AN
SECTION III – CONCRETE
February, 2008
Launceston City Council
General Specifications
Concrete
TABLE OF CONTENTS
SECTION III CONCRETE
3
3.01.00 GENERAL
3
3.01.01
SCOPE
3
3.01.02
INSPECTION
3
3.01.02
STANDARDS
3
3.02.00 TESTING AND ASSESSMENT
3
3.02.01
AUTHORITY AND PERSONNEL
3
3.02.02
SAMPLING AND TESTING
3
3.02.03
ASSESSMENT
4
3.02.04
SURFACE REPAIRS
4
3.03.00 FORMWORK
4
3.03.01
REQUIREMENT
4
3.03.02
FORMWORK TOLERANCES
4
3.03.03
VISUALLY IMPORTANT SURFACES
5
3.03.04
FORMWORK CONSTRUCTION
5
3.04.00 CONCRETE MATERIALS
6
3.04.01
STANDARD
6
3.04.02
READY MIXED SUPPLY
6
3.04.03
SITE MIXED SUPPLY
6
3.04.03
GROUT
6
3.05.00 DESIGN OF MIXES
7
3.05.01
CLASS OF CONCRETE
7
3.05.02
MIX DESIGN AND ACCEPTANCE
7
3.05.03
READY MIX SUPPLY
7
3.06.00 NO-FINES CONCRETE
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February, 2008
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Launceston City Council
General Specifications
Concrete
3.06.01
REQUIREMENT
7
3.06.02
PLACING
7
3.07.00 REINFORCEMENT
8
3.07.01
REQUIREMENT
8
3.07.02
PROTECTIVE COATING
8
3.07.03
FIXING REINFORCEMENT
8
3.07.04
REINFORCEMENT SUPPORTS
8
3.07.05
LAPPING OF REINFORCEMENT
8
3.07.06
CLEANING OF REINFORCEMENT
8
3.08 00 PLACING
9
3.08.01
PLACING AND COMPACTION
9
3.08.02
TEMPERATURE OF CONCRETE
9
3.08.03
CURING AND PROTECTION
9
3.09.00 PRECAST UNITS
10
3.09.01
REQUIREMENTS
10
3.09.02
PRECAST DIMENSIONAL TOLERANCES
10
3.09.03
HANDLING PRECAST UNITS
10
3.10.00 JOINTS
10
3.10.01
CONSTRUCTION JOINTS
10
3.10.02
MOVEMENT JOINTS
10
3.10.03
WATER STOPS
11
3.11.00 PAYMENT
3.11.01
11
PAYMENT
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February, 2008
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Launceston City Council
General Specifications
Concrete
SECTION III CONCRETE
3.01.00 GENERAL
3.01.01 SCOPE
Concrete work generally, including precast concrete, formwork, reinforcement, joints, underlays to
slabs and concrete finishes are specified in this section.
3.01.02 INSPECTION
Give sufficient notice to the Superintendent for inspection of the following:
•
•
•
•
•
Foundation preparation for blinding underlay.
Completed formwork.
Reinforcement.
Placing of concrete.
Preparation of remedial works.
3.01.02 STANDARDS
The following standards are referred to in this section.
AS1012
AS1302
AS1303
AS1304
AS1326
AS1379
AS1510
AS1599
AS3600
AS3610
Methods of Testing Concrete.
Steel Reinforcing Bars for Concrete.
Hand Drawn Steel Reinforcement Wire for Concrete.
Hard Drawn Steel Wire Reinforcing Fabric for Concrete.
Polyethylene Film for Packaging and Allied Purposes.
Ready Mixed Concrete
Code of Practice for Control of Concrete Surfaces
Pressure Sensitive Adhesive Packaging Tapes.
Concrete Structures Code.
Formwork Code.
3.02.00 TESTING AND ASSESSMENT
3.02.01 AUTHORITY AND PERSONNEL
The organisation responsible for testing and assessment of concrete and concrete materials shall be
NATA registered.
For each test, maintain the records and reports of test results as required by AS1012. Make the
records available to the Superintendent on request.
3.02.02 SAMPLING AND TESTING
Sampling and testing to AS1012 Parts 1-3 inclusive. The following minimum number of 300 mm x
150 mm diameter test cylinders shall be tested:
• One sample of 3 cylinders for each 12m3 or part thereof placed in an essentially continuous
manner.
• One cylinder of the three taken shall be tested at 7 days or as directed by the Superintendent.
• The remaining 2 cylinders shall be tested at 28 days.
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Launceston City Council
General Specifications
Concrete
3.02.03 ASSESSMENT
The test results shall be assessed in accordance with AS3600. Should the 28 day cylinder strength
as determined not comply with the specified strength, the Superintendent shall reject the concrete
and direct the Contractor to remove rejected concrete from the site.
Alternatively, approval may be given to the retention of the hardened concrete liable to rejection, on
the basis of:
•
•
•
•
The criteria in AS3600 Clause 19.1.10.3.
An appraisal of the statistical information related to the concrete strength.
Approved remedial work.
Reduction in cost.
3.02.04 SURFACE REPAIRS
Concrete liable to rejection because of surface defects may be in some cases be accepted subject to
the specified exposure classification and the successful repair of the defects. Repairs to concrete
surface shall be performed by skilled workmen.
Repairs of imperfections shall be completed within 24 hours after removal of forms.
Concrete that is honeycombed, fractured and the like, must be removed and replaced with suitable
non shrinkage mortar as directed by the Superintendent.
Holes resulting from the removal of ends of form ties shall be filled with suitable approved type of
non-shrinkage mortar.
Mortar shall not be used for filling behind reinforcement.
3.03.00 FORMWORK
3.03.01 REQUIREMENT
Design and construct formwork and falsework to the approval of the Superintendent so that concrete
when cast in the forms, will have the dimension, shape, and surface finish as required by the
contract.
If formwork fails to meet the requirements of the contract, any concrete which has been cast in that
formwork may be rejected.
If required by the Superintendent, submit formwork or falsework drawings for approval.
3.03.02 FORMWORK TOLERANCES
The finish concrete surfaces shall be within the tolerances stated in the following table:
Formwork
Class To
AS 1510
1
2
3
4
Deviation From
Correct Position
Maximum
Misalignment
Maximum:
Relative:
Between
Pours:
10 mm
15 mm
20 mm
25 mm
1.5 mm
2.5 mm
3.5 mm
4.5 mm
1 mm
2 mm
3 mm
4 mm
Across
Form
Joints:
0 mm
2 mm
2 mm
4 mm
The deviation in beams and slabs shall be measured before the removal of falsework or shoring.
The minimum standard of finishes to formed concrete shall be as follows:
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Launceston City Council
General Specifications
CONCRETE ELEMENT
Concrete
FORMWORK
CLASS:
COLOUR
CONTROL TYPE:
1.
Normal architectural work and
surface not otherwise specified
2
B
2.
Civil engineering works
3
C
3.
Surfaces to be rendered or
hidden by other finishes
4
Not Applicable
4.
Surfaces permanently concealed
(e.g. footings, rear faces of
retaining walls)
5
Not Applicable
5.
Surfaces to be abrasive
blasted, smooth rubbed, sand
floated, grout floated, or
scrubbed
2
A
6.
Surfaces to be brush
hammered or tooled
2
B
3.03.03 VISUALLY IMPORTANT SURFACES
Visually important surfaces include concrete surfaces from AS1510, formwork classes 1, 2 and 3.
Set out formwork to give a regular arrangement of panels, joints, bolt holes, and the like visual
elements in the formed surface.
Unless otherwise specified form a 45o bevel, 25 mm on the face, by chamfering or filleting the forms.
3.03.04 FORMWORK CONSTRUCTION
All forms shall be built mortar-tight and of sufficient rigidity to prevent distortion during construction.
Where forms are re-used, their original shape, strength, rigidity and surface smoothness shall be
maintained at all times.
Before placing reinforcement, all forms shall be treated with a release agent, to the interior surfaces
of the formwork, except where directed by the Superintendent.
Where necessary clean
reinforcement to remove all traces of release agent to the satisfaction of the Superintendent.
If ties used to secure and align the formwork, effective precautions shall be taken to ensure
watertightness after their removal.
The period elapsing between placing concrete and removing formwork shall be as follows:
Walls
Footings
Valve Boxes
Falsework
Section III - Concrete.doc
72 hours
24 hours
24 hours
168 hours
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Launceston City Council
General Specifications
Concrete
3.04.00 CONCRETE MATERIALS
3.04.01 STANDARD
Concrete materials shall comply with AS3600.
Chemical admixtures shall comply with AS1478. Use of the admixture shall be as agreed with the
Superintendent.
Fly ash or blended cement shall not be used without the written approval of the Superintendent.
Maximum aggregate size shall be 20 mm.
3.04.02 READY MIXED SUPPLY
Ready mixed supply shall comply with requirements of AS1379. Concrete shall be delivered in
agitating trucks.
Concrete is liable to be rejected if the elapsed time between the wetting of the mix and the discharge
of the mix at the site exceeds the following:
Concrete Temperature
(oC)
Maximum Elapsed
Time (hr)
10 - 24
24 - 30
30 - 32
2.00
1.50
1.00
Each batch of concrete shall be accompanied with a docket listing all pertinent information regarding
the concrete mix including but not limited to the following:
•
•
•
•
•
The works for which the concrete was ordered.
The total amount of water added to the plant.
The maximum amount of water permitted to be added at site.
Slump achieved and the design slump.
Cement content in the mix.
3.04.03 SITE MIXED SUPPLY
The Contractor must satisfy the Superintendent that the proposed site mixed supply plant is capable
of producing concrete in accordance with the requirements of AS1379. Mixing by hand is not
permitted.
The Contractor shall ensure that an alternative source of supply is readily available at the time of
each pour.
3.04.03 GROUT
Standard to AS3600 Clause 19.1.11. Maximum shrinkage allowable is 1% by volume after 24 hours.
Maximum water cement ratio is 0.45 by weight.
Minimum compressive strength shall be 24 MPa at 7 days and 40 MPa at 28 days.
Epoxy grout shall be of an approved commercial epoxy formulation of high strength.
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Launceston City Council
General Specifications
Concrete
3.05.00 DESIGN OF MIXES
3.05.01 CLASS OF CONCRETE
Concrete shall be classed as "Class X" where X is the minimum 28 day compressive strength in
Megapascals.
The target slump values, maximum water cement ratios and minimum and maximum cement
contents shall be within the following values.
______________________________________________________________
Class of
Minimum
Target Cement Content
Maximum
Concrete
28 day
Slump
Water
Compressive
Cement
Strength
Min.
Max.
Ratio
Mpa
mm
kg/m3 kg/m3
______________________________________________________________
N50
50
50-60
450
520
0.45
N40
40
50-60
400
470
0.45
N30
30
50-75
350
420
0.50
N20
20
50-75
300
380
0.50
Blinding Concrete 170
_____________________________________________________________
3.05.02 MIX DESIGN AND ACCEPTANCE
The Contractor shall be responsible for the design of mixes and for the production of concrete.
The Contractor shall submit for approval, details of the concrete mix proposed.
Not less than 28 days before placing concrete, the Contractor shall prepare trial mixes using the
approved mix design. For each trial mix, the Contractor shall produce at least eight (8) test cylinders.
The cylinders shall be tested as required by the Superintendent.
All costs associated with the production of trial mixes and testing shall be included in the respective
schedule of rates.
3.05.03 READY MIX SUPPLY
If concrete is supplied by an approved supplier of Ready Mixed Concrete, the Superintendent at his
discretion may accept the results of test cylinders cast from identical mixes produced previously by
the supplier.
The information and details of the mix shall nevertheless be supplied.
3.06.00 NO-FINES CONCRETE
3.06.01 REQUIREMENT
No-fines concrete shall consist of cement and coarse aggregate. Coarse aggregate grading shall
conform to AS1465.
The concrete proportion shall be 8 parts of aggregate to 1 part of cement by weight. The water
cement ratio shall be 0.38 - 0.45 by weight.
3.06.02 PLACING
No-fines concrete shall be placed without tamping or vibrating. It shall be moist cured for at least 4
days or as directed by the Superintendent. Sand or other finer material likely to enter the voids shall
not be permitted for curing.
Before structural concrete is poured over no-fines concrete, approved polythene or plastic sheets
shall be placed over the no-fines concrete. Any tears or holes shall be repaired.
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Launceston City Council
General Specifications
Concrete
3.07.00 REINFORCEMENT
3.07.01 REQUIREMENT
The reinforcement shall comply with the standard AS3600 Clause 19.2.
Supply and fix
reinforcement, including the necessary tie wires, support chairs, spacers and the like.
Reinforcement shall be readily identifiable as to the grade and origin.
When requested by the Superintendent, obtain from the manufacturer and furnish a certificate of
compliance with the relevant standard or furnish a test certificate to the relevant standard from an
independent testing authority.
Submit to the Superintendent for approval details of the proposed bending, splicing and the like.
Welding of reinforcement shall not be permitted. If required due to the nature of the works, obtain
permission from the Superintendent.
3.07.02 PROTECTIVE COATING
Unless otherwise shown on the drawings, if an element is specified to contain protective coated
reinforcement, provide the same coating type to all element reinforcement and embedded metal
items including tie wires, stirrups and the like.
3.07.03 FIXING REINFORCEMENT
Tolerance on position shall be to AS3600 Clause 19.5.3.
All reinforcement shall be placed in the positions as shown on the drawings. Secure the
reinforcement against displacement by tying at intersections. Bend the ends of wire ties away from
nearby faces of forms. The ends of the ties shall not project into the concrete cover.
The concrete cover as shown on the drawings shall always be maintained.
Stirrups and ligatures shall pass around the main bars and be securely wired.
3.07.04 REINFORCEMENT SUPPORTS
Use purpose-made concrete, metal or plastic supports. Provide a protective coating to ferrous metal
supports which extends to the surface of the concrete.
Provide maximum support spacing at 650 mm or as directed.
3.07.05 LAPPING OF REINFORCEMENT
Lapping of reinforcement or fabric shall be as required by standard AS3600.
In no case shall the lap length be less than 25 times the diameter of the reinforcement plus 150 mm.
3.07.06 CLEANING OF REINFORCEMENT
At the time concrete is placed, reinforcement shall be free from mud, oil, grease and other nonmetallic coatings and rust.
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Launceston City Council
General Specifications
Concrete
3.08 00 PLACING
3.08.01 PLACING AND COMPACTION
All concrete shall be placed in the dry conditions. No concrete shall be placed until the forms,
reinforcing and foundations as applicable have been inspected and approved.
Concrete shall be discharged by means of suitable clean chutes, troughs or pipes. Do not use water
to facilitate the movement of concrete.
In vertical pours, the free fall of concrete shall be limited to 1500 mm. As far as possible keep chutes
vertical and full of concrete during placement.
Place concrete in layers such that each succeeding layer is blended into the preceding one by the
compaction process. Concrete exposed to rain before it has set, shall be protected by suitable
covers.
Minimize shrinkage effect by pouring the sections of the work between approved construction joints in
a sequence such that there will be suitable time delays between adjacent pours.
Use immersion and screed vibrators accompanied by hand methods as appropriate to remove air
bubbles and compact the concrete. Use form vibrators where use of immersed vibrators are
impracticable.
Ensure concrete is fully compacted and entrapped air removed. Avoid over vibration that may cause
segregation.
Do not allow vibrators to come into contact with partially hardened concrete or reinforcement
embedded in it. Do not use vibrators to move concrete along the forms.
3.08.02 TEMPERATURE OF CONCRETE
The equilibrium0 temperature of all fresh concrete measured at the point of placement shall be not
greater than 32 C and not less than 10o C.
0
Whenever the temperature of the concrete is likely to rise above 32 C, the Contractor shall have the
means available for holding it below that level.
For failure to meet these provisions, the Superintendent may suspend concrete placing operations.
3.08.03 CURING AND PROTECTION
Commence curing immediately after finishing, and cure continuously for 7 days.
Curing may include any of the following methods:
•
•
•
•
•
Ponding or continuous sprinkling with water.
An impermeable membrane.
An absorptive cover kept continuously wet.
Steam curing.
An approved curing compound.
Contractor shall protect the newly placed concrete from damage due to load overstresses, heavy
shocks and vibrations. Do not place construction loads on self-supporting structures, which will
overstress them.
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Launceston City Council
General Specifications
Concrete
3.09.00 PRECAST UNITS
3.09.01 REQUIREMENTS
Standard to AS3600 including subsections. Precast concrete units shall be manufactured by an
approved subcontractor.
Identify each unit by marks which shall:
• remain legible until after the unit has been fixed in place
• show the date of casting
• show the correct orientation of the unit.
If requested by the Superintendent, submit shop drawings of precast units showing the proposed
details for their design, manufacture, assembly, transport and installation.
3.09.02 PRECAST DIMENSIONAL TOLERANCES
The finish precast concrete shall be within the tolerances as stated below:
Maximum misalignment across
from joint
=
2 mm
Deviation from correct position =
1 mm
3.09.03 HANDLING PRECAST UNITS
Do not lift or support units at other than specified points without prior approval.
The precast units shall be:
• protected against staining and discolouration
• transported, stored and erected in a manner which will not overstress, warp or damage them
• adequately braced and supported during handling and erection to ensure proper alignment and
safety.
3.10.00 JOINTS
3.10.01 CONSTRUCTION JOINTS
Make construction joints where shown on the drawings. Do not relocate or eliminate a construction
joint without the prior approval of the Superintendent.
Before fresh concrete is placed at a construction joint, roughen and clean the hardened concrete
surface of the joint. Dampen the hardened prepared concrete surface without leaving free water, just
prior to placement of fresh concrete.
Unless otherwise shown on the drawings or specified, the adjoining surfaces shall be butt jointed.
3.10.02 MOVEMENT JOINTS
Construct movement joints in the locations and to the details shown on the drawings.
Contraction joints shall be unreinforced joints with a bond-breaker coating separating the concrete
joint surfaces.
Expansion joints shall be unreinforced joints with the joint surfaces separated by a compressible filler.
Control joints shall be a weakened plane contraction joints created by forming a groove. Extend the
groove at least one quarter the depth of the section.
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Launceston City Council
General Specifications
Concrete
Joint dowels shall have reinforcing rod dowels in expansion or contraction joints as shown on the
drawings. Embed each dowel normal to the plane of the joint, so that half the dowel lies on each side
of the joint. Heavily grease or bitumen coat one half and fit an expansion cap to that end.
Joint filling material shall be of the approved type and shall be placed as recommended by the
manufacturer.
3.10.03 WATER STOPS
Install waterstops where shown on the drawings surrounded by fully compacted concrete.
Locate and secure waterstops so that:
• their correct positions in the finished work are ensured
• the proper placing and compaction of the concrete is not inhibited, and
• reinforcement is not displaced from its correct position
3.11.00 PAYMENT
3.11.01 PAYMENT
Payment shall be based on the Schedule of Rates as tendered for the contract. The following unit of
measurement may be used in the preparation of the Schedule of Rates if lump sum prices are not
required.
• Structural concrete is measured in cubic metres. This will include concrete, reinforcement,
formwork, joints, placing, compaction and the like necessary for placing concrete.
• Manholes, side entry pits and precast concrete are measured in numbers.
• Non-structural concrete such as Kerb and Channel is measured in linear metres.
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