Contract No. CV/2020/09
Particular Specification
Construction of Lei Yue Mun Public Landing Facility
SECTION 29 - PROTECTIVE COATING WORKS
GENERAL
Scope
29.01
(1)
This section covers the requirements on the use of coating
materials for the protection of the concrete structures, the
performance criteria and necessary tests that define
acceptance of the coatings.
(2)
Unless otherwise approved by the Supervisor, the coating
materials and workmanship shall comply with the
requirements of the Model Specification for Protective
Coatings for Concrete, July 1994 and its subsequent updates
published by Civil Engineering Department, Hong Kong
Government (herein referred to as ‘The Model
Specification’). In particular, the following clauses shall
be complied with:
(a)
Specific Requirements for Carbonation Resistance
(i)
Clause 19 “New
Construction”
-
(ii)
Construction
and
Older
Clause 19(2) with the minimum R-value for
the paint system shall be 150m; and
Clause 20 “Back Pressure Acting on Coatings”.
(b) Specific Requirements for Chloride Resistance
(i)
(ii)
Clause 22 “Concrete Subject to Chloride Spray
and Carbonation”
-
Clause 22(2); and
-
Clause 22(3) with the amendment that the
paint system shall be tested after 1000 hours
artificial weathering to Appendix 3 of the
Model Specification.
Clause 23 “Concrete Subject to Cyclic Immersion
in Seawater”.
(c) Specific Requirements for Tidal Works
(i)
Clause 29 “Concrete Subject to Cyclic Immersion
in Seawater; and
(ii)
Clause 30 “Wet Concrete Surfaces”.
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Contract No. CV/2020/09
Particular Specification
Extent of Coating
Submissions
Construction of Lei Yue Mun Public Landing Facility
29.02
29.03
Protective coating works are specified to retard ingress of
chloride in marine environment and/or carbon dioxide for marine
structures, thus preserving the integrity of the concrete structures.
The extent to be coated include:
(1)
A coating system shall be applied to the reinforced concrete
surfaces of the new structures. All reinforced concrete
surfaces above +1.35mPD except the deck surface shall be
coated with protective coating unless otherwise agreed by
the Project Manager.
(2)
For precast reinforced concrete units, all surfaces except the
deck surface shall be coated unless otherwise agreed by the
Project Manager.
(1)
One month prior to the commencement of the coating
application and before any subsequent change in coating
materials, the Contractor shall submit to the Supervisor
technical data sheets and test certificates regarding the
quality of materials and performance of products providing
the following information required in the Model
Specification, including but not limited to the following
information as appropriate unless agreed by the Supervisor
otherwise:
(a)
Salt spray resistance;
(b)
Salt water immersion;
(c)
Carbonation resistance
(d)
Water permeability resistance;
(e)
Weathering resistance;
(f)
Impact resistance;
(g)
Bond strength; and
(h)
Current test certificates supplied
manufacturer(s) or suppliers.
by
the
(2)
Supplied test certificates shall be current and issued within
5 years from the commencement date of the Contract.
(3)
The Contractor shall also submit to the Supervisor detailed
proposal for concrete surface preparation, materials for
making good surface defects and coating application
method (inclusive of staging of works).
(4)
No claim shall be approved for disapproval or amendments
to the above submissions required by the Supervisor. The
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Contract No. CV/2020/09
Particular Specification
Construction of Lei Yue Mun Public Landing Facility
approval by the Supervisor shall not relieve the Contractor
of his duties and responsibilities under the Contract.
Storage of
Materials on Site
29.04
(5)
No coating application works shall be carried out unless the
Supervisor has approved either fully or conditionally the
above submissions.
In the latter case, reasonable
conditions of the Supervisor’s approval shall be complied
with.
(1)
Materials shall be stored under cover, shaded from direct
sunlight, not in contact with a damp floor or ground, kept in
a controlled environment (where necessary) and shall be
used in the order of delivery. Materials that have in any
way deteriorated or stored beyond the manufacturer’s
recommended shelf life shall not be used. Proprietary
materials shall be stored strictly in accordance with the
instructions and recommendations of the manufacturers.
(2)
The material shall remain in its original sealed and properly
marked containers until use. Safety labels shall be
displayed in accordance with the statutory safety
requirements.
Service Condition
29.05
The selected materials shall produce durable protective barriers
of consistently high quality and to the specified requirements
taking into account the local climatic conditions and the
aggressive agents such as water borne chlorides, sulphates,
flotsam and other deleterious matters which may exist at the Site.
Samples
29.06
(1)
The materials and articles supplied for any purpose are to be
agreed by the Supervisor prior to their use in the works.
Within 2 weeks after the commencement of the Works, the
Contractor shall submit samples for the Supervisor’s
consideration and approval if appropriate before bulk
supplies are delivered to the Site.
(2)
Should any samples be rejected it shall be removed from the
Site immediately. In the event of rejection, alternative
specimens shall be submitted by the Contractor for the
Supervisor’s approval.
(3)
Accepted samples shall be kept on the Site to serve as a
standard for all subsequent material. If instructed by the
Supervisor, the Contractor shall carry out tests and provide
results to confirm the chemical content of the active
ingredients of the sample material and the material used in
the works at his own cost.
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Contract No. CV/2020/09
Particular Specification
Construction of Lei Yue Mun Public Landing Facility
MATERIALS AND WORKMANSHIP
Protective Coating
Systems
29.07
(1)
The protective coating system shall be epoxy generic type.
(2)
The protective coating system shall be proven and suitable
for application on damp and saturated existing and repaired
concrete surfaces.
(3)
The coating system shall consist of component applications
supplied by the same manufacturer.
(4)
Each consignment of materials shall be accompanied by a
manufacturer’s certificate indicating the date and location
of manufacture.
(5)
The colour of finished surface of the coating system shall be
approved by the Supervisor.
Water
29.08
All water used for any purpose in connection with the works
under this specification shall be clean fresh water taken from the
public supply.
Workmanship
29.09
(1)
The Contractor shall select methods to produce a durable
protective coating system to designated surfaces. The
works shall be of consistently high quality and to the
specified requirements.
(2)
The Contractor will be deemed to have made himself fully
aware of the nature and type of materials available and of
any steps to be taken to ensure that the requirements of the
manufacturer’s specification are met.
(3)
The Contractor shall carry work strictly in accordance with
this Specification and the approved method statements.
No variation from the Specification or method statements
are allowed unless approved by the Supervisor and
confirmation is obtained by the coating manufacturer.
(4)
Any unsatisfactory work or material shall be removed and
replaced by the Contractor at the Contractor’s own cost.
(1)
The two work components for the coating of concrete
surfaces are outlined as follows for the guidance of the
Contractor:
Work Components
29.10
(2)
(a)
Preparation of surface; and
(b)
Application of coating.
The application of coating shall be a continuous process as
much as practicable and subsequent coating of isolated
areas shall be avoided. Detailed requirements of each of
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Contract No. CV/2020/09
Particular Specification
Construction of Lei Yue Mun Public Landing Facility
the above components are specified in the following
Clauses.
PROTECTIVE COATING DETAILS
Surface
Preparation
Application of
Coating
29.11
29.12
(1)
Surfaces to receive the coating system shall be sound, free
from laitance, dust, loose debris, contamination (such as
oils and greases) and marine growth. Surface preparation
shall be such that the bond strength requirement of the
coating in accordance with the Model Specification can be
achieved.
(2)
The concrete surface shall be prepared by light grit-blasting
to remove all marine growth and contaminants to provide a
strong, hard surface.
Adequate protection shall be
provided to prevent damage from abrasive blasting to any
existing finishes on surfaces other than those designated to
receive coatings or to applied coating. Precautions shall
be taken to prevent damage to the existing structure.
(3)
Where necessary, areas of contamination shall be removed
by the use of appropriate solvent. The blasted surface
shall be thoroughly washed using high pressure water jet.
The prepared surface shall be left for one day to allow
defects to show up.
(1)
All liquid components shall be thoroughly stirred prior to
blending or application. Multi-component systems shall
be blended and mechanically mixed in accordance with the
manufacturer’s recommendations.
The batching and
mixing of multi-component mixes shall be in accordance
with the manufacturer’s recommendation. Part batches
shall not be mixed.
(2)
All equipment used for the application of coating materials
shall comply with the recommendations of the
manufacturer. These equipment shall be maintained in a
clean condition appropriate for next use.
(3)
The Contractor shall record and submit the batch number
of all protective coating used, and shall record and submit
against each batch number the location and extent of
reinforced concrete structures coated. Coverage rate shall
then be checked by the volume or weight of coating
materials and the area to be coated for compliance with the
stricter requirements of the manufacturer’s recommendation
or the designated coverage rate in PS Clause 29.13. The
Contractor shall also monitor the value and location of wet
film thickness of coating from time to time to ensure
compliance with the stricter dry film thickness (DFT)
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Contract No. CV/2020/09
Particular Specification
Construction of Lei Yue Mun Public Landing Facility
requirement of this Specification or the manufacturer’s
recommendation. These information shall be submitted to
the Supervisor on a weekly basis.
Pre-application
29.13
(4)
All surfaces shall be high pressure washed immediately
prior to coating application. At the time of coating
application, all concrete surfaces shall be clean with
moisture not exceeding the limits set by the coating
manufacturer. Under no circumstances shall coating be
applied to surfaces with standing water (including water
droplets) or during rain. The Contractor shall also
observe the relevant limits regarding ambient temperature
and relative humidity set by the manufacturer for coating
application.
(5)
Uneven surfaces must be leveled with a scratch primer or
leveling mortar as recommended by the manufacturer.
(6)
Spray equipment shall be used. All cleaning fluid shall be
purged from the equipment using undiluted coating
materials prior to application. All contaminated coating
materials used for purging equipment shall be discarded and
shall not be used in the works. Brush or roller techniques
shall not be used unless approved by the Supervisor.
When used, the brushes or roller heads shall be used for the
day only and then discarded. The equipment shall not be
re-used.
(7)
For multiple coat applications, the manufacturer’s stated
minimum and maximum overcoating times for the
prevailing weather and tidal conditions shall not be
breached. The maximum coating thickness shall not be
exceeded.
Alternate colours shall be adopted as
appropriate for multiple coat applications.
(8)
Between each coat application, the Contractor shall devise
and apply protective measures such as polythene sheets to
protect the coating surface from tidal water, dirt, oil or any
element that may adversely affect the bond of the
subsequent coat. In event of contamination, the surface
shall be washed off with clean fresh potable water prior to
application of further coats.
(9)
Where cracks have been repaired by resin injection or
where instructed by the Supervisor, the coating shall be
reinforced by an approved mat. The reinforcing mat shall
be applied subsequent to the first coat being applied. The
Contractor shall ensure that the reinforcing mat is fully
incorporated into the coating.
Prior to the application of any coating material, a pre-application
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Contract No. CV/2020/09
Particular Specification
Construction of Lei Yue Mun Public Landing Facility
testing shall be carried out according to the following steps :-
Testing
Testing
Requirement and
Frequency During
and after
Application
Table 29.01
29.14
(1)
The Contractor shall propose a testing area, on the marine
structure to be coated, of not less than 5m2 representative of
the coating area for approval by the Supervisor. The test
area shall be prepared according to PS Clauses 29.11 &
29.12. The complete coating system shall be applied on
this area in accordance with the manufacturer’s instructions
and the performance criteria of this Specification.
(2)
The actual consumption of the coating system per l/m2 shall
be recorded for the test area, in order that due allowance
may be made for rough, irregular or exceptionally
absorbent concrete.
(3)
After the coating system has been cured adequately, a test
of surface adhesion shall be carried out in accordance with
Appendix 8 of the Model Specification. The average bond
of 3 dollies to the concrete, via the completed coating
system, shall be satisfactory. A core sample shall be taken
from the test area for measurement of the DFT. Should
the minimum and mean DFT values of the core sample be
less than those specified, the coverage rates for the coating
system shall be proportionally increased for subsequent
applications.
(4)
Should the bond strength failed to comply with the stricter
requirements of this Specification and the manufacturer’s
recommendation, the test surface shall be re-prepared,
followed by re-application and re-testing in accordance
with steps (1) to (3) inclusively above.
(5)
Upon acceptance of the coating system by the Supervisor,
the actual consumption rate in (2) above or the coverage
rate adjusted in (3) above whichever more stringent shall be
taken as the designated coverage rate for actual coating
application.
(1)
The minimum testing requirements are listed in Table
29.01. Additional testing at no extra cost shall be required
when there are still doubts about the compliance with the
performance requirements.
(2)
All site tests and samplings shall be carried out by the
Contractor under the supervision of the Supervisor.
Test Requirements and Frequency
Test Required
Performed By
Standard
Frequency of Testing
Pre-qualification
of Materials
See PS Clauses
29.01 & 29.03
Model
Specification
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Contract No. CV/2020/09
Particular Specification
*
Construction of Lei Yue Mun Public Landing Facility
Bond Strength
*Approved
Laboratory
Model
Specification
(Appendix 8)
A rate of 1 sample set per 100m2 of
applied area or 1 sample set per pier
(whichever is the greater nos. of tests).
Each sample set shall consist of 3 cores
during the works at a location as
instructed by the Supervisor
Surface Finish of
Final Coat
Supervisor
---
All applied area to record any visual
defects on the coating surface.
Wet Film
Thickness of
Applied Coating
Contractor
Suitable
Instrument
approved by
the
Supervisor
1 measurement per 5m2 of coated area
to ensure achievement of the required
dry film thickness
Dry Film
Thickness of
Applied Coating
*Approved
Laboratory
Model
Specification
(Appendix 8)
A rate of 1 sample set per 100m2 of
applied area or 1 sample set per pier
(whichever is the greater nos. of tests).
Each sample set shall consist of 2 cores
taken during the works at a location as
instructed by the Supervisor
Laboratory to be proposed by the Contractor and approved by the Supervisor to carry out
the testing. The Laboratory shall have the required accreditation for the tests.
Acceptance
Criteria
Non-compliance
29.15
29.16
(1)
The DFT shall not be less than the value set by the
manufacturers.
(2)
The coating shall form a continuous film free from any
visible defects including but not limited to voids, pinholes,
blister, wrinkling and cracks.
Where the dry film
thickness fails the above test, the coating applied shall be
condemned. The Contractor shall remove, reapply all
area represented by the failed samples and retest at the
Contractor’s own expense accordingly.
(3)
The adhesion of the coating as measured not less than seven
days after application of the final coat shall be such that the
bond strength to the concrete substrate shall not be less than
1.0MPa. For multiple coat systems, the bond strength
between coats shall not be less than 1.0MPa.
(1)
The criteria for acceptance shall be the fulfillment of the
performance requirements of this Specification for all
sample sets/areas tested. In the event of non-compliance,
the Contractor shall, unless agreed by the Supervisor
otherwise :(a)
for failure of bond requirement, condemn, remove
and replace the coated area represented by the sample
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Contract No. CV/2020/09
Particular Specification
Construction of Lei Yue Mun Public Landing Facility
set yielding inadequate results.
(b)
for surface defects, rectify the defect/area by a
method approved by the Supervisor.
(c)
for failure of dry film thickness requirement, retreat
and re-test the area represented by the sample.
OTHERS
Contractors’
Attendance
29.17
The Contractor shall supply all labour, plant, materials and
assistance, including provision of safe access, equipment and
lighting, for the purpose of inspection and testing by the
Supervisor.
Making Good Test
Locations
29.18
All destructive test locations shall be made good and reinstated to
the profile and standard of the surrounding surfaces.
Submission of Test
Reports
29.19
The formal test reports for all quality testings shall be submitted
to the Supervisor within 2 weeks after testings being carried out
unless otherwise approved by the Supervisor.
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Contract No. CV/2020/09
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Construction of Lei Yue Mun Public Landing Facility
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