1.6.1
Cleaning
Equipment used in cleaning shall not cause staining, erosion, marring, or
other damage or changes in the appearance of the surfaces to be cleaned.
1.6.1.1
Sandblasting
Sandblasting equipment shall not be used in cleaning concrete and other
building surfaces; and shall be subject to approval for each other specific
applications. Sandblasting equipment permitted for use in cleaning
reinforcement and other embedded metal items shall include an air
compressor, hose, and long-wearing venturi-type nozzle of proper size,
shape and opening. The maximum nozzle opening shall not exceed 6.3 mm 1/4
inch. The air compressor shall be portable and shall be capable of
furnishing not less than 4.2 cubic meters 150 cubic feet per minute and
maintaining a line pressure of not less than 0.620 MPa 90 psi at the nozzle
while in use. The compressor shall be equipped with traps that will
maintain the compressed air free of oil and water. The nozzle shall have
an adjustable guide that will hold the nozzle aligned with the
reinforcement and other items to be cleaned, and will maintain the nozzle
approximately 25 mm 1 inch above the surface. The height, angle of
inclination and the size of the nozzle shall be adjusted as necessary to
provide satisfactory results. The Contractor shall provide protective
covers and barriers as required to prevent over-spray onto adjacent
surfaces.
1.6.1.2
Water Blasting
Water blasting equipment shall include a trailer-mounted water tank, pumps,
high-pressure hose, wand with safety release cutoff control, nozzle, and
auxiliary water re-supply equipment. The equipment shall not be operated
at a pressure which will cause etching or other damage to the concrete
surface, except for the surfaces of the interior of the excavation, where
operation at higher pressures may be used, subject to specific approval.
The equipment shall be operated at a discharge capacity of 0.38 MPa 55 psi
maximum and 9.5 to 11.4 L/minute 2.5 to 3 gpm for general surface cleaning
operations of the structure, and between 3.5 and 7 MPa 500 and 1000 psi and
9.5 to 11.4 L/minute 2.5 to 3 gpm for cleaning of drill holes and surfaces
of excavations. The water tank and auxiliary re-supply equipment shall be
of sufficient capacity to permit continuous operations. The Contractor
shall provide protective covers and barriers as required to prevent
over-spray onto adjacent surfaces.
1.6.2
Excavation
The equipment used to excavate concrete shall be handheld manual or power
type with a low-impact energy output and shall have gad points. The use of
chisel points is prohibited. Surface grinders for use in preparing
concrete and metal surfaces shall be small, hand-held equipment with a slow
to moderate operating RPM, using stone grinding wheels. Saw cutting
equipment shall use circular diamond blades. The blade shall be at least
3.2 mm 1/8 inch thick, with blade diameter selected as appropriate for the
application. Excavation equipment shall be subject to approval.
1.6.3
Equipment used to drill holes in concrete for patch anchors and other
applications shall be standard handheld masonry drills, commonly used for
drilling small holes in concrete and masonry. The drill shall be a small,
SECTION 03900
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