Technical Questions

ACI Committees, Membership, and Staff have answered common questions on a variety of concrete related topics.

Using cube tests in lieu of cylinder tests

Q. Can ASTM C109 cube tests be used in lieu of ASTM C39 cylinder tests?


A. Mortar cube tests (ASTM C109) could be a good indicator of potential strength, but they should not be the sole basis for evaluating concrete strength. To meet ACI 318 requirements, concrete tests should be run on trial batches of concrete made with proposed aggregates, supplementary cementitious materials (SCMs), and chemical admixtures. Note that this requirement is specifically important for evaluating high strength concrete according to ACI 363R-10 “Report on High-Strength Concrete”.

If you wanted to make and test concrete cubes, as is done in several European countries, and then use the cube test results to determine if the ACI 318 requirements for specified compressive strength of concrete have been met, it would be necessary to take into account the effect of specimen geometry on test results. The lower aspect (height-width) ratio for standard 6 × 6 in. (150 × 150 mm) cubes results in a higher apparent strength than would be obtained using 6 × 12 in. (150 × 300 mm) cylinders.


References: ACI 318-19; ACI 363R-10; ASTM C39; ASTM C109

Topics in Concrete: 318 Building Code; High Performance Concrete; Quality Assurance; Testing of Concrete

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