Title: Volume Changes in Small Concrete Cylinders During Freezing and Thawing
Author(s): Rudolph C. Valore
Publication: Journal Proceedings
Appears on pages(s): 417-434
Keywords: no keywords
The volume-temperature behavior of small concrete cylinders was observed, using a new mercury-displacement dilatometer, during freezing and thawing cycles in which the range 40 to -20 F was traversed at various rates. Specimens cast from a mix containing 6 bags of portland cement per cu yd, plain and modified by the addition of an air-entraining agent, were tested in air-dry, vacumn-saturated and partially saturated conditions. Volume-temperature relationships for sir-dry specimens yielded uniform thermal expansion data, but those for vacumn-saturated specimens showed departures in the form of transient expansions during freezing, and residual expansions for following thawing of about 0.8 and 0.4 percent, respectively; a single slow cycle produced decreases in dynamic E exceeding 60 percent. Much smaller departures were observed for partially saturated specimens (65 to 85 percent of vacumn-saturation) and included, in addition to transient and residual expansions, secondary effects of freezing termed "shrinkage" and relaxation phenomena. The magnitude of the transient and residual expansions appeared to depend upon the rate of cooling and heating, the degree of saturation of the specimen and, during the slow cycle, upon the degree of supercooling before freezing.