President, John A. Bickley Associates Ltd., Toronto, Ontario
Assistant professor, University of Toronto, Toronto, Ontario
Senior engineer, Construction Technology Laboratories, Skokie, IL
Project coordinator, PCL Constructors, Inc., Nepean, Ontario
Although both ASTM and CSA have had standards for testing the compressive strength of concrete cylinders since the 1920s, neither standard contains a statement of the within- and between-laboratory precision of its test method as prescribed by Practice for use of the Terms Precision and Bias in ASTM Test Methods (ASTM E 177). This paper describes an interlaboratory study performed by 16 CSA-certified Ontario testing laboratories in accordance with Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method (ASTM E 691). The analysis shows that the variability of the test results increases with the mean strength of the concrete. A precision statement based on the results reported here is recommended for inclusion in Test Method for Compressive Strength of Cylindrical Concrete Specimens (ASTM C 39) and CSA A23.2-9C (Compressive Strength of Cylindrical Concrete Specimens).
Paper ID: CCA10330J