particular specifications (road works) - CIDCO Maharashtra Ltd.

CIDCO OF MAHARASHTRA LTD
C.A.No.01/CIDCO/SE(KHR)/EE(KHR-I)/2010–11 Pg. No. 353
5.7.1.6 Before commencing the works the contractor shall submit the Engineer
for approval full details of all preliminary trial mixes and tests.
5.7.1.7 When the proportions of a concrete mix have been approved by the
Engineer the contractor shall not vary the quality or source of the
materials or the mix without the written approval of the Engineer.
5.7.2 The cement content W.C. ratio and maximum size of aggregate for
different grades of concrete and the required average strengths at 28
days for which the mixes shall be designed are specified below:-
Grade of
concrete
Characteristic
strength
(f’ ck Mpa)
TABLE-1
Min.
cement
Content
kg/m 3
Max
W/C
Remarks
M-20 20 310 0.45 For PCC bedding
M-20 20 310 0.40
M-30 30 400 0.40
For PCC bridge
work
For RCC bridge
work
M-35 35 400 0.40 For all RCC work
Note: 1) If the contractor is unable to obtain the required concrete strength, with
the given minimum dosage of cement, he can with specific approval of
Engineer, increase the cement dosage. In such cases, no extra
payments will be made for the use of extra cement.
2) Use of approved super plasticizer, at contractor’s cost is mandatory.
Table – 2 given below, shown, the range of slump for concreting in
various areas and conditions.