The purpose of this installation was to compare the durability of concrete containing 6-in. maximum size aggregate to that of concrete containing 3-in. maximum size aggregate. In December 1963, 18 mass concrete prisms were installed at half-tide elevation. After 2278 cycles of freezing and thawing, all prisms had failed. The prisms were made from 18 different concrete mixtures; the coarse and fine aggregate used in all mixtures was a crushed limestone. Each concrete mixture was air entrained (5 ± 1 percent) with a slump of 2 ± ½ in., and each contained Type II portland cement.

Cement factors were 2.0, 2.5, or 3.0 bag per cu yd; 12 mixtures also contained a cement-replacement material. The maximum size of aggregate in all mixtures was either 3 or 6 in. Table 1- CAP of TR 6-553 lists these specimens and gives their exposure record along with other pertinent information. The results obtained after 13 winters of exposure indicate the following:
a. The prisms with a cement factor of 3.0 bag per cu yd are more durable than those with a cement factor of 2.5 bag per cu yd, and these (2.5-bag prisms) are more durable than those with a cement factor of 2.0 bag per cu yd.
b. A conclusive difference in durability between prisms made with 6-in. maximum size aggregate and those made with 3-in. maximum size aggregate is not evident although those with 3-in. maximum seemed to do slightly better.