item
508 FALSEWORK AND
FORMS
508.01
Description
508.02 Falsework
508.03 Forms
508.04 Oiling
Forms
508.05 Basis of
Payment
508.01 Description. This work consist of
designing and building of falsework and forms for the
purpose of holding concrete in place until it has set up.
508.02 Falsework. Provide
substantial and rigid falsework that does not unduly
obstruct any waterway, highway, or railway. Arrange intermediate supports
in the completed structure to produce the camber necessary to conform to the
plan profile of the roadway.
Do
not allow the maximum deflection in the longitudinal falsework
members at the edges of the concrete deck to exceed 1/2 inch (13 mm) or the
amount obtained by the following formula, whichever is greater.
Where:
d = the maximum deflection in inches
(millimeters)
S = the distance between supports in inches
(millimeters)
For
transverse falsework members, and for longitudinal falsework members other than those near the edges of the
deck, increase the permissible deflection obtained from the above formula by 75
percent.
To
compensate for falsework deflection, build camber
into the falsework. In addition to falsework defection, build the following amounts of camber
into the falsework to compensate for slab deflection
after falsework is released:
A. Equal to 1/800 of the span for
continuous spans.
B. Equal to 0.000018 S3 (0.016 S3) for
simple spans, where S is the length of the slab span in feet (meters) for
camber expressed in inches (millimeters).
Provide
camber to conform to the profile grade.
If
the falsework does not rest in rock, shale, or other
firm foundation material, support falsework on piling
driven to sufficient penetration to carry the superimposed loads according to
Item 507, but not less than 16 tons (16 metric tons) per
pile. Perform dynamic load testing to determine required blow count if
piles are not driven to rock. Do not use expansion anchors to support falsework on piers or abutments. Use double hardwood
wedges as necessary to facilitate vertical adjustment.
Remove
and replace any part of the structure made unsatisfactory by incorrect camber,
settlement or form deformation.
Construct
falsework for arches so it may be released gradually.
Remove
falsework only after the concrete conforms to 511.16 and before final acceptance of the
structure. Cut off or pull falsework
piling. Cut off piles to at least the slope line, riprap line, or stream
bed.
Locate
the lower contact point of overhang falsework within
8 inches (200 mm) of the top of the rolled beam or steel girders bottom flange.
Submit
falsework plans for cast-in-place concrete slab
superstructures according to 501.05.
If
a thickened edge is shown on the plans, the Contractor may develop the edge by sloping the bottom of the slab for a minimum of 9 feet (2.7
m) from the edge, instead of the section shown.
Do
not place spandrel walls, decks of arches, sidewalks and curbs, or any superimposed
concrete to be completed after constructing the main supporting member or the
deck until the falsework for the main supporting
member has been removed or released.
For
continuous concrete slab or beam superstructures, do not place concrete on a
span until the falsework and forms are complete for
the adjacent spans. Do not release or remove falsework
from a span until the concrete in adjacent spans has been placed a sufficient
length of time to meet all requirements for the removal of falsework
as set forth in 511.16.
508.03 Forms. Place all concrete in proper
forms. Do not use unprotected sides of the excavation, instead of forms,
unless as specified in 503.04 for rock or shale
excavation. For dry excavation specified in 503.03,
the Contractor may use the sheeting as forms for footings.
Construct
substantial, unyielding, and mortar tight forms, designed to produce a finished
concrete conforming to the proper dimensions and contours. Make forms for
exposed surfaces of approved material requiring a minimum number of joints or
of dressed lumber of uniform thickness using form liner approved by the
Engineer. Use forms and form liners to reduce the joints showing on the finished
surface to a minimum. Arrange joints to coincide with rustication grooves
shown on the plans. Properly brace or tie forms together using approved
form ties that do not allow metal within 2 inches (50 mm) of an exposed surface
of the finished structure after the forms are removed. For ties in the
region of exposed surfaces, use an approved insert. Remove all forms and
do not allow material, except reinforcing supports specified in 509.08, to remain in the concrete.
In
forming pier, intermediate, or end diaphragms for prestressed
or post-tensioned concrete members, do not damage reinforcing steel, strands,
or precast concrete in the placement of post installed anchors in these
members. Properly brace diaphragm forms externally or use approved form tie
inserts cast into these members.
For concrete
decks separated by an open median or temporarily separated by a closure
section, construct falsework and forms for each deck
or section of deck independent of the adjacent structure or remaining
superstructure.
Immediately
before placing concrete, provide temporary openings at the base of column and
wall forms and in the bottom of all narrow, deep members where necessary to
facilitate cleaning or inspection.
Provide
a 3/4-inch (20 mm) bevel on all exposed edges using a triangular strip built
into the forms.
If
rustication is used, fasten molding that is surfaced on all sides to the forms
in such a manner that the molding remains in the concrete when the forms are
removed. Do not remove this molding until the concrete has set
sufficiently to prevent damage to the edges of the concrete.
If
weep holes through abutments or retaining walls are shown on the plans, form
weep holes to obtain a smooth circular opening between 3 and 4 inches (75 and
100 mm) and a straight gradient of 0.08 through the wall.
508.04 Oiling Forms. Before
placing reinforcing steel, coat the inside of forms with non-staining mineral
oil or other approved material.
508.05 Basis of Payment. The
Department will not separately pay for falsework and
forms. The cost of this work is included for payment in the price bid for
the item for which falsework and forms are used.
The
Department will not pay for removal and replacement of any part of the
structure made unsatisfactory by settlement or form deformation.
The
Department will not pay for dynamic load testing required to determine blow
count if piles are not driven to rock.