1. Rationale
Revise 10.3 Loading Rate The rate of loading for compression testing of concrete masonry units and related units is set in ASTM C1314. For constructed prisms, this rate allows for the technician to apply the first half of the expected load at any convenient rate, and then to apply the second half of the load at a rate such that the test specimen fails within 1 to 2 minutes. For field removed prisms, the first of the load is applied at any convenient rate, while the remained should be applied in 2 to 4 minutes. While determining this rate is not exact, it has been shown to provide relatively uniform loading without shocking the specimen by loading too fast or loading the specimen to slow. The task group was made aware by CCRL that some laboratories are requiring an extra specimen be tested to determine the expected load, which increases the number of specimens needed for strength from 3 to 4 and likely increasing the cost of testing. While this practice is acceptable, the task group felt this additional test is unnecessary, and that the laboratories can use judgment when determining the rate, even if this means the first of three specimens is slightly out of the allowed range. This ballot proposes relaxing the time requirements for the first specimen to be tested. It is also noted that a similar change was proposed and approved in ASTM C140, Standard Test Methods for Sampling and Testing Concrete Masonry Units.
Keywords
compressive strength of masonry (fmt); masonry prism; masonry prism strength; masonry specimen; specified compressive strength of masonry (f ′m); Capping prisms; Compliance testing; Compression testing--masonry/mortar; Constructing masonry prisms; Grouted prisms; Masonry prisms; Prism construction; Prisms ;
Citing ASTM Standards
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