hammering of the rib at designated intervals and
alternating directions.
c. Acid etch finish - produced by treating the
surface of unit with brushes which have been
immersed in acid solution. Surface sealers or
coatings are generally not recommended. The
designer should consult ACI 303 and PCI MNL-117
before specifying sealers or coatings.
**************************************************************************
2.2.6.1
Exposed Surfaces
Surfaces of precast units exposed to view or surfaces indicated to be
finished shall be finished as follows: [_____].
2.2.6.2
Other Surfaces
Surfaces of precast units not exposed to view or not otherwise indicated to
be finished shall be finished in accordance with Section 03300A
CAST-IN-PLACE STRUCTURAL CONCRETE.
PART 3
EXECUTION
3.1
ERECTION
Precast units shall be erected in accordance with the detail drawings and
without damage to other units or to adjacent members. Units shall be set
true to alignment and level, with joints properly spaced and aligned both
vertically and horizontally. Erection tolerances shall be in accordance
with the requirements of PCI MNL-117 and PCI MNL-122. As units are being
erected, shims and wedges shall be placed as required to maintain correct
alignment. After final attachment, precast units shall be grouted as
shown. After erection, welds and abraded surfaces of steel shall be
cleaned and touched-up with a zinc-rich paint. Welds shall be made by a
certified welder in accordance with the manufacturer's erection drawings.
Pickup points, boxouts, inserts, and similar items shall be finished to
match adjacent areas after erection. Erection of precast units shall be
supervised and performed by workmen skilled in this type of work. Welding
and the qualifications of welders shall be in accordance with AWS D1.1/D1.1M.
3.2
JOINT SEALING
Joint sealing shall be as specified in Section 07920 JOINT SEALANTS.
3.3
CLEANING
Not sooner than 72 hours after joints are sealed, faces and other exposed
surfaces of precast concrete discolored during erection shall be cleaned to
remove dirt and stains by dry scrubbing with a stiff fiber brush, wetting
the surface and vigorous scrubbing of the finish with a stiff fiber brush
followed by additional washing, or by chemical cleaning compounds such as
detergents or other commercial cleaners. Commercial cleaners shall be used
in accordance with the manufacturer's recommendations. Cleaning procedure
shall be performed on a designated test area and shall be approved prior to
proceeding with cleaning work. Discolorations which cannot be removed by
these procedures, will be considered defective work. Cleaning work shall
be done when temperature and humidity permit surfaces to dry rapidly.
Adjacent surfaces shall not be damaged during cleaning operations.
SECTION 03413A
Page 11
Previous Page
