Specification Part 3 - Road & Bridge Works - Urban Administration ...

1701. DESCRIPTION
The work shall consist of furnishing and placing structural concrete and incidental construction in
accordance with these specifications and in conformity with the lines, grades and dimensions, as
shown on the drawings or as directed by the Engineer in charge.
1702. MATERIALS
All materials shall conform to Section 1000 of these Specifications.
1703. GRADES OF CONCRETE
1703.1. The grades of concrete shall be designated by the characteristic strength as given in
Table 1700-1, where the characteristic strength is defined as the strength of concrete below
which not more than 5 per cent of the test results are expected to fall.
TABLE 700-1.
Grade Designation Specified characteristic Compressive strength of 150 mm
cubes at 28 days, in MPa
M 15 15
M 20 20
M 25 25
M 30 30
M 35 35
M 40 40
M 45 45
M 50 50
M 55 55
1703.2 The lowest grades of concrete in bridges and corresponding minimum cement contents
and water-cement ratios shall be maintained as indicated in Tables 1700-2 and 1700-3.
TABLE 1700-2
FOR BRIDGES WITH PRESTRESSED CONCRETE OR THOSE WITH INDIVIDUAL SPAN
LENGTHS MORE THAN 30 M OR THOSE THAT ARE BUILT WITH INNOVATIVE
DESIGN/CONSTRUCTION
(A) MINIMUM CEMENT CONTENT AND MAXIMUM WATER CEMENT RATIO
Structural Mia cements content for all
Max. Water cement ratio
Member exposure conditions
Exposure Condition
(kg/cu.m)
Normal
Severe
1 PCC
member
2 RCC
member
3. PSC
members
360 0.45 0.45
400 0.45 0.40
400 0.40 0.40
(B) MINIMUM STRENGTH OF CONCRETE
Member
Normal
Conditions of Exposure
Severe
1 PCC member M 25 M 30
2 RCC members M 35 M 40
3 PSC members M 35 M 40