 The purpose of this installation was to develop data on the effect of specimen size on the durability of concrete specimens in the tidal exposure of Treat Island. In December 1968, 18 concrete specimens (of four different sizes) were installed at half-tide elevation. |
The installation consisted of
12 beams (three were 6- by 6- by 30-in. and nine were 3½- by 4½- by 16-in.),
three 2-ft cubes (8 cu ft), and three prisms (18- by 18- by 36-in.). The
specimens were made from six batches of the same concrete mixture. The
mixture contained Type II portland cement, crushed limestone fine and
coarse aggregates, and had the following characteristics: a. Air content, 4½ ± ½ percent. b. Cement factor, 6.0 ± 0.3 bag per cu yd. c. Water-cement ratio, 5.5 gal per bag. d. Slump, 2½- ± ½ in. e. Nominal 28-day compressive strength, 5,000 psi. The attached table lists the specimens and gives their exposure record along with other pertinent information. After 22 winters of exposure, the small beams (3½- by 4½- by 16-in.) failed, one 6- by 6- by 30-in. beam failed. All cubes and prisms are still intact. |