MASS CONCRETE TESTS IN LARGE CYLINDERS,
 31^st Annual Convention, American Concrete Institute, New York, by R.F. Blanks and C.C. McNamara, February 1935, 22 pages.

THE PROGRAM of mass concrete research conducted by the Bureau, of Reclamation in the Denver laboratories in connection with the design and construction of Boulder dam included tests in cylinders varying in size from 2 x 4 to 36 x 72 in. to determine the effect of various factors, on compressive strength, Young's Modulus and Poissoii's Ratio. The concretes used in these tests included mixes in which the maximum size of aggregate varied from 1/4 to 9 in. and from full mass concrete with 9-in. aggregate to wet-screened concrete having 1/8-in. maximum particles.

The data obtained from the Boulder dam investigations have evaluated, for concretes with Arizona aggregates, the following variable factors in terms of indicated compressive strength, elastic properties and physical characteristics:

1. Size of test cylinder

2. Maximum size of aggregate

3. Wet-screening

In addition, the relationship between full mass concrete tested in large cylinders and wet-screened concrete tested in small cylinders, as is customary in field control tests, has been established, together with a comparison between standard (fog) and mass curing for various placing temperatures.