DRAFT
Preston Beach Weymouth
Sealant replacement and slab repairs
Environment Agency
Wessex South Area Operations Delivery
Technical Support
Specification
28th May 2012
Project: Preston Beach Weymouth, Dorset, DT4 7SX
Sealant replacement and slab repairs
INTRODUCTION
THIS SPECIFICATION refers to joint sealant replacement and slab edge repairs to the sea
defence wall and service road at Preston Beach, Weymouth, Dorset, DT4 7SX.
This structure is of reinforced concrete construction and is approximately 15 years old.
A recent inspection has identified failure of joint sealants and damaged slab edges.
This specification should be read in conjunction with all other contract documents.
All materials for this specification shall be pre-packed products supplied in original, sealed
containers and within recommended shelf life for the storage conditions pertaining.
The materials shall come from the containers as supplied be mixed as necessary and shall
be used in prepared areas in accordance with current data sheets and instructions for use
and by method(s) approved by the Project Manager.
It is the responsibility of the product user to ensure that all the latest information is to hand,
and that product instructions for use, safety procedures, etc., are understood and followed
exactly.
BS EN ISO 9000: The manufacturer of all such products shall be a BSI registered firm of
assessed capability for Quality Assurance to BS EN ISO 9001.
COSHH Safety Data Sheets in the mandatory 16-section format are included to comply with
the current regulations for all products covered by this Specification.
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Project: Preston Beach Weymouth, Dorset, DT4 7SX
Sealant replacement and slab repairs
Index
Item Subject
Page no.
1
Schedule of materials
4
2
Concrete repairs with formulated mortar – preparation of concrete
and steel reinforcement
6
3
Rapid setting deck/pavement repair mortar
9
4
High strength epoxy repair mortar
11
5
Closed cell polyethylene filler
14
6
2-part polysulphide sealant
15
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Project: Preston Beach Weymouth, Dorset, DT4 7SX
Sealant replacement and slab repairs
1
SCHEDULE
PRODUCT
PROJECT
REFERENCE
SPECIFICATION
SECTION
Nitobond EP or
equal approved
To be used to bond the rapid setting
cementitious mortar to the substrate
(existing concrete slab).
Epoxy resin concrete
bonding agent
Patchroc GP or
equal approved
To be used when the repairs in the
service road are more than 25mm deep.
Concrete repair with
formulated mortar.
A saw cut is required around the joint.
The nosing to the joint should be slightly
rounded to reduce the impact damage
caused by wheels.
Rapid setting
deck/pavement repair
mortar for repairs over
25mm thick
Nitobond AR or
equal approved
To be used as a curing agent for the
rapid setting cementitious mortar.
See datasheet
Nitomortar S or
equal approved
To be used when the repairs in the
service road are less than 25mm deep.
Concrete repair with
formulated mortar.
A 5mm saw cut is still required and
again the nosing should be slightly
rounded.
High strength epoxy mortar
repair for repairs under
25mm thick
Nitoprime 25 or
equal approved
To be used as a primer for the substrate
(existing concrete slab) before applying
the high strength epoxy mortar.
2 part epoxy primer
High strength epoxy mortar.
Nitoprime zincrich
plus or equal
approved
To be used as a primer for any
reinforcement exposed when breaking
out defective slab concrete and before
replacing with mortar.
Concrete repair with
formulated mortar.
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Project: Preston Beach Weymouth, Dorset, DT4 7SX
Sealant replacement and slab repairs
Expandafoam
Cord or equal
approved
To be inserted into joint gap to provide
support for the joint sealant. Depending
on the depth in the road joints more
than one layer of cord may be required.
Closed cell polyethylene
joint filler
Thioflex 600 or
equal approved
To be used to replace all defective
sealants in road and sea wall. Typically
road joints should be recessed 5mm
from the surface to reduce foot and
wheel contact. A judgement on the
recess depth is required depending on
the time of year and the thermal
movement that can be taking place.
Two part polysulphide
sealant
Primer 7 or equal
approved
To be used as a primer for the substrate
(existing concrete slab edges) before
applying the sealant
See data sheet
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Project: Preston Beach Weymouth, Dorset, DT4 7SX
Sealant replacement and slab repairs
2
CONCRETE REPAIRS WITH FORMULATED MORTAR
PREPARATION OF CONCRETE AND STEEL REINFORCEMENT
Repair Areas
The areas to be repaired are to be as shown on the drawings or as indicated by the Project
Manager. The areas are to be clearly marked out on site and agreed with the Project
Manager before proceeding.
A clear indication of maximum permitted depth, and area of existing concrete which may be
removed at any time, shall be provided by the Project Manager.
The areas may be adjusted by the Project Manager as work proceeds according to the
conditions found.
The volume and dimensions of the void for repair shall be in accordance with the design
criteria for the reinstatement material.
Propping shall be provided as noted on the drawings or as agreed by the Project Manager.
Areas for repair, and adjacent surfaces, shall be cleaned to remove any dust, unsound
material, plaster, oil, paint, grease, corrosion deposits, organic growth, etc.
Concrete Preparation
The equipment and methods used to break out the concrete shall be such that no reinforcing
steel or other embedded items such as conduits or lifting sockets, etc., are loosened,
damaged or removed, unless so directed by the Project Manager.
If reinforcement is found to be congested, making difficult the removal of concrete by
mechanical means, then high pressure water jetting shall be considered and a necessary
provision for protecting the rest of the structure shall be allowed for.
The prepared void shall be profiled so that entrapment of air during the process of placing the
repair material is avoided.
Break out unsound concrete as defined within the repair zone. Using a saw, disc cutter, or
other suitable tool, the perimeter of the area to be repaired shall be cut out to a depth to suit
individual mortar specifications, causing good arrises to be formed at the outer edges all to
preclude feather edging of the repair mortar.
Where the depth of breaking out corresponds to the depth of concrete cover and thereby
exposes corroded reinforcement, work should stop until the Project Manager has agreed to
this additional work.
If agreed with the Project Manager, breaking out shall continue to expose the full
reinforcement length. Breaking out shall continue along the reinforcement until non-corroded
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Project: Preston Beach Weymouth, Dorset, DT4 7SX
Sealant replacement and slab repairs
steel is reached and shall continue 50 mm beyond this point. Special care shall be exercised
to ensure that any reinforcement exposed is not cut or damaged.
All concrete surfaces to receive repair mortar shall be of a rough scabbled nature. Saw/disc
cut edges shall be grit blasted to lightly roughen.
This preparation shall be such as to leave a sound exposed concrete substrate free from
dust, loose particles and any deleterious matter.
Reinforcement Preparation
All exposed reinforcement should be cleaned in accordance with the primer data sheet.
When the corrosion products have been removed, and if directed by the Project Manager, the
diameter of the reinforcing bar(s) shall be measured. If considered necessary by the Project
Manager the existing reinforcement shall be cut out and replaced and/or additional bars
added in accordance with instructions. Any deep pitting of the reinforcing bars shall be
brought to the attention of the Project Manager.
Reinforcement damaged during the removal of concrete or the preparation process shall be
brought to the attention of the Project Manager and if required, shall be repaired or replaced.
The steel reinforcement shall be primed immediately following preparation and cleaning.
Reinforcement Primer
When required, the steel reinforcement primer shall be NITOPRIME ZINCRICH PLUS or
equal approved, a single-component zinc-rich liquid, packed and supplied ready to use and
capable of providing the following properties:
The primer shall:
1)
Be an unbroken 40 micron (dft) coating forming an impervious barrier.
2)
Be of suitable viscosity to enable it to penetrate imperfections and pits in the surface of
corrosion-damaged steel bars and shall be fully compatible with the repair mortar
system;
3)
Be such that drying occurs to allow the application of the repair mortar to proceed after
90 minutes at 20oC.
Reinforcement Priming
The zinc-rich primer shall be brush applied to the cleaned reinforcement at a thickness of 100
microns (wft), ensuring that all exposed steel is fully coated, paying special attention to the
backs of the steel bars and where steel bars are tied together. This coat shall be continuous
with any adjacent repaired area where zinc-rich primer has been used. Excessive
overpainting onto the concrete shall be avoided and the coating allowed to dry.
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Project: Preston Beach Weymouth, Dorset, DT4 7SX
Sealant replacement and slab repairs
Epoxy Resin Concrete Bonding Agent
The epoxy resin concrete bonding agent shall be Nitobond EP or equal approved.
Preparation
All surfaces to be treated should be mechanically prepared (scabble or grit-blast) to expose
aggregate and all debris and dust removed. Oil and grease deposits should be removed by
steam cleaning, detergent scrubbing. Exposed fully any corroded steel and remove all loose
scale and corrosion deposits. Steel should be cleaned to a bright condition paying particular
attention to the back of exposed steel bars. Grit blasting is recommended for this process.
Reinforcing steel priming
The cleaned steel should be coated within 3 hours. Apply one full coat of reinforcement
primer and allow to dry before continuing.
Mixing
The contents of the base and hardener cans of the bonding agent should be stirred
thoroughly to disperse any settlement. The entire contents of the hardener can should be
added to the base container and mixed thoroughly for at least 3 minutes until a uniform colour
is obtained.
It is recommended that mechanical mixing be employed; using a Jiffy mixer on a heavy duty,
slow speed electric drill.
To facilitate application at temperatures below 10 ºC the separate components should be
warmed in hot water to maximum of 25 ºC before mixing. However, the mixed material will
need to be used speedily as the pot life of the standard grade will be reduced to 20 minutes.
Application
The thoroughly mixed material should be applied with a suitable stiff nylon-type brush and
must be firmly scrubbed into the surface, ensuring an even coating. The new concrete or
screed should be applied over the bonding agent within 1½ hours at 20 ºC, or within 1 hour at
30 ºC.
Alternatively a slower setting bonding agent such as Nitobond EP slow set or equal approved
can be used to allow for application prior to the fixing of shuttering or reinforcement.
Cleaning
Tools and equipment should be cleaned with a suitable solvent immediately after use.
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Project: Preston Beach Weymouth, Dorset, DT4 7SX
Sealant replacement and slab repairs
3
RAPID SETTING DECK/PAVEMENT REPAIR MORTAR
For repairs more than 25mm thick
The floor repair mortar shall be PATCHROC GP or equal approved; a cementitious rapid
setting, shrinkage compensated, cementitious premix pavement patching compound. Use in
conjunction with an epoxy bonding agent in heavily trafficked areas.
The floor repair mortar shall comply with the classification R4 according to EN 1504-3, repair
methods 3.2, 4.4, 7.1 and 7.2
It shall be capable of providing the following properties:
1)
Compressive strength at 2 hours of 20 MPa, at 1 day of 50 MPa and at 28 days of 65
MPa.
2)
Modulus of elasticity in compression at 28 days of 29 MPa.
3)
Bond strength by pull off of 2.2 MPa.
4)
Adhesive bond after freeze thaw cycling of 2.0 MPa.
5)
Chloride ion content of 0.02%.
6)
Resistance to carbonation penetration dk ≤ reference concrete.
Use
Edges of concrete slabs to be repaired shall present an edge strip cut out to a minimum
depth of 25 mm and cut back by a minimum of 50 mm. The length of repair strip may be less
than 0.5 m but shall not greatly exceed 0.5 m. Temporary edge support is needed.
Priming Concrete (bonding agent)
Prime using an epoxy-resin concrete bonding agent such as NITOBOND EP standard or
equal approved. The bonding agent should be mixed and applied in accordance with the
manufacturers instructions. The repair mortar should be applied to the bonding agent within
1½ hours at 20oc.
Mixing
Before mixing the patching compound the contractor shall ensure that sufficient and correct
areas for reinstatement are prepared and ready to receive patching compound.
Only mixes using one complete bag of rapid setting mortar shall be allowed and part bag
mixes not permitted
The mixing shall be carried out strictly in accordance with current product instructions for use
and only with appropriate mixing equipment.
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Project: Preston Beach Weymouth, Dorset, DT4 7SX
Sealant replacement and slab repairs
The mixing water shall be potable quality and the carefully measured quantity of water for the
mix shall be placed into the mixing container before the rapid setting mortar.
Application
Only fully integrated mixes of rapid setting mortar at the required consistency and workability
shall be used.
Apply the mixed rapid setting mortar to the primed substrate as soon as possible after mixing.
The mortar should be applied evenly by trowel and tamped in place with a wood float to
ensure full compaction. Thoroughly compact the mortar around any exposed steel
reinforcement. The rapid setting mortar shall be able to be applied from a minimum of 25mm
to a maximum of 100 mm thickness in one application. The maximum bay size should be
4m2.
Thicker sections may be applied by the addition of graded silt free aggregate. For details
regarding application at a pourable consistency, for vertical applications and on horizontal
sections between 100 and 250 mm contact the supplier for further information.
On attaining the correct level, the surface shall be finished by striking off and closing with a
steel trowel, or textured with a roller or sweeping brush, in accordance with the requirements
of the Project Manager.
Where formwork is used e.g. slab edges, it shall be pre-treated with a varnish and release
coating to prevent moisture absorption from the repair compound.
Curing
Details of the methods of curing shall be submitted to the Project Manager for approval.
Curing of the finished surface of each mix shall commence immediately following laying. A
suitable low-pressure spray curing agent such as Nitobond AR or equal approved may be
applied as a curing membrane. In fast drying conditions it will be necessary to supplement
this with polyethylene sheet taped around its edges. Prior to final set the rapid setting mortar
shall be protected against heavy rainfall, exposure to heavy rainfall prior to the final set may
result in surface scour. In winter the finished surface shall be protected against frost for the
first three days.
Limitations
The rapid setting mortar should not be used when the temperature is below 5 oC and falling. It
should not be exposed to moving water during application or totally immersed in water for the
first 24 hours after application.
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Project: Preston Beach Weymouth, Dorset, DT4 7SX
Sealant replacement and slab repairs
4
HIGH STRENGTH EPOXY REPAIR MORTAR
For repairs less than 25mm thick
The high strength repair mortar shall be NITOMORTAR S or equal approved, a three
component epoxy resin:
The cured mortar shall achieve a compressive strength of 70N/mm², a flexural strength of
20N/mm² and a tensile strength of 10N/mm², when tested at 7 days. The water absorption of
the cured mortar shall not exceed 0.2% and the density be no greater than 2015kg/m 3.
The minimum application thickness of this mortar shall be 5mm.
Work Area
Avoid inhalation of vapours and ensure adequate ventilation.
breathing apparatus shall be worn.
In confined areas suitable
Additional Preparation Considerations
Using a saw, disc cutter or other suitable tool the perimeter of the area to be repaired shall be
incised to a depth of at least 5mm causing good arrises to be formed at the outer edges all to
preclude feather edging of the repair mortar.
Priming Concrete
The concrete primer shall be NITOPRIME 25 or equal approved.
The entire contents of the Hardener tin shall be added to the Base tin and be thoroughly
intermixed. The mixed primer shall be brushed well into the prepared surface ensuring
complete coverage and no pools of collected material. If the primer is absorbed within 30
minutes, then a second coat shall be applied.
Single repair/render areas larger than 0.5m² shall be part primed to commence and thereafter
in bays to suit chequerboard application of the high strength epoxy mortar.
The high strength epoxy mortar shall be applied when the primer has started to gel, but the
surface is tacky - ½ to 4 hours, depending upon temperature.
If the primer dries before the mortar is applied, the area shall be reprimed.
Mixing Epoxy Mortar
Before mixing the epoxy mortar the contractor shall ensure that sufficient and correct areas
for reinstatement are prepared and ready to receive epoxy mortar.
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Project: Preston Beach Weymouth, Dorset, DT4 7SX
Sealant replacement and slab repairs
Only mixes using complete packs of high strength epoxy mortar shall be allowed and part
pack mixes not permitted.
The mixing shall be carried out strictly in accordance with current product instructions for use
and only with appropriate mixing equipment. The high strength epoxy mortar shall be mixed
by hand if "Standard Pack" or mechanically mixed if "Industrial Pack".
The complete contents of the Base and Hardener shall be emptied into the mixing container
and mixed thoroughly. The aggregate shall then be added and the three components
blended together, ensuring that the aggregate is thoroughly wetted out with resin.
Application of Epoxy Mortar
Application shall commence immediately following mixing.
Only fully integrated mixes of the high strength epoxy mortar shall be used and within the
mixed-state life of 45 minutes.
Apply the high strength epoxy mortar to the primed surface with a wood float, pressing firmly
into place to ensure positive adhesion and paying particular attention to packing behind and
between any reinforcement and even compaction overall.
Any areas for treatment, which are more akin to rendering, such as large shallow
indentations, or surfaces being treated for chemical resistance, shall be treated chequerboard
fashion, 0.5m² at a time. These areas shall be treated so that 8 to 24 hours is allowed
between abutting epoxy mortar edges and all edges shall be primed together with the
concrete.
The high strength epoxy mortar shall be applied in accordance with current instructions for
use. It may be applied in one operation by building up to the required profile in wet-on-wet
layers between 5-25mm
Sagging of the repair mortar is not acceptable and if occurring all the material of the affected
repair shall be completely removed prior to repriming and refilling in two or more applications
of mortar supported by formwork if required.
If formwork is used it shall be pretreated with a varnish. Special care shall be taken to ensure
that the positioning of the formwork allows for even placing and does not result in voids within
the repair mortar. The surface of the formwork shall not be coated with the primer. It shall be
struck shortly following application of the repair mortar, before hardening of the surface.
After applying sufficient mortar to achieve a level flush with the surrounding surface the high
strength epoxy mortar shall be finished by closing with a steel trowel.
Temperature
At 20oC the initial hardness of the high strength epoxy mortar occurs approaching 24 hours
and the full cure is at 7 days. Below 20 oC the curing time increases and the minimum
application temperature is 5oC.
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Project: Preston Beach Weymouth, Dorset, DT4 7SX
Sealant replacement and slab repairs
In cold weather the high strength epoxy mortar and the primer should be stored in warm
conditions. Dependent upon conditions it can be helpful to tent the work area, also to warm
the work piece immediately prior to priming and application of the mortar.
New work shall be protected against frost until hard and resistant.
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Project: Preston Beach Weymouth, Dorset, DT4 7SX
Sealant replacement and slab repairs
5
CLOSED CELL POLYETHYLENE JOINT FILLER
Closed cell polyethylene joint filler for use as an expansion joint filler in brick and blockwork,
isolation joints and hinge joints where a readily compressible low load transfer joint filler is
required, for example Expandafoam or equal approved.
Strip and cord sections are also available. These are used as back up strips for elastomeric
sealants.
The joint filler/back up strips shall be Expandafoam or equal approved. Whether in sheet
form or in strip or cord form, the joint filler shall be installed strictly in accordance with the
relevant technical data sheet. The joint filler shall have a density of 30 +/- 5kg/m2 and a
recovery greater than 70%.
Application
The joint filler sheets may be fixed into position using a suitable adhesive such as Supastik
wall panel or contact adhesive. Care should be taken not to contaminate the surfaces of the
sealing slot with adhesive.
Where Expandafoam is used as the joint filler no additional bond breaker is necessary.
Used as a back up/bond breaker strip, the joint filler shall serve both to regulate the depth of
the sealing slot required and to ensure that the movement of the joint sealant is not restricted
by three sided adhesion.
The size of the back up strip should be approximately greater than the joint width and
depressed sufficiently to provide the required sealing slot dimensions. Circular cord sections
provide a convex face giving an optimum seal configuration, they also overcome any problem
of twisting which can occur with square or rectangular sections.
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Project: Preston Beach Weymouth, Dorset, DT4 7SX
Sealant replacement and slab repairs
6
TWO-PART POLYSULPHIDE SEALANT
Sealant
Joints shall be sealed using THIOFLEX 600 or equal approved, a two-part polysulphide
sealant, manufactured to BS4254: 1983.
The sealant shall have a Movement
Accommodation Factor of 25% (butt joints); a 100% solids content and a density in the range
1.62 to 1.73 kg/litre.
Use
The sealant shall not be used in contact with materials containing pitch or bitumen.
Where new surface coating and new joint sealing work coincide, the surface coating shall be
completed first and be dry throughout, before sealant application.
Joint Preparation
The joint surfaces shall be thoroughly dry, clean and frost free. All dust, laitance, old sealant,
etc, shall be removed by rigorous wire brushing, grinding or grit blasting. All rust, scale and
protective lacquers shall be removed from metal surfaces. Remove any oil or grease with a
suitable joint cleaner.
Any expansion joint filler shall be checked to ensure it is tightly packed and no gaps or voids
exist at the base of the sealing slot, before positioning a bond breaker.
The use of a bond breaker shall not be required in expansion joints containing cellular
polyethylene expansion joint fillers such as Expandafoam. For construction or contraction
joints a bond breaker or back up tape shall be used.
Any coating which may be on joint faces, shall be removed, carefully, ensuring no damage to
the coating on the arris.
Where a particularly neat finish is required, the face edges of the joint shall be masked using
low adhesive capacity tape before priming and the masking removed immediately after
sealant has been installed and tooling is completed. Any masking tape used on a coating
surface shall be of low adhesive capacity and trailed to ensure that the coating is sufficiently
mature to withstand application/ removal of the tape.
Priming Requirements
A one-part chemically active clear liquid primer for polysulphide sealants for brush application
to porous surfaces, such as PRIMER 7 or equal approved, shall be used on the edges of the
concrete slab before applying the sealant. One thin coat shall be applied and allowed to dry
until tack free (normally 20 minutes to 3 hours), before sealing. Excessively porous surfaces
may need more than one coat.
A clean, dry brush shall be used to ensure complete coverage. Priming resulting in an
excess of primer in the base of the joint or application beyond the joint faces shall be
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Project: Preston Beach Weymouth, Dorset, DT4 7SX
Sealant replacement and slab repairs
avoided. The mixed sealant shall be applied when the primer is tack free, i.e. after the
evaporation of the solvent but before the primer film has completely reacted. If the sealant is
not applied before 3 hours, then the surfaces shall be re-primed.
Finishing
The joint sealant shall be tooled to a smooth finish. A minimum of surface lubricant such as
dilute detergent solution or white spirit may be used to assist the process. Any masking tape
shall be removed immediately after tooling.
Maintenance
No special requirement, however, physical damage shall be repaired if and when it occurs.
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