Evaluation of the Modified Slab Test for Resistance of Concrete to Internal Frost Damage.

摘要

This report presents the results from the precision evaluation of the modified slab test for resistance of concrete to internal frost damage. Two round Robin tests, one at the Nordic level and another at the RILEM level, were carried out in the project. Three non-destructive detecting techniques, Ultrasonic Pulse Transmission Time (UPTT), Dilation (length change) and Fundamental Frequency (FF), were evaluated through the round Robin tests. A destructive method (flexural strength test) was employed to examine the deterioration of concrete in mechanical properties due to internal frost damage. The results show that all the three techniques can be employed in the slab test for detecting internal damage of concrete subjected to frost attack. The dilation method reveals a better repeatability, but has a reproducibility similar to the UPTT technique. The temperature effect on test precision seems not significant. Therefore, the same frost test procedure as described in the Swedish standard SS 72 13 44 can be used in the modified slab test. Due to a very small number of laboratories participated in the FF test the precision estimate for this technique involves a large uncertainty. Since the FF test reveals promising sensitivity to detecting internal damage, further collaboration study is needed for evaluating the precision of this technique.