Bruce Suprenant, Technical Director, The Voice Newsletter June 2018

The concrete industry relies heavily on the results of concrete compressive strength tests to determine specification compliance or to allow construction activities such as form removal or post-tensioning to take place. While testing the strength of concrete is a simple test and controlled by an ASTM standard, the measured results are very much dependent upon adhering strictly to the ASTM procedures. Violation of these procedures can lead to inaccurate results.

Fortunately, Richardson (“Review of Variables That Influence Measured Concrete Compressive Strength”, ASCE Journal of Materials Engineering, May 1991) was able to quantify the effect of nonstandard cylinder testing on the measured strength and summarized it into a Table. The background for this Table information can be found in Richardson’s paper and can be purchased for $30. Next time a measured cylinder strength is reported low, consider if one of more of these variables might have reduced that strength.