EN 206:2014: Cusum method or mean value criterion?

Figure: Schmidt, Kühne

Shewhart control chart system with warning lines at 2σ and control lines at 3σ

Figure: Schmidt, Kühne

Cusum control chart for the record shown in Fig. 1

Figure: Schmidt, Kühne

Process evaluation using a cusum curve and V-masks

Figure: Schmidt, Kühne

Standard V-mask and V-mask according to EN 206:2014

Figure: Schmidt, Kühne

Examples of various conformity analyses using Methods B and C

Figure: Schmidt, Kühne

Location of a hypothetical cusum curve that exactly meets the mean value criterion within the warning and control lines according to Annex H

Figure: Schmidt, Kühne

Examples of random normally distributed cusums with production mean values of
f_cm= f_ck +1.96σ,
f_cm= f_ck +1.64σ and
f_cm= f_ck +1.48σ for a cal‑
culated target value of
f_cta= f_ck +1.96σ

Figure: Schmidt, Kühne

Figure: Private

The recently adopted EN 206:2014 standard includes the option of using cusum control charts to evaluate the conformity of the production process at the precast plant. Are these charts a valid alternative to the mean value criterion? Is their use perhaps even associated with true benefits?

Since July 2014, the EN 206:2014 standard has been in force to specify the requirements for concrete for buildings and engineering structures; it superseded EN 206:1:2000. This standard provides the option of using so-called control charts to verify conformity. In EN 206:2014, the application of the mean value criterion is referred to as Method B, whereas the use of control charts is termed Method C. Control charts based on cumulative sums (cusums) are very effective tools for production control purposes. Their use is governed by BS ISO 7870-4:2011.

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