140
0
¼
½
¾
-¼
1
12
3
4
5
6
7
80
160
40/40
34/40
12/16
18/25
26/40
[inch]
[inch]
Accuracy
D
r
: Real Diameter
D
s
: Set Diameter
D
r
/D
s
Real Cover
[mm]
4 mm
[mm]
Fig 25: Accuracy of cover measurements and overlapping rebars
Table 1 and Figure 25: Accuracy for cover measurements when setting the measured diameter
• For smaller rebars with a diameter up to 16 mm / # 5 the accuracy of cover measurement is
within 1 mm to 4 mm / 0.04” to 0.16”
• For rebars with a diameter from about 18 mm to 30 mm / # 6 to # 9 the accuracy of cover
measurement is within 0 to 3 mm / 0.00” to 0.12”
NOTE! Without setting the measured diameter the error can be up to 44 mm / 1.73”
• For larger rebars with a diameter > 30 mm / > # 9 the accuracy of cover measurement is within
1% to 15% of the actual cover.
The accuracy is decreasing with larger cover.
Special case of measuring cover at stirrups
You will find typical arrangement of rebars with stirrups in concrete beams, columns, piles and girders.
For some common arrangements you may refer to the Excel-Macro “Cover Measurement at Stir-
rups” on our website www.proceq.com under Profoscope.
NOTE! In all other cases the first layer rebar must be exposed on some spots to deter-
mine the real cover and compare it with the Profoscope readings.
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