PROPOSED 3-STOREY DATA CENTRE BUILDING DEVELOPMENT AT NONGSA –BATAM ISLAND,

INDONESIA

ARCHITECTURAL DIVISION A.4 - ARCHITECTURAL PRECAST CONCRETE

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4.0 ARCHITECTURAL PRECAST CONCRETE

4.1 Manufacturer’s Qualifications

The Contractor shall ensure that the manufacturer’s qualifications are as follows:-

Precast elements: Casting plant by manufacturer allocated for this job and facilities to produce
elements in sufficient volume to insure proper job progress. In addition, manufacturer must have
successfully completed five projects equal or greater in complexity and size than the Works. Plant
or plants used shall have been in operation no less than ten (10) years.

Naming of manufacturer shall not relieve manufacturer from responsibility of having to comply fully
with detailed and specific requirements outlined in these specifications, drawings, and as directed
by the Employer’s neither Representative; nor does naming of manufacturer relieve the Contractor
from his responsibilities, duties, and/or liabilities in relation to such subcontractor, supplier or
manufacturer.

Manufacturer shall maintain engineering organization or hire professional engineer who is (a)
familiar with precast concrete techniques as practiced in Singapore to an acceptable international
standard, (b) familiar with type of equipment, manner of production proposed.

Structural design of reinforcing, sizes, numbers, types, locations of cast-in items: shall be the
responsibility of the Contractor to coordinate with manufacturer. Requirements for concrete and
reinforcement are set out in structural specifications.

Manufacturer shall be certified by Singapore Green Building Council and attained the status of ISO
45000.Work specified herein: shall be furnished and erected by one manufacturer unless
otherwise approved by the Employer’s Representative or Project Consultant.

Recommended Manufacturer: Robin Village Development Pte Ltd or approved equivalent.

It should be noted that the Employer’s Representatives requires develop the color and the texture
further together with the manufacturer immediately after the award of the contract. As such, the
Contractor shall duly oblige to work with the Employer’s Representatives on this design refinement
process including the R&D of finishes on a without any time and cost implication basis.

4.2 Performance Requirements

The Contractor shall be responsible for the manufacturer’s engineering design of all architectural
precast concrete work, including connections, reinforcement and installation of the architectural
precast concrete units. The Contractor shall also be responsible for the locating and placing of all
items required for connections to all other work.

Units having any dimension smaller or greater than required, and outside the specified tolerance
limits, will be considered deficient and shall be rejected if the appearance or function of the unit is
adversely affected, or if the larger dimensions interfere with other construction. Repair or remove
and replace rejected units as required to meet the construction conditions.

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Engineering design of the architectural precast concrete – refer to Civil &Structural Engineering
Specifications. Engage a PE (Structural) to carry out the design of the structural supports for the
precast system and submit for BCA approval as a QP for this design.

Unless otherwise agreed by the Employer’s Representative, ensure all of the Works comply with
the relevant requirements of the Standards and Codes listed below or referenced in the body of
the Specification. Alternative Standards and Codes may be proposed for approval by the
Employer’s Representative, provided it can be demonstrated that the alternative Standards and
Codes comply with the requirements of the standards specified. All Standards and Codes quoted
are the current version, unless specific year references are noted.

Singapore standards

SS 555 Code of Practice for Protection against Lightning protection

SS CP81 Precast concrete slab and wall panels
SS EN 1992 Structural use of concrete
SS CP65 Structural use of concrete
SS 26 Ordinary Portland cement
SS 31 Aggregates
SS 32 Steel fabric for reinforcement of concrete
SS 289 Specification for Concrete
SS 320 Admixtures
SS 18 Cold reduced steel wire for reinforcement of concrete
BS 1014 Pigments for Portland cement
BS 4255 Specification for non-cellular gaskets
BS 5080 parts 1&2 Structural fixings in concrete
BS 5250 & CIBSE handbook Code of practice for control of condensation in buildings
BS 5889 Silicone sealants
BS 5950 Structural use of steel
BS 6213 Selection of Construction Sealants
BS 6213 Loading of buildings
BS 6744 Stainless steel bars for concrete reinforcement
BS7079 Steel preparation
BS EN 24032, 24033 Carbon steel bolts and nuts
BS EN 10056 – 1&2 Carbon steel angles
BS EN ISO 11600 Building construction. Jointing products. Classification
and requirements for sealants.
BS EN 100025 Hot rolled steel
BS EN 10029 Stainless steel
BS EN 10048 Stainless steel
BS EN 10088 Stainless steel
BS EN 10258 Cold-rolled stainless steel and narrow strip and cut
lengths – tolerances on dimensions and shape
BS EN 10259 Cold-rolled stainless steel wide strip and plate/steel –
tolerances on dimensions and shape
BS EN 10021, General technical delivery requirements for steel and
iron products
BS EN ISO 3506 parts 1&2 Stainless steel fasteners
BS EN 1461 Galvanising
PD 6484 Bimetallic corrosion
CIBSE handbook Thermal performance

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General
Precast concrete shall (be / have):-
 Concrete cover to all reinforcement shall comply with latest code; subject to a minimum
reinforcement cover 30mm unless otherwise agreed.
 No spacers visible or less than 10mm sub-surface in the finished panel.
 No voids or honeycombing
 Internal air seal and vapor barrier continuous past slab edge
 No standing water
 Joints, connection, sealants shall be designed for protection against water, weather,
corrosion and fire so as to provide continued water and weather tightness and structural
integrity of the buildings.

Resistance to Climatic and Environmental Conditions

Weather resistance
Limit airflow through the precast concrete, from the exterior surface to the interior surface through all
joints, to the specified air leakage rates quoted below when subjected to wind induced pressures or
suctions across the wall. There shall be no region of concentrated airflow through the precast
concrete joints or at any interfaces.

Prevent leakage of water into the interior of the building from the outer face of the assembly, resulting
from wind pressure kinetic energy, gravity, surface tension, or capillary action with any combination of
wind and precipitation likely to be experienced.

Ventilate cavities to be compartmentalized by the use of flashings and baffles. No cavity shall be
more than 12m high and 50m long. Vertical flashings or baffles to be added at corners.

Prevent water entering into those parts of the precast concrete that would be adversely affected by
the presence of water. Maintain weather tightness under reasonably anticipated imposed loads and
thermal, structural or other movements. No seepage to occur through the concrete.

All Precast Concrete Claddings shall be treated with a hydro-phobic substance /Water repelling
agent Wacker Silres BS38 or approved equivalent either in the factory or on-site. The type of hydro-
photic treatment shall be submitted for approval by Employer’s Representative prior to application.

Avoidance of algae growth

Where applicable, agree suitable measures with the Employer’s Representative for protecting
against algae growth on the surface of the concrete. Sealants must be tested on sample panels and
approved by the Employer’s Representative.

Thermal Stress
Resist cracking to precast concrete caused by thermal stress.

Condensation performance
Resist the formation of condensation on visible surfaces, interstices or locations where it is unable to
drain.

Resistance to acid rain

Obtain local pollution data and rainfall data. Design the precast concrete to maintain integrity and
appearance for the design life of the building. Advise any coatings, maintenance and cleaning
treatments necessary.

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Design for thermal and condensation performance

Use insulation of appropriate performance to provide adequate level of performance without localized
cold bridging where insulation must be locally reduced in thickness such as anchor positions. Use
vapour barriers as necessary to eliminate condensation around the precast concrete.

Climatic Data

Assume:-
Ambient temperature range 16°C to 40°C
Radiant temperature range 16°C to 80°C
Relative humidity range 90%±10%
Environment Coastal

Gather any additional climatic data required from the Singapore Meteorological Observatory.
Submit for review to the Employer’s Representative any additional assumptions concerning
temperatures, humidity levels, etc.

Structural Design and Loadings

General
Refer to structural specifications on precast concrete works.

Vibration and repetitive loading

Resist working loose of anchors and other components due to the effects of vibrations, or cyclic
effects of load, deflections and thermal expansion.

Locked in stresses
Avoid the introduction of locked-in stresses that may be detrimental to the performance of the
precast wall.

Building Movements and Structural Tolerance

Structural Movement and Movement between Works by Others

Accommodate the following movements in combination; without any reduction in the specified
performance, refer to the Employer’s Representative for further guidance and data for calculation
input:
 Deflections and movements of the structure and building wall under design loads.
 Changes in dimension and shape of building elements arising from building movements,
including settlement, shrinkage, elastic shortening, floor beam deflections, creep, wind sway,
twisting and racking and thermal and moisture movement.
 Changes due to movement of any joint in the supporting structure or building frame.
 Deflection of framing members under design dead loads and live loads. Incorporate these
calculations in the design.
 Thermal and moisture induced movements of the precast cladding. Incorporate these in the
design based on maximum range of temperature and humidity.
 Propose nominal, minimum and maximum joint widths accounting for tolerances and
movements for the Employer’s Representative’s acceptance.

Structural Tolerances
Refer to structural specifications on precast concrete works.

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Accommodate tolerances on structure and window openings as indicated below to the respective
works:-

Works Tolerance
Floor levels (floor to floor) ± 20mm
Slab edge plan dimensions ± 30mm
Columns and wall location on plan in all directions ± 20mm
Verticality H/500
Inserts (line and level) ± 10mm
Masonry set-out ± 15mm
Floor and ceiling finish level ± 5mm
Floor and ceiling position from grid ± 5mm
Wall finishes position from grid ± 5mm
External finishes level ± 20mm

Fire and smoke performance

Install fire and smoke stopping at all voids and penetrations between compartments at designated
locations to achieve the specified fire and smoke stopping performance.

The overall wall construction, including any upper lining wall must meet the following criteria:-
 2 hours fire rated with relevant certificates.
 Non-combustible materials. Do not include materials that readily support combustion or add
significantly to the fire load or give off toxic fumes.
 Fire and smoke stopping- Prevent the passage of smoke from floor to floor in accordance
with the requirements of B(C)R and BS 476: Parts 20-24.

Thermal performance
Achieve a thermal resistance as specific to comply with Green Mark requirements.

Acoustic performance
The total wall construction shall achieve the following STL values against noise break-in at all joints
and interfaces:-

Frequency(Hz) 125 250 500 1000 2000 4000

STL (dB) 25 27 32 33 30 26

Achieve resistance to flanking and floor to floor sound transmission of STC46 unless indicated
otherwise.

Functionality

Appearance
Type : Free of pinholes and off form with thickness of 200mm.
Achieve the mandatory geometry and presented on the architectural drawings. Not panel shall be
less than the intended full height as stated in the drawing. There shall be no horizontal joint for each
panel to the entire height.

Achieve colors and appearances presented on the architectural drawings. Submit sample panels to
illustrate the proposed surface color, texture and variability.

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Drainage
Design and install so that drainage of rainwater is predominantly at the outer face. The contractor to
ensure that drainage provision does not permit insect entry into drainage routes and ensure
continuity of weather tightness to adjacent roof waterproofing finishes and upstands.

Infestation
Resist attack or infestation by micro-organisms, fungi, insects, reptiles, birds or bats and rodents.
Have no openings in or around the precast concrete c that permit entry of insects, reptiles, birds or
bats and rodents.

Lightning protection
Meet or exceed the requirements of latest prevailing SS 555. The Contractor shall coordinate as
necessary between the precast concrete cladding and the main lightning protection systems for the
building and shall propose appropriate connection points. No external tapes will be accepted.

Durability and Maintenance

Facing mixes may be used provided they are integral to the panel and do not increase the water
absorption or carbonation resistance.
Do not use carbon steel in locations subject to wetting or condensation or where this will result in
corrosion; shortening their design life or compromising safety, however long-term; or, causing rust,
staining; or, establishing a bimetallic cell with other metals or carbon.
Identify materials and components which under normal service conditions cannot meet the specified
design life and design to allow their monitoring and replacement. Gaskets seals and baffles are to be
accessible for replacement.

Stain Resistant Test

Tested to latest prevailing SS 483: 2000(Annex G)/ ISO 13006 with staining agent including but not
limited to coke, vinegar, coffee, olive oil, soya sauce, tomato sauce and chili sauce etc..
Method of Testing according to latest prevailing ISO 10545-1 with Sealer Laticrete Guard sealer or
approved equivalent

4.3 Submittals & Proposal

The design intent including type and locations of the precast concrete are indicated in the
drawings and schedules. Base on the information supplied, engage qualified and experienced
personnel to carry out and submit the following items for the Employer’s Representative ’s
acceptance:-
Design Development
Develop all necessary details for the fabrication and installation of the precast system, and to meet
with the performance requirements as set out in Division 4.2 above. Details to develop may
include shape and sizing of components, structural support, accessories, joints, waterproofing and
connections to the building etc. The contractor shall ensure the adequacy and suitability of the
size, position and details of lifting and erection inserts and any additional reinforcement bars
required for handling and erection purposes shall be submitted to the Employer’s Representative
for approval prior to commencement of works.

Mould and formwork

Design all mould and formwork for the fabrication of the precast elements including all
accessories for the lifting, handling and storage of the elements.

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Temporary supports
Design to provide all necessary temporary supports and ensure that the precast elements are
stable after erection but before the building structure are completed. Provide all necessary
precautionary measures to ensure that the structure is not subjected to loads that will cause short
or long-term distress to any part of the concrete structures.

Samples/Mock Up
Prior to production fabrication of precast concrete units, the Contractor shall submit samples,
prototypes and demonstrations of fabrication and installation as required by Employer’s
Representative. A min 3 samples of 1.2m X 1.2m size sample of each shape and type of the
required precast concrete units at manufacturer’s plant for Employer’s Representative’s approval
to agree on the extent color and texture of the off form surface.

The Contractor shall sample panels to illustrate the major junctions of principle components. Do
not start mass-fabrication of precast concrete units until the full-size sample has received the
Employer’s Representative’s approval.

Form materials are subject to rejection if forms used do not provide the finish specified. Accepted
full-size sample shall be delivered and set up for display at the job site, be adequately protected
from damage, and shall serve as the standard of acceptance for similar precast concrete units
installed in the work, which shall be equal to and correspond in all respects to the approved full-
size sample.

Shop Drawings
The shop drawings shall include plans, elevations, sections and details noting dimensions,
profiles, materials, finishes, anchoring methods, connections, joints and the treatments and large
scale details of interfacing with other materials and provisions to accommodate the work of other
trades. The contractor shall require
checking and/or ensuring the details for such precast concrete components are adequate and
suitable for the Works and there are no discrepancies. The contractor shall bear the responsibility
and bear all the costs and expense for all rejections, reinstatements and reproductions of such
precast concrete components directly and/or indirectly resulting from and /or out of any
discrepancy, unsuitability and discrepancy in the Drawings.

The mould drawings shall include:-

 Surface treatment of mould for casting and lifting operations.
 Method of concrete consolidation and compaction such as external vibration, internal
vibration, table vibration, adjusted slump and mix method.
 Method of curing, demoulding and storage of precast components
 .
The erection drawings shall include:-
 Erection sequences and handling requirements.
 Calculation and positon of sizes of backers/shims, temporary props, bracings and their
installation method clearly shown
 Calculation and details of method of positioning and supporting unconnected precast
concrete components including temporary bracings, struts and props.

The waterproofing joint drawings shall include:-

 Procedure and sequence of installation of sealants on Site in their relation to erection
sequence and handling requirements.

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Product Literature
Submit manufacturer’s product data, catalogs, test data, color charts and other information as
directed by the Employer’s Representative. The Contractor shall provide certification from sealant
manufacturer that the sealant manufacturer has reviewed all sealant details and finds same
suitable for the purpose intended, compatible with and will not stain the surfaces with which they
are in contact.

Statement as to compatibility, adhesion sufficiency and non-staining shall be accompanied by

actual test results on production substrates performed in accord with applicable ASTM
procedures.

In the event of a potential stain problem the Contractor shall modify design to accommodate
characteristic of a sealant which does not have potential staining characteristics at no additional
cost to the Owner.

Methods
Propose method of fabrication, erection/installation.

Weather/waterproofing
Propose details of weather/waterproofing including interfaces to windows and adjacent claddings.

Quality Control Plan

Propose quality control plan recommended by the manufacturer.

Maintenance Manual
Propose maintenance manual recommended by the manufacturer eg cleaning method for surfaces.

Co-ordination with other Works

Co-ordinate the precast concrete cladding works particularly the interfacing with the following trades:
 External and internal masonry
 Structural frame
 Windows and doors (factory fitted or site installed into openings)
 Lightning protection systems
 External finishes
 Mechanical and electrical services

Factory Procedures
Submit proposals for materials delivery, storage and batching. Identify every panel uniquely so that it
is traceable through materials used, cube results, stage inspection records.

4.4 Delivery, Handling &Storage

The Contractor shall deliver precast elements to the site in whole undamaged units, in
conformance with the reviewed samples. Precast elements should be loaded and delivered with
proper supports, frames, cushioning and tie-downs to prevent in-transit damage. Adequate
packing and protection to the edges of precast elements should also be provided. Identify every
panel uniquely so that it is traceable through materials used, cube results and stage inspection
records.

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The handling process mainly involves the removal of the precast elements from the mould,
transportation to the storage yard, loading and unloading operation and erection of these elements
at the job site. Different sets of lifting points and cast-in devices are to be used for the various
handling stages; the elements are to be handled in a way that is consistent with their shapes and
sizes, to avoid excessive stresses or damages.

At all times protect lifting hooks and devices from rusting with liquid galvanizing. Recess lifting
hooks and after removal paint the cut ends with liquid galvanizing and fill the recess with grout.
Protect against water particularly holes, reglets, false joints and other recesses

The Contractor shall state handling and lifting procedures proposed for use by the Contractor. The
handling techniques for precasting, demoulding, storage and transportation adopted shall not
overstress such pre-cast components. It is the responsibility of the contractor to provide at his own
cost and expense, any additional steel reinforcement bars required for his handling techniques to
ensure that such precast concrete. Check and allow for:-
 Adequacy of design reinforcement to resists handling stress
 Provision of additional reinforcement if required
 Exact number, size and location of lifting inserts and other devices: and
 Proper struts and support locations for storage and transportation.

Store materials under cover in a dry and clean location, off the ground and remove materials
which are damaged or otherwise not suitable for installation from the job site and replace with
acceptable materials. Appropriate stacking method should be adopted to store the precast
concrete elements to prevent cracking, distortion, staining or other physical damage, and so that
markings are visible. The contractor shall ensure that storage of precast components on Site shall
not cause any damage to the contracture works. Any rectification work shall be done to
satisfaction of the Employer’s Representative at the contractors’ cost and expense.

4.5 Fabrication

Requirements and Standards

The minimum concrete strength of precast components required for handling, demoulding,
storage, transportation and erection are checked and submitted to the Employer’s Representative
for approval prior to commencement of the fabrication work.

Factory cast concrete elements indoors with maximum quality control. Job site or yard casting is
subject to Employer’s Representative’s approval.

Provide elements with same degree of uniformity, color, texture and free of rust spots or other
stains to match reviewed submittals.

Forms shall be accurately constructed to produce members to dimension, shape, configuration,

and profile indicated. When not otherwise indicated, construct forms to produce smooth concrete.

Concrete reinforcements, lifting reinforcements and concrete inserts and anchorage devices shall
be placed and secured against movement as required.
Provide permanent markings in precast units to identify pick-up points and orientation in the
structure, complying with the markings indicated on the final shop drawings. Imprint the date of
casting on each precast unit where it will not show in the finished structure.

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Reference Standards: Fabricate precast concrete units so as to comply with the manufacturing and
testing procedures and quality control recommendations of Precast Concrete Institute’s MNL-116
and MNL-117 “Manuals for Quality Control” for Production of Precast Prestressed Concrete Products
and of Architectural Precast Products, except as modified herein.

The Employer’s Representative shall have the discretion to inspect the manufacturing plant and the
precast concrete components at all times. If the inspection is not conducted at the plant, this shall
not relieve the contractor form his responsibility in manufacturing an acceptable product, and the
Employer’s Representative shall at his liberty reject any precast concrete components on the Site
not complying with the performance requirements even though no pant inspection has been
conducted.

4.6 Finishes

Provide consistent finishes for exposed concrete matching to approved samples and mock-ups
and the approved control samples.

For those items not exposed to public view, provide smooth form finish’ or as specified in
drawings. Remove spacers and surface contaminants / debris trapped in face. Apply any post
applied surface treatments required to achieve the architectural quality finish as specified.

Precast Concrete Claddings - Off Form Exposed Surfaces.

Application: EW106 at Block 1

Finish: Off Formed Surfaces with free of pinholes free of honeycombs, form marks, concrete
droppings or other blemishes that would telegraph through the panel. Provide a finish surface free
of laitance, grease, form release treatments, efflorescence, curing compounds or other foreign
material that would adversely affect bonding of any subsequent coating.

Colour: The color scheme shall match the Employer’s Representative’s design reference panel
for both the Precast Concrete Claddings. The exact color shall be finalized prior to the
commencement of full scale production. The color shall be integral with the panel, not painted.

Textures: The textures shall be integral with the Precast Concrete Claddings. It is determined that
there shall be at least three different textures to be used in this project, similar to the “honed
finish”, ‘flamed finish” and “polished finish”. It should be highlighted that a combination of the at
least 2 to 3 different textures shall be used together on the same panel rather than on a ‘one-
texture on one- panel’ basis. The exact final textures and the combination of the textures shall be
subject to the approval of the Employer’s Representative.

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Acceptability of Appearance -Tonality must be consistent. Finished construction in place

shall present a uniform, pleasing appearance when viewed in good typical lighting with the
naked eye at a distance of 3m and shall show no imperfections at a distance of 6m.

The range of total acceptable color (lightness, color saturation and hue) variation shall not
exceed CIELAB 3.0 provide that the difference in hue alone does not exceed CIELAB 1.0 as
defined by the International Commission of Illumination, 1976 Standards.

Finish of Formed Surfaces

All exposed formed surfaces and exposed troweled surfaces of Architectural precast concrete
units shall have smooth “as-cast” finish, including:
 Typically, acid etch all exposed elements to achieve uniform color and texture.
 It is the intent of these specifications that no patching of Architectural precast concrete will
be required. In the event remedial action is required, it shall consist of patching with
acceptable epoxy mortar. Only areas directed by the Employer’s Representative shall be
patched. No patching shall be done without the Employer’s Representative’s approval.

Finish of Unformed Unexposed Surfaces.

All unformed surfaces of precast concrete shall be solidated, brought to a proper level with a
straight edge, floated and then given the following finish:
 Uniform Troweled Finish: Typically for all surfaces not exposed to view.
 Exposed Unformed Surfaces: All panels exposed on 2 sides shall be floated and/or
troweled on the unformed surface in a manner which will enable finishing to match the
formed surface. Floating and/or troweling shall be consistently performed on all unformed
surfaces. All unformed surfaces shall be oriented as indicated on the drawings.
Unless otherwise stated, all unformed surfaces (face up casting) to be steel troweled finish.

Design and Selection of Architectural Quality of Finish

Provide samples for Employer’s Representative for review and selection of finish. When finish is
selected produce 1m² finish range samples for review by Employer’s Representative. Agree 5
accepted 1m² finish range samples with Employer’s Representative. Saw these into three equal
pieces retain one set at the factory, one at site and one with the Employer’s Representative.
Identify concrete mix and sources, mould properties casting and curing, post casting treatments
and other details to allow consistent panels to be produced. Facing mixes may be used provided
they are integral to the panel and do not increase the water absorption or carbonation resistance.

4.7 Installation

All precast concrete components shall be inspected and approved by the Employer’s
Representative before the erection and after installation. Any unauthorized erection and
installation works may be rejected and necessary actions taken against the contractor.

Prepare, install and check that the precast components are within the specified erection
tolerances prior to calling for inspection and approval by the Employer’s Representative. Erect
precast concrete units and accurately install in place with mechanical hoisting equipment more
than adequate for the loads. Do not install precast units until concrete has attained its design
strength. Maintain precast concrete unit in upright position at all times. Handle units only by
indicated lifting devices or cushioned pads, and in a manner that will not overstress or damage the
unit.

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For correct performance and appearance of the structures, check and ensure that the precast
components are located at the center of their theoretical location on the building and adjusted to
accommodate adjacent components, proper joint width, and alignment with adjacent precast or in-
situ members. Unless otherwise instructed by the Employer’s Representative, the permissible
erection tolerances shall be as follows:-

Works Tolerance

Distance between Edge of Panels at Joint

a) For panels with dimension up to 6m ± 5mm
b) For each 3m increment in excess of 6m ± 2mm

Joint Tapers ( Panel Edges not parallel)

½mm
a) Per linear 300mm of joint
2mm
b) Minimum allowable
9mm
c) Maximum for entire length

Panel alignment
3mm
a) Alignment to horizontal and vertical joints
3mm
b) Jog in alignment of matching edges
± 6mm
Location of openings in precast concrete components

Vertically of the walls

± 35mm
a) Entire height of building
st th ± 25mm
b) 1 to 4 floor
± 10mm
c) Each storey height
Parapet alignment at access balcony.
Deviation in plan from straight line parallel to specified linear building
line:- ± 1mm per metre
a) Any interval less than 6m ± 25mm
b) Any 50m length
Coping level ± 5mm
a) Any interval less than 6m ± 25mm
b) Any 50m length
Vertically of column Same as wall
st
Column alignment at 1 storey
± 12mm
a) In between columns up to 6m apart
± 30mm
b) Entire length of building

Precast concrete units shall be installed in accordance with applicable industry standards. Upon
request, the precast concrete producer shall provide installation instructions.

Necessary precautions shall be taken to protect precast units from damage after they have been
installed. Wedges, spacers, or other setting appliances which are likely to cause staining removed
from joints as soon as practicable.

The Contractor shall co-ordinate work of other trades whose work must be performed, before
erection of precast elements.

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Welding: Perform all welding in compliance with AWS D1.0 and D12.1, including qualifications of
welders.

Protect units from damage by field welding or cutting operations and provide non-combustible
shields as required.

The Contractor shall install approved sealants between all precast-to-precast joints with
appropriate backer rods to control depth. Install by gun as per the sealant manufacturer’s
recommendations. Tool to proper profiles to assure adhesion to sides of joint.

Install sealants and backer rods into the false joints and duplicate the appearance of the regular
true joints. Apply and cure sealants in accordance with their manufacturer’s directions on minimum
and maximum temperature and RH conditions and achieve the depth to width geometry.

Work to prevent three-sided adhesion, use appropriate backer rods, tapes, surface preparation and
primers as manufacturer’s directions and, tool off sealants neatly
Where water tightness is a necessary performance characteristic of the precast concrete unit’s end
use, watertight joints, pipe-entry connectors and inserts should be used to ensure the integrity of the
entire system.

After inspection of the erected precast components, the Employer’s Representative shall at liberty to
reject any precast components on Site not complying with the design or specification requirements.

4.8 Materials

Flashing
Acceptable materials are 300 series stainless and either anodized or painted aluminum
sheet, depending upon location and application or use. Minimum thickness is 1mm for
aluminum or stainless steel. Aluminum sheets shall have bituminous coating to protect
against dissimilar materials.

All joints to be lapped and sealed to a minimum of 150mm. Provide sealed lap joints, end
dams and transitions to gutters.

Neoprene sheet is not acceptable for primary gutters which shall be metal with suitable
corrosion protection.

Fasteners
Fastener requirements listed herein are applicable to screws, bolts, nuts, washers, rivets and
pins. All fasteners unless specified otherwise shall be 316 stainless steel, nonmagnetic.
Finish exposed fasteners may only be used if approved by the Employer’s Representative.
The work shall be designed to conceal all fasteners.

Unexposed fasteners located inside of the vapor retarder may be steel with cadmium and
colored chromate plated, meeting ASTM B 696, Class #5, Type II finish 5 um thick 0.0005).

All non-stainless fasteners being used in a structural application must meet the minimum
requirements of SAE J429 Grade 5. Grade 8.2 fasteners, high strength bolts of non US
origin, or high strength bolts that are zinc plated shall not be used.

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Mill test reports for all structural grade bolts shall be submitted to the Employer’s
Representative for his approval prior to installation of those bolts on the job.

Powder actuated fasteners are not acceptable.

All bolted connection shall use matched material and grade nuts, bolts and washers.

Gaskets and Baffles

All gaskets/baffles shall be silicone, Neoprene or SCR (Silicone Compatible Rubber). All
gaskets, baffles, weather stripping and spacers shall have a continuous mechanical
engagement to framing members. Non-staining type shall be used.

4.9 Workmanship

Only competent workers who are properly trained to handle and erect precast components should
be employed. Only qualified welders shall be employed for welded connections.

Highest standards of profile, aggregate appearance will be insisted upon by Employer’s

Representative for his approval. No regrouping or patching will be permitted for production faults
or for handling injury at plant, with exception of very minor repairs which will be inconspicuous, and
referred to the Employer’s Representative both for approval to repair and then approval with
guarantee for patching at site, as specified herein.

Areas approved for patching shall be kept moist for 24 hours before patching. Curing of patches:
as directed, with epoxy bonding agent.

Elements which are defective or damaged in any way or warped to any extent beyond allowable
tolerances specified herein: rejected, immediately removed from the site, replaced accordingly, at
no additional cost to Employer.

Especially note that edges, profiles, corners, arises, returns shall be sharp, with aggregate
distribution even, not noticeably varying from flat areas of elements.

Precast elements shall have true surfaces. No broken or warped units shall be installed on structure.
Honeycombs or other defects shall be cause for rejection.

Field conditions shall be determined by actual measurement so that precast concrete components
and joint sealant installed satisfy design or specifications and are within the specified erection
tolerances.

Ensure good construction practice is adhered to while the precast concrete component are on the
site and bracing or props shall be provided to maintain the required positon, stability and alignment of
each precast concrete components prior to permanent joining or connection.

Each precast concrete components shall be individually adjusted and accurately positioned within the
erection tolerances. Horizontal and vertical joint shall be kept correctly aligned and positioned, and
uniform joint width shall be maintained as erection progresses. Adjustment or changes in
connections, which could induced additional stresses shall be reviewed and approved by the
Employer’s Representative.

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Site Repairs - Inspect immediately after at installation for damage and repair cosmetic damage and
subject to review by Employer’s Representative. Repair impact damage and subject to review by
Employer’s Representative. Remove any cracked or structurally damaged panels and replace with
new panels whilst panel can still be removed. In the event of damage at a later stage when a panel
cannot be taken out, submit proposals to the Employer’s Representative for review.

All damaged/defective panels will be rejected unless remedial measures were accepted and
carried out to Employer’s Representative’s satisfaction.
For defective/damaged works which need to be replaced, concession to this requirement will only
be given if the proposed repair procedure is authorized by the Employer’s Representative and
complete and warranted repair of the damage is achieved. Do not give a replacement unit the
same reference as the rejected unit it replaces. All repaired precast components shall be
architecturally and structurally acceptable to the satisfaction of the Employer’s Representative.

4.10 Test

Water Tightness Test to External Full Height Precast Walls

General
Carry out tests on the external walls directly facing the exterior. Excluding access balcony walls,
parapet walls or determined by the Employer’s Representative to be excluded.

All external walls are to be subjected to a water penetration test in two parts:-
 The first test shall be conducted on completion of the external walls but before the
commencement of any finishing works on these walls.
 The second test shall be conducted on completion of plastering work internally.

Parameter
Water Intensity : 300mm/hr
: 1 liter/min/m of joint
Wind Pressure : 240Pa
Nozzle Inclination : 90 º to wall/window
Spray Duration : 10 minutes

Source of water
Water used to test the water tank prior to its sterilization. Sterilize the tank after completion of the
water test. Use PUB potable water only for re-test. Water Intensity: 300mm/hr and 1 liter/min/m of
joint.

Method of testing
Provide the following information to the Employer’s Representative for approval eight weeks
before carrying out the test:
 The equipment set up to conduct the test
 Procedure of the water test
 Pump capacity to deliver the required flow rate
 Method to suspend the nozzle

Place the nozzle so that it covers the whole wall panel.The panel will be considered to have
passed the test if no dampness or seepage appears on the internal surface of the wall panel or
adjacent areas during the spraying and within half an hour of completion of the spraying.

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Before carrying out the tests, the Contractor shall ensure that all mortar joints within the walls and
the joints between the concrete frame and brickwork are properly filled and do not permit the
passage of light. Joints allowing the passage of light shall be grouted with cement mortar (1:3).

External walls shall be tested in both cases from outside by direct hosing of the walls for a duration
of minimum 2 hours with a continuous jet of water from a water hose reel having a 4.5mm nozzle,
and a minimum running pressure of 4 bar held at a min 1800-2000mm away from the surface
under test to be further confirmed by the Employer’s Representative to check for weak areas.
The capacity of the water shall be 300 liters.

Water penetration for the second test shall be measured by means of a protimeter instrument
which is calibrated with color coding for reading of moisture content. The test is considered
satisfactory if the reading is in the green zone which indicates 17% water content. Any reading
beyond this point would indicate that the moisture content is too high and not acceptable.

In the event of failure of the test, the Contractor shall rectify the defective portions or reconstruct
any rejected wall and repeat the test. The cost of the tests including the supply and disposal of
water and all rectification works shall be borne by the Contractor.

4.11 Cleaning and Protection

After erection has been completed, approved by Employer’s Representative, protection, cleaning
and patching shall be the sole responsibility of Contractor.

Repair or replace any unit at manufacturer’s expense which does not comply with specifications,
approved shop drawings or approved sample

Protect precast concrete elements from time of manufacture until completion of erection of
adjoining work. Unless agreed otherwise by the Employer’s Representative, protection should
remain in place until all work potentially damaging to the components or their finish has been
undertaken.

Materials used for temporary protection shall be compatible with and subsequently removed from
the surface and finishes without detriment to the finish. The component suppliers and finishers
shall approve methods for removal.

Leave precast elements, premises clean; remove debris and other materials from job site. Clean
precast with steam or other acceptable method before final inspection.

Provide and maintain, until directed to remove; temporary protection for erected precast concrete
elements specified herein by using acceptable type of protection to prevent damage to installed
work.

END OF SECTION

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