Volume 28, Issue 2 (March 2000)
Precision of ASTM D 5821 Standard Test Method for Determining the Percentage of Fractured Particles in Coarse Aggregate
An interlaboratory study was conducted to develop a precision statement for ASTM D 5821-95, Standard Test Method for Determining the Percentage of Fractured Particles in Coarse Aggregate. The experimental design included ten laboratories, four materials, and three replicates per material per laboratory, resulting in 54 degrees of freedom. Outlier detection was given careful con sideration due to the subjective nature of the method, and resulted in exclusion of one laboratory's data, reducing the degrees of freedom to 48. The materials included three partially crushed gravel blends and one quarry stone blend.
As expected, multilaboratory variability was greater than singleoperator variability. There was also a greater level of variability associated with two or more fractured face determinations than with one or more fractured face determinations. Surprisingly, the greatest variability was observed for the quarry stone rather than for the crushed gravels. The results of the analysis were compared with other available data. The level of variability associated with this study was less than that observed in other studies, due most likely to the highly fractured nature of the materials used in the study.