Geokon 4370, Instruction Manual, Page: 14 / 19

6. DATA REDUCTION
6.1 Stress Calculation
To convert digits to concrete stress, use the linear or polynomial equation from the calibration
report provided with the stressmeter. See Appendix C for a sample calibration report
The linear equation is as follows:
Concrete Stress (S) = (R
1
– R
0
) × G
Equation 1 - Digits to Concrete Stress (Linear Equation)
Where;
R
1
is the current reading.
R
0
is the initial reading, usually obtained at installation just before the concrete is poured.
(NOTE: For greater accuracy use the regression zero found on the calibration report as R
0
.)
G is the linear gauge factor, in MPa/digit or psi/digit taken from the calibration report.
The cross-sectional area of the Stressmeter is equal to 5.31 sq in.
For example:
If;
Initial field zero reading = 7035 digits
Regression zero = 7071
R
1
= 5219 digits
G = -0.01748 MPa/digit
Then;
The calculated concrete stress using Equation 1 and the
initial field zero =
S = (5219 – 7035 ) x -0.01748 = 31.74 MPa
The calculated concrete stress using Equation 1 and the
regression zero =
S = (5219 − 7071 ) × -0.01748 = 32.37 MPa