Nordic evaluation of methods for testing fresh self-compacting concrete (NT TR 558)

Abstract

  In this study a modified inter-comparison test was proposed for evaluating the precision of methods for testing fresh SCC whose properties are not identical from laboratory to laboratory or even from batch to batch. The modification includes collecting a number of sets of similar equipment and carrying out a local inter-comparison test in each laboratory by different operators, each operating a number of sets of equipment. In this way each laboratory produces local within-operator and between-operator deviations, from which the pooled repeatability and reproducibility deviations can be estimated using the modified statistic model. The modified inter-comparison test has been tried in the Nordic countries with five participating laboratories. The results show again that it is hardly possible to produce fresh SCC with identical properties in different laboratories. The proposed modification to the conventional inter-comparison test can to great extent get rid of the effect of different properties of fresh concrete from different laboratories or batches so that more proper evaluation of the precision of test methods for fresh SCC could be reached.