The influence of autocorrelation on OC-lines of compliance criteria for concrete strength

Abstract

For the calculation of Operating Chacteristic (OC) lines of compliance criteria, it is necessary to introduce a model that reflects the stochastic nature of the relevant variable as realistically as possible. As far as concrete is concerned, it was found that a significant autocorrelation exists between consecutive strength values. As shown in the paper, this aspect has important consequences for the resulting probabilities of acceptance as its effect may be represented as a reduction of the effective number of observations. In order to stimulate the consideration of autocorrelation by people concerned with compliance control of concrete, both exact and approximate methods that take into account autocorrelation are presented and the practical application is illustrated. © 1987 RILEM.