This item deals with a variety
of concrete treatments, including concrete surface sealing, horizontal crack
sealing, vertical crack sealing, and waterproofing.
For sealing of concrete
surfaces, the Contractor must use products from the Qualified
Product List (QPL) listed on the Office of Materials
Management’s (OMM) website for Epoxy-Urethane sealers
per C&MS 705.23A
and Non-Epoxy sealers per 705.23B.
For sealing concrete bridge
decks, the Contractor must use products on the QPL for High Molecular Weight Methacrylate (HMWM) Resin per 705.15,
for Soluble Reactive Silicate (SRS) per 705.24,
and Gravity Fed Resin per 705.25.
For sealing concrete cracks,
the Contractor must use products on the QPL for Epoxy Injection per 705.26.
For waterproofing concrete
surfaces, the Contractor must use products on the QPL for fabric and membrane material per the applicable
sections of 711
and for asphalt primers and sealers from the applicable sections of 702
and 705.
The Contractor must follow
the manufacturers’ recommendation for applying the sealer. Although spraying
methods allow for higher production rates and cover profiled surfaces more
easily than rollers, over –spraying must be contained and respirators and
personal protection will be required. The sealer is commonly applied with
rollers. When using rollers, brushes may also be required to apply the sealer
to bug holes and joints. The equipment
must be clean, free of contaminants, oil, and water.
The Contractor must mix the
sealer according to the manufacturer’s recommended procedures. Mixing paddles
must be jiffy type, not wire whips. The mixer should be run at 400 to 600 rpm
and be able to efficiently move the material for blending and not incorporate
air into the mix. Material should be mixed to a consistent color for not less
than three minutes.
Materials cannot be extended
or thinned. Improper mixing may cause poor or no hardening and inconsistent
color. Induction or rest periods impact the materials viscosity and pot life.
Do not use material beyond its pot life.
Figure 512.A
– Poorly Mixed Material
Figure 512.B
– Remnants of Material Applied Beyond Pot Life
The sealer needs to be stored
in a location where the temperature stays within the manufacturer’s recommended
range. It should not be stored in direct sun light or allowed to freeze. A
thermometer should be provided by the Contractor. Do not use material beyond its
shelf life.
Improper surface preparation
is one of the main reason we see sealer failures. When the sealer is applied to a damp, dusty,
or laitance laden surface, the sealer cannot gain the proper adhesion and will
peel off, normally in sheets.
Figure 512.C
– Sealers not Properly Bonded
All surfaces must be cleaned
of dust, dirt, oil, grease, wax, curing compounds, efflorescence, laitance, coatings,
and other foreign materials. All unsound areas should be repaired prior to
surface profiling. Patched areas should air dry for ten days prior to sealer
application. All concrete should attain its 28 day strength prior to sealer
application. Do not apply sealer to
joint sealants that have not cured to the manufacturers’ instructions. Check
for dust contamination prior to applying the sealer.
The purposes of surface
preparation are to remove dust, dirt, oil, grease, wax, curing compounds,
efflorescence, laitance, coatings and other foreign materials from the concrete
surface and to leave the concrete with an open, absorptive surface, exposing
the sand matrix of the concrete. The concrete surface which is to be sealed
should look and feel like 100 grit sandpaper or coarser (surface profile). An
inadequate surface profile will not provide the anchor pattern needed for
proper bonding. The Contractor is required to supply 100 grit
sandpaper for comparison.
If the concrete surface had
curing compound applied, the surface must be acid tested after blasting to
check if the curing compound was completely removed. Perform the acid test for
every 500 square feet.
1. Use a solution of one part 20 degrees Baume muriatic acid and two parts
water.
2. Apply four to five drops to the concrete surface. (If
foaming/fizzing occurs, the curing compound was removed).
3. If foaming/fizzing does not occur, use products
approved by the sealer manufacturer to remove the curing compound.
4. Rinse the tested location with an ammonia solution to
neutralize the concrete surface.
The manufacturers of the
sealer materials recommend the complete removal of existing coatings from the
concrete in order for their sealer to adhere to the concrete.
There is now a separate pay
item for the removal of existing coatings.
Figure 512.D
– Right Side of Barrier Properly Prepared
Figure 512.E
– Barrier after Surface Preparation
Surface preparation of
concrete surfaces can be done by water, abrasive blasting, or a combination of
both.
Water blast
at a 7,000 psi minimum. The
blasting equipment should have a gauge to verify the pressure.
Abrasive
blasting needs to be followed by air brooming or
power sweeping to remove dust and abrasive from the surface of the opened
pores.
Ensure all wastes from the
surface preparation operation are managed in accordance with C&MS 107.19.
The Contractor must control fugitive dust and waste water. They must contain,
collect, and properly dispose of all wastes.
Figure 512.F
– Containment for Blasting Debris Waste
Make sure the Contractor is
standing a reasonable distance away from the surface being blasted, typically
18 inches. Using a 7,000 psi water blast
from 6 feet away does not gain the level of cleanliness needed to correctly
apply the sealer.
Figure 512.G
– Combination Water/Abrasive Blaster
Figure 512.H
– Abrasive Blaster
If using water blasting
methods, the Contractor must apply the sealer between 12 and 48 hours after
surface preparation.
If using abrasive blasting
methods, the Contractor must apply the sealer within 48 hours after surface
preparation.
There must be no rain within 6
hours of sealer application. The ambient temperature must be above 50 ºF within
6 hours of sealer application. Time between coats shall meet manufacturer’s
written recommendations. Sealer must be applied at the approved coverage rate
in a continuous, unbroken film.
Epoxy-Urethane sealers must
be applied at the approved application rates listed on the Qualified
Product List (QPL) listed on the Office of
Materials Management’s (OMM) website. Application rate for Epoxy is 120 square feet
per gallon (150 square feet per gallon if authorized), for Urethane, it is 200
square feet per gallon. Application rates for sealers will vary for form liner
surfaces. Application areas should be marked to confirm coverage rates.
For sealed sidewalks, or
other non-skid horizontal surfaces, sand is broadcast and the sealer backrolled to encapsulate the sand.
Sags, runs, drips, holidays,
and discolorations are not acceptable.
Non-Epoxy sealers must be
applied at the manufacturer’s recommended mode of application. Do not apply
non-epoxy sealer if the ambient temperature is below 40 ºF or will fall below
32 ºF within 12 hours after application. Application rate for Non-Epoxy is 100
square feet per gallon for decks and sidewalks, 125 square feet per gallon on
vertical surfaces, and 150 square feet per gallon on parapets, abutments, pier
caps and median dividers.
These sealers are clear by
nature, but are to be tinted with a vanishing dye; therefore, it will be
difficult to see where progress ended on the preceding day. Establish a method to mark the stop point
that will not permanently be visible in the completed work.
Ensure that test sites
include a variety of surfaces:
horizontal, vertical, inverted, steel formed finish, troweled, floated,
rubbed, etc.
HMWM stands for High Molecular Weight Methacrylate.
If the Contractor supplies
3-part HWWM, which means the promoter, resin, and
initiator are supplied separately, be aware that the promoter and initiator
will react violently with each other.
This chemical reaction is so violent that these components normally
arrive to the job site on different trucks.
Poor surface cleanliness is a
major problem encountered in the field.
Dust and debris clog up the cracks and do not allow the HMWM to penetrate effectively. The temperatures of the concrete surface to
be treated must be the range from 50 ºF to 120 ºF. Do not apply the HMWM resin within 24 hours after rain or when rain is
forecast within 12 hours of application. The application rate should be
approximately 100 square feet per gallon.
Be sure to insist that the
Contractor coordinate his initial application on the project with the presence
of a manufacturer’s representative. This
representative should be a technical representative in lieu of a sales
representative.
The application of sand is
required to give the sealed surface a rough texture to assist with
traction. If the sand is applied after
the resin begins to harden, it will not become embedded and will merely brush
off with the first wave of traffic leaving a potentially slick surface.
Traffic should not be
permitted on the treated deck until it is tack free for a minimum of 6 hours.
There is a Qualified
Product List (QPL) for this material which is
maintained by the Office of Materials Management (OMM)
located under 705.15.
Proper surface preparation is
essential for SRS to perform properly.
The manufacturer’s representative must be on-site and sign off that the
surface preparation is adequate.
The Contractor is required to
perform a test section(s). This
section(s) should incorporate all of the surface types to be treated, since
test sections are to confirm application rates and appearance which will depend
on the orientation and porosity of the concrete.
The temperature of the
concrete surface to be treated must be above 35 ºF.
After the treatment has
cured, and prior to opening to traffic, the treated surfaces that experience
vehicular or pedestrian traffic should be washed down with water. In some instances, the SRS treated surfaces
have become very slick when first exposed to water. It is better to have this initial exposure in
a controlled scenario versus allowing the first water exposure to the surface,
such as rain, occur with traffic running on it.
There is a Qualified
Product List (QPL) for this material which is
maintained by the Office of Materials Management (OMM)
located under 705.24.
Proper surface preparation is
essential for Gravity Fed Resin to perform properly. Remove all dirt and debris
and all traces of asphalt or petroleum products from the deck to be treated.
The temperatures of the
concrete surface to be treated must be the range from 40 ºF to 100 ºF. Do not
apply the Gravity Fed resin within 24 hours after rain or when rain is forecast
within 12 hours of application. The application rate should be approximately
100 to 150 square feet per gallon.
Broadcast sand over the
sealed areas of the bridge deck by mechanical means.
Traffic should not be
permitted on the treated deck until it is tack free for a minimum of 6 hours.
There is a Qualified
Product List (QPL) for this material which is
maintained by the Office of Materials Management (OMM)
located under 705.25.
Epoxy Injection is a process
to repair cracks or fractures in reinforced concrete that are 2 to 100 miles
wide. Make sure the requirement for the presence of the manufacturer’s
representative is enforced even if the Contractor has vast experience with this
feature of work.
Note: The Contractor may
refer to the injection ports as “straws.”
The Contractor must establish
injection procedures and the depths and spacing of holes at injection ports or
tees. The Contractor must remove the injection ports or tees flush with the
concrete surface after the fracture has been filled and the epoxy has cured.
Take core samples as soon as the epoxy has cured. This is more critical on large jobs as the
method of epoxy injection may have to be altered if it is not achieving
adequate penetration. On small, one-day
type jobs, this will not be possible.
There is a Qualified
Product List (QPL) for this material which is
maintained by the Office of Materials Management (OMM)
located under 705.26.
Waterproofing material is
applied on vertical and horizontal concrete surfaces. The waterproofing needs
to be applied carefully to adhere to the concrete surfaces. Care should be
taken while placing backfill or paving against and over areas that have
received waterproofing. The
waterproofing can be damaged by either direct contact of the equipment or by
use of backfill materials which contain large sharp edged rocks. Do not apply
waterproofing fabric or membranes over attachments and hardware. Seal the
discontinuities with asphalt per C&MS 702.06
or hot applied joint sealer per C&MS 705.04.
Follow the manufacturer’s
recommendations for the application of prime coats, (rate of 0.10 to 0.20
gallon per square yard), prior to the application of fabric types, A, B, or C waterproofing. Follow the manufacturer’s recommendations for
the application of the Types 2 and 3 membrane waterproofing.
If asphalt pavement is to be
placed directly over the water proofing membrane, the Contractor must first
apply tack coat as specified in C&MS 407
without damaging the membrane.
There are Qualified
Product Lists (QPL) for the membrane and fabric
materials which are maintained by the Office
of Materials Management (OMM) located under 711.24,
711.25,
and 711.29.
1.
General.
a. Document type of material used (make and model).
b. Quantity of material used and application rate.
c. Area treated or sealed in square yards and/or lineal
feet of crack repaired.
d. Contact information for manufacturer’s representative
that is on-site (where required).
e. Atmospheric conditions and substrate temperatures.
2. Sealing of Concrete Surfaces (512.03)
(Use CA-S-21-
Sealing of Concrete Surfaces Checklist Form).
a. Copy of Superintendent’s Work Type 57 – Sealing of Concrete
Surfaces certificate (class taken within last 4 years).
b. Material Safety Data Sheet and application data from
Sealer Manufacturer.
c. Proper equipment for surface preparation (7,000 psi
minimum water blaster).
d. Concrete surface clean and free of all contaminants.
e. 100 grit sandpaper for surface preparation comparison.
f. Containment for blasting waste water and debris.
g. While stored, sealer not exposed to sun or frozen.
h. Proper mixing equipment.
i.
Document
atmospheric conditions and temperatures.
j.
Check application
coverage and rates. Document quantity of material used.
3. Waterproofing (512.08).
a. All surfaces clean and dry prior to placing
waterproofing.
i.
Type A, B, and D.
1. Amount of primer used.
2. Temperature of bituminous material.
3. Document amount of bituminous required and amount
used.
4. Document lap of fabric.
ii.
Type 2 and 3
membrane.
1. Temperature at time of application.
2. Document lap of membrane.
3. Type 3 surface joints sealed.