Unformatted text preview: from the prescribed
The surfaces of all forms in contact with the concrete shall be clean,
rigid, tight and smooth.
Suitable tleviccs shall be used to hold corners,
adjacent ends, and edges of nanels or other forms together in accurate
manently Metal forms or metal-lined
forms shall be permitted
exposed surfaces only when an entire surface is to
29 for perbe built IS : 457 - 1957
completely with such forms.
Curved and special forms shall be of a character
that would give smooth concrete surfaces.
They shall be so designed and
as not to warp or spring during erection or placing concrete.
Forms to be used more than once shall be maintained in, serviceable condition, and shall be thoroughly
clean and smooth before being Tensed.
Where metal sheets are used for lining forms. thr sheets shall be placed
on the forms with the minimum
amount of wrinkles,
bumps, or other imperfections.
The use of sheet m&l
tc) correct impcrfections in the lining of timber faced forms for surfaces that arc to bt* permanently exposed to view shall not be permitted.
\Vhcre ply\vood is used
for form lining, the joints between the sheets shall b(: smooth a11t1 as perfect as practicable,
and no patching of the plywood shall be permitted for
in the plywood shall
be corrected by the use of plastic wood, secured firmly in place and sandpapered smooth after it has hardened.
5.2 Absorptive Form bng
- Absorptive form lining, \vhcre directed
to be used, shall be of the type and quality approved l”y the engineer-inThe form lining shall be highly absorptive to ai:- and water, and
through its absorptive capacity be able to eliminate voids, pits and other
common defects from the concrete surface.
The lining shall he readily rcmovable from the concrete without damage to the surface.
It shall produce a dense co:lcmte
surface of uniform and satistactorv
The lining itself and any treatment
employed in its manufactttre
shall not discolour the concrete nor interfere
with the IJormal chemical
The backing to which absorptive lining is attached
reaction of the cement.
shall be sufficiently
smooth, even and free from cracks, knot’ holes, and
tci avoid unevenness
in the finished surface.
lining shall be ill sheets of uniform length and kvidth.
direction of the joints shall be approved by the tneitlccr-ill-charge.
joints between sheets shall be fitted smoothly and accurately. and patching
shall be avoided.
Edges shall be brought to light co11tact, t jut shall not be
Cutting and trimming shall 1)~ trut: and shall bc
pressed tightly together.
done with tools ~41 adapted to this work so that sharp, smooth, square
edges are produced.
Tl~e lining shall be attached to the forms in such a
Nails or tacks,
manner that it is held securely and smoothly
and shall be driven flush.
if used, shall be spaced in uniform. pattern,
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- Fall '13
- Bombay, Concrete Association, Concrete Section31 Committee, Concrete Subcommittee