Impact Products CN652 User Manual download pdf (Page 9)

4.4.2 Select Curve

The compressive strength of the concrete fck can be calculated from the rebound

value R by means of conversion curves. There are 3 options available for

calculating the compressive strength of the concrete:

- No conversion

- Select 5 internal conversion curves, or

- Choose between 2 programmed PROCEQ standard curves (fck 7 days and fck

14 to 56 days).

No Conversion

Select ”No Conversion”.

At the end of a measurement series, only the average of the rebound values 

in relation to the impact direction is displayed.

The corresponding compressive strengths of the concrete can be taken from the

conversion curves in Fig. 8.1 and Fig. 8.2 under ”Standard Conversion Curves”.

Internal Conversion Curves

Parameters a, b and c of the curve functions must first be set in the sub-menu

”Set up curve”.

• Under line number 1 to 5, select the conversion curve.

Select PROCEQ Standard Curves

For the derivation of the PROCEQ Standard curves, refer to ”Derivation of the

PROCEQ Standard Conversion Curves”.

• Select conversion curve A in line no. 7 for concrete with an age of 7 days (fck7)

or the conversion curve in line no. 28 for concrete with an age of 14 - 56 days

(fck28).

4.4.3 Set up Curve

The curve no. (1 to 5) and the parameters a, b and c (see under ”Creating New

Conversion Curve”) can be set using the arrow keys.

4.5 Corrections

4.5.1 Shape Coefficient 〈s

The PROCEQ standard curves fck7 and fck28 are valid for sample cubes with a

200 mm side for EPROM versions up to 1.3 or from a 150 mm side from EPROM

version 2.0. If test specimens with different dimensions are used for determining

the compressive strength in the pressure testing machine, the shape coefficient

in the first line is to be set or selected in line 2 to 4.

Shape of the test specimen:

1. Line: ”variable”, see Table 4.1

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Impact Products CN652 User Manual Page 9