profometer PM8000 Quick Reference page 18

Measurement – Rebar Diameter
Factors Affecting Diameter Determination
Two factors affect the determination of the rebar diameter:
1. Cover depth.
Diameter can be determined for rebars with cover not exceeding 80% of
the Standard range. 64 mm / 2.5".
2. Spacing between neighboring bars.
For accurate determination of the diameter, the spacing between the
rebars must be greater than the limits shown in the drawing below with
reference to the MC (4).
Diameter Measurement on Areas with sufficient Spacing of the
Rebars
Method 1
Map out a rebar grid on a test surface and then select one rebar from the grid that has
sufficient spacing from other rebars. Step 1 Create a rebar grid as described in 5.2.4. Step 2
Select one rebar that has the largest spacing from neighboring rebars. Step 3 Use a ruler
and confirm that the spacing is at least as indicated in 3.4.4. If not, redo Steps 1 and 2 until
a rebar is located with the required spacing to a neighboring rebar. Step 4 Place the MC (4)
of the PM8000 over the rebar at the midpoint line of the rebars running crosswise to the
rebar under test and click the Function Key (6) on the left side.
CL(9)
Midpoint line
MC(4)
Diameter Measurement on Areas with insufficient
Spacing of the Rebars (Neighboring Rebar Correction)
Method 2
Neighboring rebars that are within the sphere of influence will be detected by the
PM8000 and will affect cover depth and diameter estimation results. A insufficient
spacing is smaller as the minimum spacing defined in 3.4.4. The effects of
neighboring rebars can be mitigated by keying-in a correction value. NOTE! This
works only for rebars of the same layer running in parallel to the rebar under test.
Step 1 Create a rebar as described in 5.2.4. Step 2 Select one rebar that has the
largest spacing from neighboring rebars. Step 3 Use a ruler to measure the
spacing. In case the spacing from the rebar under test to a neighboring rebar is
equal or less than 130 mm / 5.2" go to the main menu, select the icon and input
the measured spacing. Verify that neighboring rebar correction symbol is active in
the status line at the top of the display. Step 4 Place the MC (4) of the PM8000
over the rebar at the midpoint line of the rebars running crosswise to the rebar
under test and click the Function Key (6) on the left side.