CORRELATION BETWEEN STRENGTH OF SMALL AND STANDARD CONCRETE CYLINDERS

Presents an analysis of the influence of specimen size on the measured compressive strengths of plain and fly ash concretes exposed to stand ard and cold-curing. Strength tests were performed on three classes of air-entrained concrete using two subbituminous fly ashes at three rep lacement levels. Analysis of the present experimental results, combine d with other results presented in the literature, shows that the compr essive strength indicated by 75-mm (is-approximately-equal-to 3-in.) c ylinders is statistically identical to that indicated by 150-mm (is-ap proximately-equal-to 6-in.) cylinders. Analysis suggests that this one -to-one relationship between strength of 75- and 150-mm cylinders may be valid for concrete strengths up to 50 MPa (7250 psi). Further analy sis of published data leads to the conclusion that the equality of str ength among specimen sizes also includes 100-mm diameter cylinders. Th e type of mold used to cast test cylinders, whether cardboard, steel, or tin, does not have a significant effect on the trends observed.