Interpretation of Concrete Strength for Nonstandard Specimens

A total of about 210 cylinders and cubes of five different sizes and aspect ratios made from eleven batches of concrete were tested in direct compression to establish the interrelationships between their strengths. The range of concrete strengths considered was between 20 and 100 MPa. All specimens prepared from each batch of concrete were cured under identical conditions before testing at the same age. An analysis of these data together with those generated earlier at the National University of Singapore has revealed that the ratio of standard cube strength to that of other specimens decreases with an increase in the level of concrete strength. Also, a decrease in either the size or the aspect ratio of specimens leads to a decrease in this ratio. Expressions relating the compressive strengths of cylinders of two different sizes and two different aspect ratios, and of smaller size cubes with standard cube strength, are presented. These expressions may be combined to obtain useful interrelationships between the strengths of any two types of specimens.