PACKAGE : I Bid Document VOLUME : II - Public Health Engineering
PACKAGE : I Bid Document VOLUME : II - Public Health Engineering
PACKAGE : I Bid Document VOLUME : II - Public Health Engineering
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Dropping of concrete from an excessive height or running or working it along forms<br />
will not be permitted. Any concrete which, before placement has begun to set and<br />
has become stiff shall be rejected.<br />
Concrete shall not be disturbed after it has been placed in the form and has begun to<br />
set. Concrete shall be carefully placed in horizontal layers which shall be kept at an<br />
even height throughout the work. Concrete shall not be allowed to slide or flow<br />
down sloping surfaces directly into its final position but shall be placed in its final<br />
position form the skips, trucks, barrows, down pipes or other placing machines or<br />
device or, if this is impossible it shall be shoveled into position, care being taken to<br />
avoid separation of the constituent materials. Concrete placed in horizontal slabs<br />
from barrows or other tipping vehicles shall be tipped into the face of the previously<br />
placed concrete.<br />
Concrete dropped into place in the work shall be dropped vertically. It shall not<br />
strike the formwork between the point of its discharge and its final place in the<br />
work and except by approval of the Engineer, it shall not be dropped freely through<br />
a height greater than 1.5 metres. Chutes & Conveyor belts shall be so designed that<br />
there is no segregation or loss of mortar and shall be provided with a vertical<br />
tapered down pipe or other device to ensure that concrete is discharged vertically<br />
into place.<br />
Where a lift of concrete is built up in layers each layer shall be properly merged into<br />
the proceeding layer before initial set takes place.<br />
7.4 Quality assurance.<br />
General procedure:<br />
General: In order to achieve the required strength and associated properties of<br />
concrete, proper control of the Water/Cement ratio by weight need be enforced.<br />
The strength shall be prime consideration and W.C. ratio as prescribed by Engineer<br />
in charge shall have to be observed.<br />
Operators: At no time whatsoever will the mixer operator or those supervising or<br />
inspecting the works be permitted to alter the quantity of water specified by the<br />
Engineer for mixing the concrete. Batching shall be accurate and as specified by<br />
the Engineer.<br />
GTS : General Technical Specification. Page 53
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