VARIABILITY OF SOILS CLASSIFICATION TESTS

As part of a developing program of assessment of soils laboratory testing, interlaboratory studies have been conducted to determine the scatter of results obtained by testing officers of the Road Construction Authority, Victoria in several soils classification tests; namely, particle size distribution (-4.75 mm), liquid limit, plastic limit, plasticity index and linear shrinkage tests. The results of these studies were distributed to participants in the form of Youden diagrams. Statistical procedures were used to determine whether operators had inconsistent results, whether results were influenced by laboratory or operator effects, whether any operator or laboratory had unusual bias in results and to estimate components of scatter. Estimates of the repeatability and reproducibility are given. The scatters of results obtained are compared to those reported in other studies and are concluded to be similar. Using the observed testing scatter an evaluation is also made of what is effectively being specified in the Road Construction Authority in terms of grading and plasticity for crushed rock products. The number of the covering abstract for the conference is TRIS No. 393385. (Author/TRRL)