ASTM C512/C512M-15 PDF Download

The ASTM C512/C512M-15 standard provides a procedure for measuring the load-induced time-dependent compressive strain of concrete under controlled environmental conditions. This test method is used to compare the creep potentials of different concretes and can also be used to calculate stress from strain data in non-reinforced concrete structures. However, for specific design applications, the test conditions outlined in the standard may need to be modified to better simulate the anticipated curing, thermal, exposure, and loading age conditions of the actual structure.

The standard assumes that creep is proportional to stress up to 40% of the concrete's compressive strength. It also emphasizes that creep is directly proportional to the paste content of the concrete mixture, especially in mixtures with aggregate larger than 50mm (2 inches) in size. In such cases, the creep characteristics can be determined from the sieve sample of the minus 50-mm fraction, and adjusted based on the ratio of the cement paste content between the full mixture and the sieved sample.

Although the use of a logarithmic expression is mentioned in Section 9 of the standard, it does not imply that the creep strain-time relationship is necessarily an exact logarithmic function. Instead, the logarithmic expression is used to approximate normal creep behavior over the course of one year, allowing for the calculation of parameters that facilitate comparisons between different concretes.

It is important to note that the results of this test method are limited to compression and cannot be extrapolated to tension or torsion. The standard indicates that there are no data to support such extrapolation.