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188.8.131.52 The USC of flexiblr shaft vibrators,
closely follow special instructions
issud for tt!c purpose. shall 184.108.40.206 Internal vibrators shall be allowed to penetr;ltcB as deeply
as possible under their own weight and shall so consolidate fhe succcssivc
layers as to break up effectually all- strata or seams.
The vibrators shall
be inserted and withdrawn slowly in such manner as not to leave voids in
the plastic concrete.
The entire operation shall be condncted in a systrmatic manner and each course or layer vibrated uniformly.
of dumping or depositing the loads shall be so arranged as to keep the
during placing operations.
shall be kept approximately
l+el, and the concrete. even when depdsited
in thin layers, shall be as st;iI as can be satisfactorily
concrete for which a slump greater than 10 cm ( or 4 in ) is specified shall
not be vibrated unless otherwise ordered.
Care shall be taken ndt to
disturb a set of partially set layer.
The vibrators shall be held vertical
as far as possible.
220.127.116.11 Under no conditions shall internal vibrators strike the face
of the forms, nor shall reinforcement
steel or embedded metal be jarred
with sufficient force to impair the bond between the concrete gnd the
4.11.4 Ex&c7nul Tybe Vibmtors 18.104.22.168 Whereyer so required.
shall be used
to embed all large stone or cobblblc projecting above the top of the lift, but
such vibrators shall be used with caution and operated only in such manner
as to avoid pulling exccjs mortar to the surface. The entire top of the lift
for a depth c;i about 30 cm ( or 1 ft ) shall be thoroughly vibrated.
Particular care s.lall be taken in making keyways and shear grooves.
raised key is required, the form shall be filled to overflowing and a platform vibratox used to compact the concrete and bond the key to the body
of the lift.
22 IS : 457 - 1957
Form vibrators shall be permitted-only for special purpose
specified under 22.214.171.124
and extreme care shall be exercised to avoid
pumping air into the concrete.
4.11.5 Surface Voids - Large voids or air pockets, which may be left
in the permanently exposed faces of the structure by vibration, shall be
spading the face in the following manner.
motor-driven, slowly revolving, square steel rod
shall be held in a vertical position and moved slowly back and forth in
short intervals along the entire face. Care shall be taken to avoid prolonging such spading to the point of leaving excess mortar in the face.
4.12 Depositing Concrete Under Water 4.12.1 Concrete shall not be deposited under water, if it is practicable
to unwater the area and place the concrete in the regular manner.
it is found necessary to deposit any concrete under water, the method,
equipment, materials and mix shall first be approved by the engineer-incharge. Concrete shall not be placed in runni...
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This document was uploaded on 10/01/2013.
- Fall '13