Technical-Resources-for-Concrete-Contractors
Technical-Resources-for-Concrete-Contractors
Technical-Resources-for-Concrete-Contractors
Technical-Resources-for-Concrete-Contractors
Technical-Resources-for-Concrete-Contractors
Technical-Resources-for-Concrete-Contractors

Referee Test for Flexural Strength Acceptance

ASCC Position Statement #16

Specifications from the Federal Aviation Administration (FAA), some highway departments, city and county engineers, and consulting engineers include requirements for flexural strength based on beam tests. Because results of beam tests are extremely variable, many highway departments and consulting engineers use only compressive strength requirements in their specifications, or allow in-place flexural strength to be estimated based on concrete cylinder compressive strength tests.

Specifications that require beam testing often contain no provisions for referee testing. This is unusual in the concrete industry because for many years ACI 318, “Building Code Requirements for Structural Concrete,” and ACI 301, “Specifications for Structural Concrete,” have included core testing as the referee method when cylinder strength test results are low.

When project specifications include requirements for flexural strength based on beam testing, the specifications should also provide guidance for investigation of low beam strength test results. The investigation should include a review of the testing procedures, a consideration of whether the low-strength beam represents a significant reduction in load-carrying capacity of the pavement or slab, and the effect on overall load-carrying capacity of slab thicknesses and k-values that exceed the design requirements. A referee method of testing, such as compressive strength tests of drilled cores, should also be stated. A commonly stated specification clause is that core test results must meet the requirements of ACI 318 or ACI 301 for structural adequacy.

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