While it is reasonable to expect that immersion of specimens in heated water would result in weight gain, the opposite occurred. Two of the samples had marked weight loss during the course of the test period, presumably because volatile materials were emitted from the specimens as a part of a prolonged curing process.

Specimens of all three materials responded to the test cycle by typically gaining weight when im­mersed in water and losing weight when dried. There is, however, a significant difference in the amplitude of changes in different samples.

Specimens of all three materials lost dimension during the course of a test cycle. The amount of loss paralleled the loss of weight in the specimens.

We did not find a significant difference between the performance of specimens conditioned in a laboratory versus those conditioned in variable cool conditions. Both sets of samples had the same envi­ronment during the first three days of curing, which may be a critical period.

Recommendations for Standards Improvement