Title: Supplementary Data on the Effect of Concrete Aggregate Having Low Thermal Coefficient of Expansion
Author(s): J. C. Pearson
Publication: Journal Proceedings
Appears on pages(s): 33-40
This is a continuation of the study reported in A Concrete Failure Attributed to Aggregate of Low Thermal Coefficient, V. 38, p. 29. A limited num-ber of tests were made on 2 x 2 x IO-in. bars con- taining two types of low coefficient aggregates and one type of silica pebbles, which were submitted to cycles of temperature changes from -20 F to room temperature. After about 50 cycles, bars containing the low coefficient aggregates lost 40 to 50 percent of their original modulus of elasticity whereas the bars containing silica pebbles lost only 2 or 3 percent of their original modulus. Expansions during these cycles were not large but that of the low coefficient aggregate bars was 3 or 4 times that of the silica pebble bars. After 100 cycles of temperature changes, the bars were submitted to freezing and thawing cycles of the same temperature range as before. The bars containing the low coefficient aggregates succumbed rapidly to the frost action while the silica bars were only moderately affected by the same treatment. The results lend further support to the conclusion of the earlier paper by the author, namely, that low thermal coefficient aggregates can be a source of danger in concrete exposed in cold climates.