Effect of length-to-diameter ratio of core sample on concrete core strength - Another look

Abstract

Cores with diameters of 144,94,69, and 46 mm and length-to-diameter(1/d) ratios of 0.75,1,1.25,1.5,1.75, and 2, were removed from beam specimens produced from eight different concrete mixtures. Compressive strength tests were conducted on a total of 1876 core specimens. Strength correction factors were determined for converting the strength of the cores with 1/d ratios ranging from 1.75 to 0.75 to the strength of an equivalent standard specimen with a 1/d ratio of 2. The effects of type and maximum size of aggregate and core diameter on these correction factors were examined. As it was expected, the correction factors gradually decreased with the decrease in 1/d. The effect was found to be more pronounced for cores with a smaller diameter. The results also revealed that the effects of type and maximum size of the aggregate on correction factors were not significant. The proposed strength correction factors differ only slightly from those currently recommended in ASTM C 42/C 42M-04 [1] and they are very close to those proposed by Bartlett and MacGregor cited by Arioglu et al. [2-4].