Title: Are 4 x 8 Inch Concrete Cylinders as Good as 6 x 12 Inch Cylinders for Quality Control of Concrete?

Author(s): V. M. Malhotra

Publication: Journal Proceedings

Volume: 73

Issue: 1

Appears on pages(s): 33-36

Keywords: compressive strength;concretes;cylinders;density (mass/volume);quality control;research;specimens.

DOI: 10.14359/11053

Date: 1/1/1976

Abstract:
This paper reports data which have become available at the CANMET over the past several years as to the relative merits of 4 x 8 in. (102 x 203 mm) and 6 x 12 in. (152 x 305 mm) cylinders for quality control of concrete. The types of concrete investigated incorporated limestone and gravel as the coarse aggregates and natural sand as the fine aggregate. The nominal water-cement ratio varied from 0.33 to 0.87. Each set of test specimens consisted of two 4 x 8 in. (102 x 203 mm) and two 6 x 12 in. (152 x 305 mm) cylinders, cured under standard moist room conditions and tested at ages ranging from 3 days to about 8 months. The analyses of the data indicate: (a) That the compressive strengths of 4 x 8 in. (102 x 203 mm) cylinders are higher than those of 6 x 12 in. (152 x 305 mm) cylinders. There are, however indications that at low strength levels, the reverse may be true. (b) That the difference in the strength of two sizes of cylinders increases with an increase in the strength level of concrete. (c) That the standard deviation of the compressive strength of test cylinders increases with decrease in the cylinder diameter as indicated by Tucker’s "summation-strength" theory. However, the magnitude of this increase is such that considerably more than twice the number of 4 x 8 in. (I 02 x 203 mm) cylinders will have to be tested for each 6 x I2 in. (52 x 305 mm) cylinder to obtain the same degree of precision.