Unformatted text preview: e used to break the fall and confine the flow.
The lower end of the spout shall be held close to the place of deposit.
Wherever depositing is intermittent, a discharge hopper shall be provided.
All chutes shall be thoroughly cleaned before and after each run. All
wash water and debris shall,be wasted outside the forms.
188.8.131.52 Pumping - ‘Zhere concrete is permitted to be conveyed
into place by the application of pressure, the pump and piping shall be
suitabty designed and shall be of adequate capacity ior the work. Pumping
shall be permitted only for conveying concrete containing aggregates less
than 7.5 cm ( or 3 in ) maximum size. The operation of the pumping
system shall be such that a continuous streAm of concrete, without air
pockets or interruptions, is delivered. At the end of the run, all concrete
remaining in the pipe line shall be rejected in such a manner as to avoid
any segregation or lack of uniformity. The pump and line shall be
thoroughly cleaned and al! *:;ash water and debris wasted.
184.108.40.206 Belt conveyors -Where
transportation by means of belt
conveyors is permitted, a steady, uniform flow of concrete shall be maintained without any segregation or piling up on steep inclines or at transfer
points. The conveyor shall be covered to prevent damage by rain, loss of
heat during cold weather, evaporation or heating by the direct rays of
the sun,,or’other deterioration of the concrete.
Concrete shall not be discharged directly into the forms, unless the
discharge end of the conveyor or pipe can be readily moved about within the
forms so as to place the concrete in even layers as specified under 4.10.2,
15 IS i 457 - 1957
Otherwise, suitable hoppers shall be provided, from which
the concrete shall be dumped in place by means of buckets and short
chutes or spouts.
4.8.3 Cleaning Epipment - At the end of each run and before again
placing any concrete, all hardened concrete or mortar shall be removed
from the inner surface of the conveying equipment.
All conveying equipment shall be maintained in good order and kept reasonably free from
deposits of stiff concrete and leakage of mortar.
4.9 Preparation for Placing Concrete 4.9.1 Before depositing any concrete for the ;lexC lift or pour, the
forms Shall not be retightened.
The surface of contact shall be allowed
’ to dry out between placing successive lifts of concrete.
The top of the
previously deposited concrete shall be thoroughly cleaned and prepared
as specified under 4.10.5.
220.127.116.11 Where new concrete is to be bonded to hard concrete, unless
otherwise ordered and in addition to the requirements specified under
4.105,. the vertical and inclined surfaces which cannot be covered with
mortar shall be given a heavy coat of neat cement grout, vigorously brushed
into all interstices and hollows so as to provide the best possible conditions
for bond and impermeability.
4.9.2 Rock Foundations -- All rock surfaces against which concrete is
to be placed shall be clean and free fr...
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- Fall '13
- Bombay, Concrete Association, Concrete Section31 Committee, Concrete Subcommittee