Technical Specifications - UNDP

of walls 25
Bars in top of ground slabs 20
Bars near faces in contact with soil 40
The placing of all reinforcement will be checked by the Engineer and in no case is concrete to be
poured around any steel that has not been passed by him. The Contractor is to ensure that no steel
is displaced from its position during the placement of concrete and until the concrete is set.
The insertion of bars into or removal of bars from concrete already placed will not be permitted.
Reinforcement temporarily left projecting from the concrete at the joints shall not be bent without
the prior approval of the Engineer.
Secondary reinforced concrete members for which no reinforcement details are given in the
drawings or the Particular Specifications shall have a minimum ratio of reinforcement area to
concrete area of 0.33 % .
4 Concreting
Cement
The cement used shall be Portland Cement conforming in all respects to ASTM Standard
Specification C150 , type 1 , or to BS 12 , unless otherwise required , bags shall contain
50kg net + 1% .
If cements other than the above are required they shall be covered fully by the Particular
Specification.
The Contractor shall at all times furnish the Manufacturer's statement of the above Standard
Specifications together with the date of manufacture, certified by an independent agency in the
country of origin approved by the Engineer .
The cement shall be delivered to the site by the Contractor in the original sealed and branded bags
or containers of the manufacturer in batches not exceeding 100 tons and shall be stored in a proper
manner off the ground to prevent deterioration . Each batch shall be stacked separately and used in
the order of delivery. No cement shall be used which has been manufactured more than twelve
months prior to its proposed use on site .
All cements whether stored in bulk, bags, or containers in warehouses or on site shall be sampled
for testing according to ASTM C183 (Methods of Sampling Hydraulic Cements). Test samples
over and above those specified shall be taken at any time if so requested by the Engineer. Testing
of cement shall be in accordance with the methods required by ASTM C150 and C175 or BS 12 or
any other accepted by the Engineer .
Aggregates
This specification covers fine and coarse aggregates other than lightweight aggregates for use in
the production of concrete.
When lightweight aggregates are required they shall be defined in the Particular Specification.
The aggregates shall be crushed gravel or stone and shall comply with BS 882 for graded or
single size aggregate and shall be obtained from any quarry in the mountains approved by the
Engineer . For convenience part of Clause 5 of BS 882 (grading) including Tables 1 , 2 and 3 are
reproduced herein .
14