Concrete production - an application of OC curves in conformity control

The decision on conformity or non-compliance of strength is made on the basis of a comparison of the results of testing of the mean value and minimum value of the compressive strength of concrete with the compliance criterion. This decision is made on the basis of the adopted statistical quality control plan. The quality monitoring of concrete has to be carried out throughout its production process. There are various techniques for the monitoring of quality concrete, namely Control charts: Cusum, Schewart and EWMA Control charts or operational-characteristic (OC) curve and average outgoing quality curve. In the case of concrete quality control, it may be an OC curve of a random sampling plan according to a numerical value or alternative evaluation, or an OC curve of the operational rule for testing concrete strength. The paper presents an analysis and assessment of the risk associated with making the second type of error related to compressive strength of concrete. For analysis, the OC curve of the operational rule for testing concrete strength, with OC curve of the second type of error was used as a function of the actual average compressive strength of the concrete.