Quality Assurance Handbook for Rural Roads Volume-I - pmgsy

3. Section-900
2. Lower centering gradually and uniformly so as to permit the concrete to take self weight, uniformly
and gradually to avoid shock or vibration. At reentrant angles of concrete sections, remove
formwork soon after setting of concrete to prevent shrinkage cracking.
3. When internal metal ties are permitted, remove them or their parts without damaging concrete.
Fill the holes left out with cement mortar (1:3)
4. The time of removal of formwork when OPC is used without any admixtures is given in Table
900.1 Otherwise it may be taken as 14 days for Superstructure.
A 4 Reuse of Formwork
TABLE 900.1: TIME FOR REMOVAL OF FORMWORK
1. After dismantling examine individual components for damage and remove damaged pieces for
rectification.
2. Straighten all bent steel propos before reuse, the maximum deviation from straightness being 1/
600 th of its length. Reduce permissible axle loads on props by a minimum of 10 percent after each
reuse, depending on their condition.
B. Quality Control Requirements
1 Tolerances in Formwork
Member No. of days
Walls, piers, abutments, columns and vertical faces 0.5 to 2
of structural members
Soffit of slab (with prop left under) 3
Props (left under slabs) 14
Soffit of girders (with props left under) 7
Props (left under girders) 21
(a) Deviations form the specified dimensions of cross + 12 mm
section of columns, beams - 6 mm
(b) Deviations dimensions of footing/open foundation
(i) Dimensions in plan + 50 mm
(ii) Eccentricity in plan 0.02 times the width - 12 mm
of the footings in the direction of deviation
but not more than 50 mm
(iii) Thickness ± 0.05 times the
specified thickness
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