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A23.4-09
©
Canadian Standards Association
November 2009
Table 1
Cover to reinforcement, tendon sheaths, and ducts*
3EE
#LAUSE
%XPOSURE
.OT
EXPOSEDp
%ARTH OR
WEATHER
#HLORIDES SULPHATES MANURE SEWAGE AND INDUSTRIAL EFFLUENTS
5NPROTECTED CONCRETE
0ROTECTION SYSTEMSo
!
" # $ %
& ' (
* +
Exposure condition
(see Table 2 of
CSA A23.1)
N
F-1, F-2 C-1, C-3,
A-1, A-2,
A-3, S-1,
S-2, S-3
C-XL
C-1, C-3,
A-1, A-2,
A-3, S-1,
S-2, S-3
C-1, C-3,
A-1, A-2,
A-3, S-1,
S-2, S-3
C-1, C-3,
A-1, A-2,
A-3, S-1,
S-2, S-3
Piles
— 40 mm 50 mm 40 mm —
40 mm 40 mm
Beams, girders, and
columns
20 mm 30 mm 50 mm 40 mm —
40 mm 30 mm
Slabs, walls, joists,
shells, and folded
plates
20 mm 25 mm 50 mm 40 mm 40 mm 40 mm 35 mm
Ratio of cover to
nominal bar
diameter§
1
1.5
1.5
(cover
d
60)
1.5
(cover
d
60)
1.5
(cover
d
60)
1.5
(cover
d
60)
1.5
(cover
d
60)
Ratio of cover to
nominal maximum
aggregate size
1.0**
1.5
1.5
(cover
d
60)
1.5
(cover
d
60)
1.5
(cover
d
60)
1.5
(cover
d
60)
1.5
(cover
d
60)
Cover to mesh
reinforcing in all
precast products
20 mm 25 mm 40 mm 35 mm 30 mm 35 mm 30 mm
*
The cover for precast concrete is reduced from the cover used in cast-in-place concrete because of greater dimensional
control of formed concrete, tighter tolerances on placement of reinforcing, and better quality of concrete in plant-controlled
conditions.
†
A = membrane
†
B = concrete with a rapid chloride permeability test result (ASTM C1202) of less than
1000 coulombs
within
56 d
and
black reinforcing within
100 mm
of the exposed surface
†
C = corrosion inhibitor and black reinforcing within
100 mm
of the exposed surface
†
D = sealer and black reinforcing within
100 mm
of the exposed surface
†
E = corrosion inhibitor and black reinforcing within
100 mm
of the exposed surface
†
F = sealer and galvanized reinforcing within
100 mm
of the exposed surface
†
G = concrete with a rapid chloride permeability test result (ASTM C1202) of less than
1000 coulombs
within
56 d
and
galvanized reinforcing within
100 mm
of the exposed surface
†
H = corrosion inhibitor and galvanized reinforcing within
100 mm
of the exposed surface
†
J = sealer and corrosion inhibitor
†
K = stainless steel reinforcing within
100 mm
of the exposed surface
‡
Refers only to concrete that will be continually dry within a conditioned space (i.e., members entirely within the vapour
barrier of a building envelope).
§
The cover for a bundle of bars shall be determined from a circle circumscribing the perimeter of the bundle.
**
The specified cover from screeded surfaces shall be at least 1.5 times the nominal maximum aggregate size to reduce
interference between aggregate and reinforcement where variations in bar placement can result in a cover smaller than
specified.
Note:
Greater cover or protective coatings can be necessary where there is exposure to industrial chemicals, food
processing chemicals, and other corrosive materials. See CSA A23.1 and PCA IS001.
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