unkeyed, or deteriorated rock; all mud and silt accumulations; vegetation;
laitance; puddles or ponds of free surface water; coatings; and any other
detrimental materials. High-pressure water jetting, and/or wet
sandblasting, followed by mild high-volume, low-pressure washing, shall be
used on all hardened concrete surfaces (cold joints) as necessary for the
removal of laitance, coatings, stains, or other difficult-to-remove
contaminants. High-volume low-pressure water washing and/or water jetting
may be used for removal of loose materials. Adequate equipment with
operators shall be on hand at the site to clean all surfaces in conformance
with these specifications without disrupting in any way the RCC production
as scheduled.
3.2.6.2
High-Volume Low-Pressure Washing
Washing of loose materials can be accomplished with high-volume
low-pressure water washing and/or air water jetting using equipment of
similar design to that used in large-scale foundation cleanups. The
air-water jets shall have 40-mm 1-1/2-inch nozzles, a water supply of at
least 2 L/s 30 gpm, and compressed air at the jet of 550 to 850 kPa 80 to
120 psi. The low-pressure water jets shall have 25-mm 1-inch nozzles
available and a capacity of at least 13 L/s 200 gpm for truck-mounted
devices.
3.2.6.3
High-Pressure Water Jet
A stream of water under a pressure of not less than 10.3 MPa 1,500 psi for
RCC and 27.6 MPa 4,000 psi for conventional concrete shall be used for
cleaning all cold joint surfaces, or surfaces with laitance, mortar
coatings, stains, or other difficult-to-remove contaminants. There shall
be no undercutting of coarse-size aggregates. Aggregate particles that are
undercut shall be removed. For cleaning large open areas larger than
[_____] square meters feet, the high-pressure water jet system shall be
truck-mounted. For cleaning small or confined areas, the high-pressure
water jet system shall be portable.
3.2.6.4
Wet Sandblasting
This method may be used when the RCC has reached sufficient strength to
prevent undercutting of coarse aggregate particles. Wet sandblasting shall
be continued until all accumulated laitance, coatings, stain, or other
difficult-to-remove contaminants are removed. Wet sandblasting may be used
in lieu of or in combination with the high-pressure water jet.
3.2.6.5
Waste Disposal
Any waste water employed in cutting, washing, and rinsing of concrete
surfaces, and any other surface water shall not stain, or affect exposed
surfaces of the structure(s) or damage the environment of the project area.
Disposal shall comply with the provisions of Section [_____].
3.3
PLACING
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NOTE: Consult the concrete materials DM for the use
of optional sentences and filling in the blanks.
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SECTION 03701
Page 47
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