layer
of not less than 150 mm shall be compacted to a minimum dry density ratio of 98% Standard Proctor
(AS 1289.E4.1). Any soft or unstable areas exposed during this compaction process are to be treated
by further moisture conditioning or by excavation and replacement with selected fill material. This
replacement fill is to be compacted to a minimum dry density ratio of 98% Standard Proctor. No fill
shall be placed on the prepared foundation prior to it being inspected and approved by the Consultant
Engineer. At the time of his inspection, the Consultant Engineer may request the contractor to test
roll the foundation area or perform compaction tests.
The Contractor must allow in his lump sum tender price for all works associated with foundation
preparation, inspection and test rolling. If the Contractor believes he has carried out sufficient
moisture conditioning and compaction work, and that the soft or unstable areas are due to weak
foundation soils, he shall notify the Consultant Engineer who will then assess the preparation works
carried out and advise on the required soft area treatment. The Contractor must allow in the lump sum
tender price for compaction tests as required by the Engineer.
Where fill is to be placed across generally soft or swampy ground, it may not be practical to achieve
compaction of the existing or stripped surface. Where the method of placement of fill across such
area has not been specified elsewhere or shown on the Drawings, and such conditions are encountered,
the Contractor shall notify the Consultant Engineer immediately.
Where fill is to be placed directly onto rock (including undisturbed soapstone), the exposed surface
shall be tined or scarified to a depth of 150 mm minimum and re-compacted with a pad foot roller.
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The Consultant Engineer shall assess the condition and direct the contractor to either excavate and
treat the materials or excavate and replace the materials as appropriate, or use 'Soft Ground'
1.5.4 PLACING FILL BETWEEN UNDER SUB-BASE
Fill material shall be placed in near horizontal layers of uniform thickness deposited systematically
across the fill area. The thickness of each layer should be appropriate for the equipment used, but not
exceeding 200 mm 1oose thickness. At cut to fill junctions, and at the edges of fills, the foundation
shall be excavated or "boxed" so that the minimum thickness of fill to be placed is 100 mm.
The method of excavation, transport and depositing of fill material shall be such that the fill is placed
in as uniform a mixture as practical. Each fill layer thickness should be such that the specified
compaction criteria can be achieved throughout the layer. The Contractor must demonstrate at the
Contractors cost that the specified compaction criteria are achieved using an approved supplier to
perform compaction tests. Tests are to be representative of a specific layer in a specific location. Any
failure of test results will result in the reworking of fill back to a point at which a successful
compaction test result was achieved at the Contractor’s cost.
Before any loose layer of fill is compacted, the material and its moisture condition should be as
uniform as practicable throughout its depth.
The maximum particle size of any rocks or other lumps within the layer after compaction should not
exceed 100 mm.
If there is a delay in the placement of subsequent layers, previously accepted layers which have wetted
up or dried out, shall be tined, moisture conditioned and again compacted to the requirements of this
Specification.
Where fill is to be placed over wet or boggy areas, a heavy grade non-woven geotextile such as Bidim
A34 or equivalent shall be placed directly onto the prepared foundation. The Contractor shall include
in his lump sum tender price all costs associated with the supply and installation of the geotextile.
1.5.5 FILL MOISTURE CONTROL
Material to be used as fill shall be moisture conditioned as required to permit it to be compacted to
the criteria specified. Fill shall not be compacted at moisture content outside the limit of 5% of the
Standard Optimum Moisture Content (AS 1298.E1.1) without approval from the Consultant Engineer.
If the moisture content of the fill falls below the specified minimum, water should be added either on
the fill or in the cut/borrow areas before it is transported to the fill area. Water applied to the fill
should be finely sprayed and uniformly blended throughout the full depth of uncompacted material.
If the moisture content of the uncompacted fill is non-uniform, the material should be mixed to
provide a consistent moisture distribution. Care is needed to ensure that mixing or blending does not
produce segregation of the fill material.
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If the moisture content of material is above the specified maximum, drying of the material may be
accelerated by aeration or by blending with dry materials.
If rain is threatening or the site is to be left unattended, the surface of the fill shall be sealed with
rubber-tire or smooth-wheeled plant and graded to prevent ponding.
1.5.6 FILL COMPACTION
Each layer of fill shall be compacted as a systematic construction operation, using plant which is
specifically assigned to be compaction task and which tracks progressively across the surface of the
fill.
Fill batter faces shall be compacted as a separate operation, or alternatively overfilled and cut back.
The trimmed and compacted batter face should have a roughened surface.
Where compaction control testing shows the relative compaction of the fill to be below the specified
level, all material represented by the test or tests shall be further compacted to exceed the minimum
compaction requirements as confirmed by further testing, or be re-worked and then retested. The
Contractor will test the fill as required by the Engineer at the Contractor’s cost.
The surfaces of all fill layers shall be shaped to provide drainage and to prevent ponding which will
cause deterioration of previously compacted fill layers.
1.5.7 COMPACTION CRITERIA
Fill shall be compacted to a minimum dry density ratio of 98% Standard Proctor (AS1289.El.l) unless
otherwise specified, or shown on the Drawings. Testing shall be undertaken by the Contractor as
required by the Engineer, in accordance with the guidelines presented in AS3798, to confirm that the
fill has been compacted to these specified minimum criteria.
The achieved compaction may also be checked using a dynamic cone penetrometer (AS1289.F3.2),
but this will only be undertaken after a correlation between dry density ratio and penetration resistance
has been established for the particular site and for each of the typical materials encountered. Where a
dispute exists as to the achieved compaction, the results of direct measurements of dry density ration
(AS1289.E4 1) shall be deemed to apply.
The upper layer of filling immediately below road sub-grade level shall be compacted to a minimum
dry density ratio of 98% Standard Proctor. This may be carried out at the time of pavement
construction. The Contractor must allow in the lump sum tender price for compaction tests as required
by the Engineer.
All fill layers have to be compacted, tested and approved by the Engineer prior to filling upper
subsequent layers. Contractor to allow compaction testing at a rate of 1 test per 100m2 (10x10m grid).
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2. PAVEMENT SUB-BASE
2.1 GENERAL
Base & Sub-Base Course are deemed to include supply, placing and compaction, trimming and
grading, and all preparation and maintenance up to sealing of the surface.
Before any Sub-Base Course laying commences the Contractor shall notify the Consultant Engineer
to inspect the sub-grade, as well as being tested by an independent soil Consultant (allowed for in the
Schedule). After approval by the Consultant Engineer, the Contractor may commence placing Sub-
Base Course.
Tests to check compliance with specification requirements shall be carried out on representative
samples of the aggregate selected from any portion of a stockpile or truck load. The size of a
representative sample shall be such that it shall weigh at least 25kg. The test results shall be submitted
to the Consultant Engineer for approval not less than 20 working days prior to use of the proposed
sub-base course materials.
2.2 MATERIALS
2.2.1 DESCRIPTION
This section covers the requirements for natural gravels, crushed gravels, sand, soft or ripped rock
and crushed rock including mixtures thereof for use as pavement base and sub-base. The
requirements relate to the properties of the product as supplied.
2.2.2 DEFINITIONS
(a) Natural Gravel
Gravel is a naturally occurring mixture of angular or rounded rock fragments substantially
retained on a 4.75mm AS sieve with or without finer material and all passing the 75mm AS
sieve. It includes gravels screened to remove oversize fragments.
(b) Crushed Gravels
Crushed gravel is natural gravel, normally river gravel which is crushed to provide close
tolerances on grading.
(c) Sand
Sand is a product of rock weathering substantially passing a 4.75mm AS sieve and is
generally siliceous and free from appreciable quantities of clay and silt.
(d) Soft or Ripped Rock
Soft or ripped rock is rock extracted from a deposit without blasting and not requiring
processing through a crusher for reduction in size.
(e) Crushed Rock
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Crushed rock consists of crushed rock fragments manufactured from hard rock spalls which
are won by ripping or blasting from a solid rock face.
2.2.3 EXTRACTION
The quarry or pit shall be worked in such a way as to ensure that unsuitable material is not included
in the material supplied.
For production of base course crushed rock both the primary and secondary crushers shall be provided
with scalping screens to ensure that any remaining overburden is removed from material supplied to
the crushers.
2.2.4 SOURCE ROCK
Sedimentary source rock shall not be used for production of crushed rock base course material.
Igneous of metamorphic rock shall have a Los Angeles Abrasion Loss complying with the relevant
requirements of Table 2.2.1.
Table 2.2.1
ROCK TYPE LOS ANGELES ABRASION LOSS
(MAX0
BASE SUB-BASE
Granite 40 45
Granodiorite 40 45
Basaltic Rocks 30 35
Hornfels 25 25
Quartzite 30 35
If a source rock is to be used other than the type listed above, the Consultant Engineer will determine
whether the rock type is acceptable and will set appropriate limits
Source rock which does not comply with the specified requirements but from which crushed rock of
satisfactory performance has been produced, may be accepted for use subject to the written approval
of the Consultant Engineer.
2.2.5 PRODUCT
Pavement materials shall be free from vegetable matter, lumps or balls of clay or other deleterious
matter.
Natural gravels, sands and soft or ripped rock shall comply with the requirements of Table 2.2.2
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Table 2.2.2
PROPERTY BASE SUB-BASE
Liquid Limit % (Max)
Plasticity Index (Min)
(Max)
California Bearing Ratio % (Min)
Texas Ball Mill
35
2*
8*
60
45
40
2
12
25
-
* For unsealed pavements the minimum PI shall be 4 and maximum 10.
For crushed gravels and crushed rock the product shall comply with the properties shown in Table 2.2.3.
Table 2.2.3
PROPERTY BASE SUB-BASE
Sand Equivalent 45sec (Min)
Liquid Limit (% Max)
Plasticity Index (Max)
California Bearing Ratio % (Min)
50
30
6*
60
-
40
12
25
*For unsealed pavements the minimum PI shall be 4 and maximum 10.
For gravels, sands and soft or ripped rock, the product grading shall comply with the broad
requirements shown in Table 2.2.4. The Consultant Engineer shall provide a set of detailed grading
limits. Material supplied shall conform with these grading limits.
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Table 2.2.4
SIEVE SIZE AS MM % Passing by Mass
BASE SUB-BASE
150
75
37.5
2.36
0.075
100
100
98
15-40
2-12
100
95
-
12-45
2-10
For crushed gravels and crushed rock the product grading shall comply with the requirements shown in
Table 2.2.5 and 2.2.6.
Table 2.2.5 - Grading Requirements for Crushed 20mm and 40mm Base
SIEVE SIZE MM 20MM BASE 40MM BASE
TARGET
GRADING
LIMITS OF
GRADING
% PASSING
TARGET
GRADING
LIMITS OF
GRADING
% PASSING
37.5
26.5
19.0
9.5
4.75
2.36
0.425
0.075
-
100
100
73
54
38
16
4
-
-
95-100
63-83
44-64
29-48
12-21
1-7
100
85
74
54
39
28
11
3
95-100
80- 90
66- 82
44- 64
29- 49
22- 35
8- 13
2- 5
Table 2.2.6 - Grading Requirements for Crushed Sub-Base
SIEVE SIZE AS MM
LIMITS OF GRADING - %
PASSING
NOMINAL SIZE MM
50 40
75.0
53.0
19.0
0.425
0.075
100
-
54-75
7-21
2-10
-
100
64-90
7-13
2-12
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The crushed rock shall not be graded from near the coarse limit on one sieve to near the fine limit on the
following sieve or vice versa.
2.2.6 WATER
Where it is specified that water is to be added to the material prior to delivery, such water shall be clear
and substantially free from detrimental impurities such as oils, salts, acids, alkalis and vegetable
substances.
2.3 CONFORMITY WITH DRAWINGS
Base and sub-base pavement courses, each consisting of one or more layers, shall be finished to
reasonably smooth and uniform surfaces and after compaction shall conform within the following limits
to the levels, lines, grades, thicknesses and cross sections shown on the drawings or specified or directed
by the Consultant Engineer.
(a) Level
The level of the top of each pavement course shall not differ from the specified level by more
than 5 mm.
(b) Thickness
The thickness of the sub-base course at any point shall be not less than the specified thickness
by more than 5 mm and where the sub-base consists of two or more layers the thickness of
the top layer at any point shall be not less than that specified by more than 5mm.
(c) Shape
No point on the surface of each layer of base or sub-base shall lie more than 6 mm below a
3m straight-edge.
2.4 SPREADING
Spreading shall include running material from delivery vehicles and, as necessary, breaking to size,
mixing and watering to produce material of uniform appearance in the roadbed.
Each layer shall be spread and compacted as soon as practical after the previous layer has been
compacted and has been approved by the Consultant Engineer. The previous layer shall be kept in
good condition during spreading of the layer. Until compaction has been completed and approval has
been given, no further material shall be spread.
Soft or ripped rock shall be broken to a size not exceeding 60 mm and the layer brought to shape
before compaction begins.
Care shall be taken to minimize segregation of material. If segregation occurs the segregated material
shall be mixed and re-spread.
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Unless otherwise specified or shown on the drawings, the compacted thickness of any layer of any
course shall not exceed 150 mm.
Sub-Base and Base Course shall be compacted to 98% of Standard Proctor MDD.
2.5 TEST ROLLING
Pavement layers shall be compacted so that they are capable of withstanding, without visible
deformation or springing, test rolling with either a smooth wheeled roller of mass not less than 12
tonnes and with a load intensity on the rear wheels of not less than 6 tonnes per metre of width or a
pneumatic tyred roller having tyres inflated to 700 kPa and being loaded to not less than 4.5 tonnes
per tyre.
Test rolling shall be carried out to the approval of the Consultant Engineer prior to the placing of the next
layer of pavement material. The final layer should be test rolled immediately following completion of
compaction, but if test rolled at some later date, the entire surface shall be watered and given not less than
eight coverages of the testing roller before the test rolling commences.
Prior to sealing if required by the Consultant Engineer, the pavement strength shall be further checked
by means of defection tests using Benkleman Beam and to PWD requirements. Cost for these tests
is allowed for under the Provisional Sum in the Schedule of Prices. The Contractor must allow in the
lump sum tender price for compaction tests as required by the Engineer.
2.6 PROTECTION OF COMPACTED LAYERS
The surface of any compacted layer shall be kept sufficiently moist to maintain approximately the
appropriate optimum moisture content in that layer until succeeding layer is placed or until any
subsequent pavement works are commenced. Except where a pavement is being constructed under
traffic, construction or other traffic shall not use a compacted layer of pavement without that approval of
the Consultant Engineer. The pavement shall be kept in good order and condition by grading and rolling
and kept free of contamination.
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3. STORMWATER DRAINS
3.1 SCOPE
This specification covers the materials to be supplied and the work to be done in the construction of
stormwater drains. The work comprises the construction of stormwater manholes, culverts, precast invert
drains, rocklining, headwall and outfall structures.
LOCAL / NATIONAL AUTHORITY APPROVALS: The contractor is responsible for liaison with
local / national authorities to secure appropriate permits and approvals for construction of new
drainage works.
Any proposal by the Contractor to use alternative materials or manufacturers to that specified or
previously approved shall be accompanied, as a minimum, by a sample, relevant technical
documentation and test data to substantiate its suitability. Alternative materials or a change in the
source of supply of prime materials shall not be incorporated into the Works without the Consulting
Engineer’s written agreement.
AS 1460 Fittings for use with polyethylene pipes
AS 2033 Installation of polyethylene pipe systems
AS 4130 (Int) PE Pipes, pressure applications
AS 4131 (Int) PE Pipe compounds
BS 2494 Elastomeric joint rings for pipework and pipelines.
BS 8301 Building drainage.
BS EN295 Vitrified clay pipes and fittings and pipe joints for drains and sewers
NZS 3107 Precast concrete drainage and pressure pipes
NZS 3108 Concrete production - ordinary grade
NZS 3302 Ceramic pipes, fittings and joints
NZS 4404 Urban Land Subdivision
NZS 4452 Construction of underground pipe sewers and drains
Department of Labour, Occupational Safety and Health Service - Approved Code of Practice for
Safety in Excavation and Shafts for Foundations.
DOCUMENTS LISTED above and cited in the following clauses are part of this specification and
are the latest edition, including amendments at the time of tender. However this specification takes
precedence when it is of a higher standard than the cited document.
DRAINLAYER QUALIFICATION: Carry out all drainage with competent experienced tradesmen
under the direct supervision of a drain layer registered or licensed under the appropriate National
regulations acts or statutes.
3.2 PIPES
UPVC: UPVC pipes and fittings to NZS 7648.
CONCRETE: Precast concrete to NZS 3107.
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JOINTS: Flexible spigot and socket joints to BS 2494.
3.3 COMPONENTS - CESSPITS, MANHOLES
CESSPITS AND SURFACE WATER SUMPS: Precast concrete complete with lift-up cast iron grate
and frame.
MANHOLES: Circular precast components.
3.4 MATERIALS
3.4.1 PIPES & PRECAST REINFORCED OPEN CONCRETE BOX CULVERTS INCLUDING
ACO DRAINS
Pipes shall be flush jointed reinforced concrete, and shall comply with AS 1342 or equivalent, to the
Classes.
Precast reinforced concrete open box culverts up to 1200mm x 900mm shall comply with the
requirements of AS 1597 Part 1 including ACO Drains.
Any materials shall be first class quality and any defective materials shall be removed from site.
3.4.2 CONCRETE
Concrete used on the work shall be manufactured in accordance with NZS 1900 Chapter 9, 3A:1970
including all amendments and revisions.
Concrete used for encasing and capping culverts, open drains, headwalls and outfall structures shall
be ordinary grade concrete. Minimum strength shall be 25MPa for manholes, slab and similar
structures and 17.5MPa for scour stop.
Concrete supplied from recognized pre-mix concrete suppliers may be used but delivery dockets
which shall show the grade of concrete and its certified strength shall be retained and produced if the
Consultant Engineer calls for same.
3.4.3 CEMENT
Cement used for site mixed concrete, mortar and lean mix bedding and haunching shall comply with
NZS 3172:1974 for Portland cement. It shall be stored in a damp-proof shed. Any cement that is
lumpy or affected by moisture must be removed from the site.
3.4.4 REINFORCING RODS
Shall be of clean, deformed, round mild steel complying with NZS 3402P:1973.
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3.4.5 MORTAR
Shall consist of one part cement to two parts sand thoroughly mixed with water to form a paste of a
consistency suitable for the particular purpose. Only freshly made mortar shall be used.
"Reworking" of mortar shall not be permitted and such mortar shall be disposed of.
3.5 CONSTRUCTION OF ALL CAST IN-SITU ITEMS
3.5.1 PLACING CONCRETE
The concrete shall be worked with suitable tools when placed in the boxing to ensure maximum
density and a smooth surface without form marks. The segregation of the larger stones shall be
prevented by spading out the concrete to a flat slope. Any honeycomb or defects appearing on the
surface shall be remedied as directed by the Consultant Engineer immediately the boxing is removed.
Only freshly mixed concrete shall be used. Special attention shall be given to this point especially in
warm weather, when the setting of cement is considerably accelerated. Any concrete which shows
signs of initial setting will be condemned and shall be removed from the site of the work immediately.
Under no circumstances shall more than twenty minutes elapse between the time of mixing and
the time of placing or using of the concrete. Retempering of concrete, that is, mixing with water after
it has partially set, will not be permitted.
3.5.2 BOXING
Approved steel forms and moulds may be used in lieu of timber boxing. Timber for boxing where
supporting exposed surface shall be thickened and dressed smooth on one surface and both edges and
the boxing when built shall be close jointed and grout tight. It shall be designed to be easily removable
without marring the green concrete. It shall be designed to be securely stayed to prevent displacement
and appreciable deflection. Before being used again all boxing will be thoroughly cleaned and treated
with soft soap or other approved material to prevent the concrete adhering. The boxing supporting
vertical faces shall not be removed for at least thirty six hours after the concrete is placed. The green
concrete shall be protected by a covering of damp sacks for at least a week after the concrete is placed.
3.6 EXCAVATION AND BACKFILLING
3.6.1 EXCAVATION
The excavation for the trenches shall be taken out in accordance with the longitudinal sections and
by open cut. The trench shall be of sufficient width to admit all operations necessary for the jointing
of pipes and placing of concrete to be carried out with freedom.
The sides, where necessary and required by law, shall be supported by suitable shoring placed so that
it shall not interfere with the work of pipe laying and jointing and concrete work.
The Contractor shall observe the provision of the "Construction Act 1959" and any amendments
which may be made thereto and section 1.16 of this specification.
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3.6.2 BACKFILLING
All pipes shall bear evenly on the bedding along the whole length of the barrel. No backfilling shall
commence until the pipes have been inspected and passed. The first layer of backfilling shall compose
clean stone-free soil, and extend to 150mm over the top of the pipe and shall be thoroughly
compacted, except where pipes are concrete capped or encased.
3.6.3 SUBSOIL WATER
Should subsoil water appear in the trenches it must be kept down below the level of the bottom of the
concrete or the joints, until the concrete is thoroughly set. For this purpose the Contractor shall
provide and use in the work all necessary pumping facilities, so positioned that they do not interfere
with the bedding, laying or jointing the pipes. All costs, whatsoever, in connection with keeping the
subsoil water down to be borne by the Contractor. Should the Contractor fail to take adequate steps
to keep the water down, or should the Consultant Engineer consider the methods adopted by the
Contractor are endangering or damaging the foundations of the sewers, the Consultant Engineer shall
have the power to order the Contractor to adopt other methods. Under no circumstances shall any
water be allowed to drain into the existing sewers. The Contractor shall not permit any pump to
discharge onto the roadway.
The above will also apply to sea water ingrest. The contractor shall manage his time to work when
the tide is low if the water is unable to be pumped out of the trench.
3.7 PIPE LAYING PROCEDURE
3.7.1 BEDDING
Pipes shall be laid on clean sand or other approved granule material. Bedding layer shall be 200mm
minimum under the pipe barrel and sockets.
Precast slabs shall be laid on a 50 mm thick bed of concrete of minimum strength 15MPa. The
concrete bed shall be formed on top of a clean and even surface, any weak areas shall be removed
and replaced by clean fill and properly compacted as directed by the Consultant Engineer.
3.7.2 LAYING
Only competent approved drain layers will be allowed to lay the pipes which must be laid with the
greatest possible accuracy as to line and levels. Proper sight bars and boning rods shall be used for
this purpose.Pipes shall be laid at the low end and proceed upstream unless permitted by the
Consultant Engineer. No pipe laying or bedding shall be commenced until the trench foundations
have been inspected and passed by the Consultant Engineer.
Should the Contractor excavate to a greater depth than required, such space must be filled with
basecourse material at the Contractor's expense. Trenching and bedding must be done in at least 4m
lengths, and the bedding well banked up the sides as shown on the detail drawings.
All joints shall be mortared in watertight fashion on inside and outside faces.
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3.7.3 TESTING OF STORMWATER PIPES
All pipes will be inspected by means of a mirror and lamp to ensure correctness of line and grade.
Before backfilling the Consultant Engineer will inspect all joints and bedding.
Should there be any length or lengths of pipes which are not laid to the satisfaction of the Consultant
Engineer, notwithstanding that such may have already been inspected, such portions must be taken
up and re-laid and the cost of making good any damage done by breakages or otherwise in so doing
must be borne by the Contractor.
3.8 HEADWALLS AND OUTFALL STRUCTURES
Where headwalls and outfall structures in mass or reinforced concrete are required the concrete,
formwork etc, shall conform to the provision of Section 9 of this Specification.
3.8.1 EXCAVATION
General
All drains shall be excavated to the grades and levels shown on the Consultant Engineering Drawings.
Drains must be constructed so as to effectively collect surface water off roads and properties.
Drains
Drains, where shown on the drawings, shall have concrete invert units and rock pitched sides. Except
where excavated in in-situ soapstone the rock pitching shall be installed to 150mm lower than existing
or finished ground level.
Drains shall be excavated to the profile shown on the Drawings. Any over excavation shall be made
good, to the Consultant Engineer's satisfaction, at the Contractor's cost.
3.8.2 LAYING
Precast Concrete ACO Drains
Refer to manufacturers requirements. ACO drains shall be laid true to level and grade and jointed as
detailed. The units must be supported for their full length and not span between concrete joints.
The gap between units shall not exceed 50mm and the concrete bank shall be placed so as to ensure
optimum penetration of concrete. The jointing concrete must be fully cured before water is permitted to
flow through the drains.
Any over-excavation beneath the inverts shall be made up with compaction, approved granular material
- or lean mix concrete - at the Contractor's expense.
Stone Pitching
Stone pitching is required for drain lining, at culvert entrances and exists, at changes of direction of drains
and for outfalls.
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Wherever used, the individual stones must be thoroughly bedded in concrete or mortar. The exposed
surface must be as smooth as possible to allow good flow conditions.
The practice of dry packing and pointing rocks is not acceptable.
50mm dia uPVC weepholes must be provided for every 1m2 facing of all stone pitching and located
immediately above the top of the pre-cast invert. These holes should be staggered where necessary.
Stormwater Manholes
Concrete formwork and reinforcing shall comply with Section 9 of this Specification.
Pipes shall be carefully cast into the walls of the pits at the correct levels and in a watertight fashion. The
bottom shall be carefully shaped to ensure complete discharge of water.
3.9 DRAINAGE TRENCHES AT BASE OF RETAINING WALLS
3.9.1 DRAINAGE TRENCH:
The drainage trench shall be sufficiently deep that the top of the pipe will be not less than 0.45m
below the top of the trench and shall be not wider than 0.6m. The base of the trench shall be
constructed so that there is a uniform fall 1:`150, without apparent high or low areas which may
impede the efficient drainage of collected water.
3.9.2 DRAINAGE PIPE
The drainage pipe shall be an approved flexible slotted PVC pipe of 100 mm.
Joins in the pipe shall be made in accordance with the manufacturers recommendations and be such
that an unimpeded flow of water can occur through the joins. The joins shall be wrapped in an
approved non -woven geotextile.
3.9.3 TRENCH BACKFILL
Trench backfill shall comprise crushed rock or run of pit river gravel, containing not more than 5%
dry weight of material finer than 0.075 mm, and generally be uniformly graded with particle sizes
between 5 mm to l5rnm. The maximum particle size up to 150 mm above the pipe shall be 10 mm.
The balance of the backfill may have a maximum particle size of up to 25 mm.
A 25 kg sample of each of the proposed trench backfill materials shall be submitted to the Consultant
Engineer for approval not less than l0 working days before it is planned to place trench backfill.
Stockpiling or use of any material on site before this approval is given will be entirely at the
Contractor's risk. After approval is given for the use of a particular material, the Contractor shall
ensure all material delivered conforms to the general particle size distribution and quality of the
sample submitted for approval. The Consultant Engineer may undertake checks on material being
delivered to assess conformance with the approved sample(s).
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3.9.4 CONSTRUCTION
Crushed rock or run of pit gravel shall be wrapped with filter fabric. The filter fabric shall be Bidum
A24 or equivalent unless otherwise noted on the drawings.
A bedding layer not more than 25 mm thick of 10 mm maximum size trench backfill material shall
be placed in the base of the trench. The drainage pipe shall then be placed on this initial layer joined
as required, and carefully covered with further backfill to achieve a minimum cover of 10 mm over
the pipe. This layer shall then be lightly compacted taking care not to damage the pipe. The balance
of the backfill may then be placed in the layers nor greater than 300 mm loose thickness and
compacted. The trench backfill material should extend not less than 150 mm above the top of the
trench, over a width equal to twice the width of the trench. Filter fabric shall cover the top of the
trench backfill with a 200 mm minimum overlap.
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4. CONCRETE, FORMWORK AND REINFORCEMENT
FOR PAVEMENT
4.1 SCOPE
This chapter is a general specification only. More specific details are included within the descriptions of
each major unit of construction elsewhere in this specification.
4.2 MATERIALS
The specification shall be read together with the following New Zealand Standard Specifications:
a) NZS 3122:1974 Portland Cement (ordinary and rapid hardening)
b) NZS 3112:1974 Methods for Testing of Concrete
c) NZS 3111 & 3121 Concrete Materials and Methods of Test
d) NZS 3101 Reinforced Concrete Design
e) NZS 1900 Chapter 9, Division 9-3A Concrete
If ready mixed concrete is used, the handbook of the New Zealand Ready Mixed Concrete Association
Inc., for the Grading Scheme Covering Classification of Plants, shall also be read with this specification.
Items in the Schedule of Prices allow for the building-in to concrete of various components. However,
these items are not limiting and the Contractor shall ensure that all components necessary are built into
the concrete.
Materials shall be water and aggregate to NZS 3111, and 3121, with maximum stone size of coarse
aggregate of 20mm and ordinary Portland cement to NZS 3122.
All concrete shall comply (as a minimum standard) with the requirements for High Grade Concrete -
Clause 9.3A17 of NZS 1900.
Minimum cement content = 360 Kf/m3
Maximum water/cement ratio = 0.52 by weight
Note: Some variation of these proportions may be considered by the Consultant Engineer provided
evidence is produced in support of such variation and is to the satisfaction of the Consultant Engineer.
Workability of the concrete density and the ability to take a high surface finish as well as strength are all
factors of significance for concrete incorporated in the works of this contract.
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With a view to limiting shrinkage particularly in floor slabs, concrete mixed to the requirements of
Special Grade Concrete - Clause 9.3A18.1 NZS 1900 (which permits the use of less cement and hence,
for the same workability and strength, less water) is preferred.
Concrete used (except site concrete) shall attain a 30MPa crushing strength based on a standard 300mm
x 160mm cylinder at 28 days unless otherwise specified.
It is preferred that all concrete is produced by a ready mix plant, and it is further preferred that this plant
has a Special Grading in terms of the N.Z.R.M.C.A Grading Scheme. The Consultant Engineer at his
discretion may not accept any concrete produced by an ungraded ready mix plant. Alternatively, an
approved weigh batching plant may be established on the site and operated (as a minimum standard) to
the requirements of Clause 9.3A.17 NZS 1900. In this case, mixers shall comply with the requirements
of the NZS 3105, Batch Type Concrete mixers.
Records shall be kept and tests taken as specified in the Grading Scheme and NZS 1900 and these results
shall be kept and made available to the Consultant Engineer as required. The Consultant Engineer shall
require certificates of test from a competent authority for all concrete materials before manufacture
commences and may require additional tests from time to time as the work proceeds. In addition to the
minimum number of compression tests required in both Clause 7(c) of the Grading Scheme (i.e. two sets
per day or one set every forty batches), the Consultant Engineer may require further compression tests
to be carried out.
The cost of carrying out all routine and control testing and preparing all records and of producing initial
test certificates for all materials shall be borne by the Contractor and he shall allow for such costs. Tests
on concrete shall be conducted in accordance with NZS 3112. Methods for the Testing of Concrete, and
tests on cement and aggregate shall be in accordance with the appropriate specification.
The plastic concrete shall be sufficiently workable to permit placing and compacting by methods to be
approved (appropriate to the various situation in the works) so that the hardened concrete is dense and
has the required surface finish. Good workability shall, as much as possible, be achieved without the
excessive use of water.
Excessive bleeding of the placed concrete must also be prevented.
No admixtures of any kind, including air entraining agents and pozolans shall be used without the written
permission of the Consultant Engineer. Their use, although not favored, will, however, be considered at
the Contractor's expense. Mixing shall be carried out in accordance with the requirements of the Grading
Scheme (for central or transit mixers) and NZS 1900.
Concrete shall be handled and placed in accordance with Clauses 9.3 A.20, 9.3 A.28, and A.29, of NZS
1900.
The Contractor shall advise the Consultant Engineer in advance of the methods he proposes to employ
to place concrete in the various parts of the work. The Contractor shall decide before tendering, by
inspecting the site and drawings, methods he shall employ for placing concrete in the various situations
and shall allow for this in his scheduled rates for concrete. Segregation of concrete during placement
will be cause for rejection of the method by the Consultant Engineer and the cessation of operations.
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Transporting and placing plastic concrete by means of pumping techniques will be accepted as a method
of placing provided approved equipment is employed and all other criteria in respect of concrete strength,
mix design, placing, density, finish etc., are met.
All concrete shall be thoroughly compacted during and immediately after depositing, by means of
approved power driven vibrators of size suitable for the section being poured.
Frequencies under load shall range between 4,000 and 8,000 cycles per minute, depending on the unit
used which should normally be of the "internal" or "spud" type. The use of a vibrating screed may be
considered for slabs.
Operators shall be competent and dependable.
Vibrations shall not be used to produce lateral motion of concrete but shall be concentrated in causing
vertical settlement and consolidation. Care shall be observed to ensure that zones of vibration overlap
and that no portions are missed. Vibrating elements in continuous operation shall be slowly inserted and
withdrawn from the concrete mass at distances apart not exceeding 600mm or the radius over which
vibration is visibly effective.
Vibration shall not be transmitted through boxing or reinforcing to concrete which has taken its initial
set. The vibrating element shall be used in such a way as not to displace reinforcing steel or damage the
internal faces of boxing by contact therewith. Vibration shall be continued until the concrete becomes
uniformly plastic, an indication of this being the appearance of a visible line of cement paste at the
junction of the concrete with forms and reinforcing steel, or the forming of a level top surface with just
enough mortar for finishing.
The vibrating head shall be removed from the concrete when this stage is reached.
The formation of pools of grout or areas of segregation by over-abrasion will not be permitted. Removal
of vibrating tools shall be made slowly to prevent the formation of voids. The formation of air bubbles
against vertical formwork or faces sloping back towards the concrete shall be obviated by lightly
vibrating as closely as possible to the forms without damaging them, supplemented by the use of hand
spading and slicing tools along the forms.
A spare vibrator must be available at all times when concreting.
Where a placing diagram is included in the drawings, construction joints shall be located only where
indicated. In the absence of a placing diagram, construction joints shall be located only where directed
or approved by the Consultant Engineer.
In general, construction joints shall be avoided as much as possible.
Wherever practicable, each particular part of the structure shall be concreted in one continuous operation.
Construction joints shall be formed as shown on the drawings or where not specifically detailed shall be
perpendicular to the axis of the member.
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Joints shall be formed perpendicular to the finished faces of the structure and feather-edges avoided,
unless detailed otherwise.
Vertical or stepped joints shall be properly boxed with close fitting formwork. At the horizontal joints
on exposed faces, temporary beading shall be fixed inside the forms to ensure straight lines on the outer
edges of the joints.
Immediately prior to concreting forms shall be re-tightened near construction joints to prevent mortar
escaping and flowing over the faces of preceding lifts of concrete.
Horizontal and vertical construction joints shall only be made where necessary and where approved by
the Consultant Engineer. All horizontal and vertical construction joints shall be provided in the following
fashion.
Horizontal: Bring the concrete surface to a level, horizontal line and vibrate carefully, apply an
appropriate retarding agent to the concrete surface while still wet and hose off the following day to
produce a dense, exposed aggregate surface.
Vertical: Apply an appropriate retarding agent to the stop-end formwork immediately, or as soon as
possible before placing the concrete. Remove the stop-end the following day and expose the aggregate
on the concrete face by jetting with water.
In general, no further treatment will be required on construction joints, but in specific instances provision
of a water stop section may be required.
At the time of placing concrete against construction joints, the joint shall be thoroughly damp but without
free water. It will not be satisfactory simply to wet dry concrete immediately prior to concreting.
Curing shall be in accordance with Clause 9.3 A.28.9 NZS 1900 and curing membrane compounds shall
not be used. In hot weather, concrete (particularly slabs) shall be covered as soon as possible after
hardening and kept wet. Provision must be made for keeping concrete wet in weekends and outside
normal working hours.
4.3 FORMWORK
The Contractor shall allow in his prices for those items all associated materials and work involved, such
as falsework and erection, cleaning, coating and dismantling and any other materials or work necessary.
All formwork shall be in accordance with Clause 9.3 A.31 NZS 1900 and shall be constructed in such a
manner and of suitable materials to ensure the production of the surface finish specified. Only approved
ties and spacers shall be used on wall forms.
Forms shall be designed so that the deflection of sheathing shall not exceed 1/200 of the span between
joists or other supports and in any case shall not exceed 3mm.
The methods of construction shall be such that vertical surfaces can be stripped without disturbing the
boxing or supports to beam, slab, or arch soffits, which require to be left in place for a longer period.
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Forms for high sections such as walls shall have one side left open, which shall be closed progressively
as concreting advances, but at no stage to a height exceeding 1.200m above the layer of concrete being
placed.
Forms shall be filleted or chamfered at all sharp corners, and shall be given a slight bevel at all projections
to ensure easy removal without damage to the concrete.
Bolts, and other metal fittings used in formwork erection, shall be constructed so as to permit their easy
removal to a depth of at least 50mm from the face without injury to the concrete and so that upon their
removal the cavities left are of the smallest possible size. Forms may be re-used, subject to the approval
of the Consultant Engineer, and provided they still satisfy the above requirements.
Surface of re-used forms which are to come in contact with concrete shall be thoroughly cleaned before
erection.
The inside surface of all forms shall be given a coat of approved material which shall not stain or adhere
to the concrete, or shall be saturated with water immediately before placing the concrete.
4.4 SURFACE FINISH
Surface finish of all surfaces both formed and unformed, interior and exterior must be of a uniform high
standard. Acceptable standards will be determined on test panels produced by the Contractor at the
commencement of the work. Reference should be made to the NZ Portland Cement Association
Publication A.C. 4 extracts from which have been included hereunder. The surface finish required for
all surfaces is shown on the drawing as a reference defined hereunder.
a) Unformed Surfaces
All surfaces formed without the use of formwork, e.g. floor slabs and pad and beam tops. The
reference to the standard of finish is prefixed by the letter U.
b) Formed Surfaces
Those resulting from the placing of concrete against formwork, e.g. walls, columns, upstands,
slabs, etc. In this case the reference is prefixed by the letter F.
c) Wood Flat Finish
Concrete floated after screeding but not until some stiffening has taken place in the surface of
the concrete and the moisture film has disappeared. Floating should work the concrete no more
than is necessary to produce a surface that is uniform in texture and free from screed marks.
d) Steel Trowelled
Finish U3
After placing concrete the surface is screeded flat and (when the moisture film has disappeared,
and the concrete hardened enough to prevent an excess of fine material and water from being
worked in the surface) trowelled by hand or by power driven machine.
e) Hard Steel Trowelled
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Finish U3
As above but with further trowelling when the surface is nearly hardened, using firm pressure
and trowelling until the surface is hard and has almost a glossy appearance.
NOTE:
Hair cracks and crazing are usually a result of a concentration of water and fines on the surface caused
by excessive trowelling before sufficient stiffening has taken place on the surface. Such cracking is
aggravated by too rapid drying or sudden cooling and care must be taken to avoid these effects.
f) Finish F1
Some surface roughness allowed, e.g. slight joint displacement, form marks, etc. Formwork
may be constructed of any material that will not leak mortar. Form tie holes must be filled.
g) Finish F2
Formwork must be of tongue and groove, dressed timber, plywood, steel or hardboard faced and
all joints must be grout tight. Treatment of surface after removal of forms includes filling all tie
holes and rubbing down fins and roughness.
h) Finish F3
Formwork as above, but must be skillfully fitted. All forms must be grout tight and joints must
be sealed with suitable sealing strips or compound. Surface treatment shall include removal of
any fins, filling of all tie holes and surface air holes to leave a surface which is smooth, true and
dense which will not offer any pockets or ledges where dirt and dust may accumulate.
Maximum Allowance of Irregularities in Concrete Surfaces
Unformed surfaces - measured from 3.0m template.
U2 6mm deviation
U3 and U3H 6mm deviation
Formed surfaces measured from a 1.5m template.
F1 25mm gradual deviation 12mm abrupt deviation
F2 12mm gradual deviation 6mm abrupt deviation
F3 6mm gradual deviation 3mm abrupt deviation
"Abrupt deviation" means offsets, etc., caused by displacement or misplacement of misplaced formwork.
"Gradual deviation" includes all other.
NOTE:
Mortar for filling tie holes, etc., shall be made from the same sand as used in the concrete being filled.
The sand must all pass a 5mm N.Z.S. sieve and should be mixed in the proportions one and half to two
parts sand to one part ordinary Portland cement by volume. Tie holes should be filled with a stiff mortar
and compacted by ramming or caulking with a suitable tool. Mortar should be cured for 3 days.
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Surface finishes of the various surfaces shall be as noted on the drawings. As a guide however, typical
finishes will be:
Hidden formed surfaces : F2
Exposed formed surfaces : F3
Most horizontal surfaces : U3
Particular horizontal surfaces : U3H
The Contractor shall allow in his lump sum tender price for achieving the Unformed surface finishes
specified.
4.5 REINFORCEMENT
Reinforcement shall conform tothe requirements of Clause 9.3 A.9 NZS 1900.
All 10mm, 12mm, 16mm, 20mm dia. bars shall be deformed high tensile steel (Grade 500).
Hooks shall only be provided where shown and shall be formed with an internal radius of not less
than that stated in 9.3 A.33.2 of NZS 1900, with a minimum extension beyond the curve of 4 bar
diameters.
Cover from concrete surface to reinforcement shall be accurately maintained as shown on the
drawings. All reinforcing steel shall be accurately placed in position as shown on the plans and during
the pouring and compacting of the concrete, shall be firmly held against displacement.Soft black iron
wire not thinner than 1.2mm nor thicker than 2.0mm shall be used for tying the reinforcing rods at
intersections. Ties shall be located at sufficiently close intervals to maintain the rods in their correct
positions.
Distances from the forms shall be maintained by means of stays, blocks, ties, hangers, or other
approved supports. Blocks for holding reinforcement from contact with the forms shall be clean
precast mortar blocks of approved mixture, shape and dimensions. Reinforcement in any members
shall be placed and then inspected and approved by the Consultant Engineer before the placing of
concrete begins.
Concrete placed in violation of this provision shall be liable to rejection and removal.
Provision shall be made for workmen to reach any part of the work without standing on reinforcement.