Refence of the current Vietnamese standards for concrete cover thickness.
Post date: 10-11-2016
Concrete cover thickness of steel rebar can be determined by calculating of cracking limit state and crack width under the impact of external forces. In case of no calculation, we can refer the following standards:
A/ Regarding Reinforced concrete structures in normal conditions:
Standard TCXDVN 356 : 2005 CONCRETE AND REINFORCED CONCRETE STRUCTURES – DESIGN STANDARD
I/ Regarding the axial reinforcing steel bar (non pre-stressed, pre-stressed), the concrete cover thickness are not smaller the diameter of steel bar or strand and not smaller than:
II/ Regarding stirrups, distribution and constructive reinforcement, the concrete cover thickness are not smaller than diameters of these steel bars and not smaller than:
- if the height of structure smaller than 250 mm: ......10mm (15 mm)
- if the height of structure equal or greater than 250 mm:.15 mm (20 mm)
III/ Concrete cover thickness of at the end of pre-stressed structures along the length of stress transmission must be not smaller than:
- with steel bar class CIV, A-IV, A-IIIB:.... 2d
- with steel bar class A-V, A-VI, AT-VII:.... 3d
- with steel strand:..................................... 2d
(where d is nominal diameter of steel bar, in milimeter)
In addition, the thickness of concrete cover mentioned-above must be not smaller than 40mm for all kind of steel rebar and not smaller than 30mm for steel strand.
B/ Regarding Reinforced concrete structures of Hydraulic works
I. Standard TCVN 4116:1985 HYDRAULIC CONCRETE AND REINFORCED CONCRETE STRUCTURES- DESIGN STANDARD
a/ Concrete cover thickness of the reinforced concrete structures in hydraulic works:
b/ Concrete cover thickness of the reinforced concrete structures in hydaulic works at sea must not smaller than:
70mm – with load bearing wire steel rebar in bundle.
50mm - with load bearing steel rebar;
30mm – with distribution rebar and stirrups;
c/ With precast reinforced concrete structures that concrete strength equal or greater 200 kg/cm2, concrete cover thickness can be reduced 10mm in comparision with the values mentioned-above.
d/ In case that reinforced concrete structures are placed in aggressive environment, the concrete cover thickness must be specified according to the particular standards.
II. Standard TCVN 9139:2012 HYDRAULIC WORK- CONCRETE/REINFORCED CONCRETE STRUCTURES IN LITTORAL AREA- TECHNICAL REQUIREMENTS
Table 1 – Technical requirements in design of the concrete and reinforced concrete structures of hydraulic work in the saline areas
Table 2 – Technical requirements in design of the concrete and reinforced concrete structures of hydraulic work in the acidic alum areas
C/ Regarding Reinforced concrete structures in marine environment:
Standard TCVN 9346:2012 CONCRETE AND REINFORCED CONCRETE STRUCTURES- REQUIREMENTS OF CORROSION RESISTANCE IN MARINE ENVIRONMENT