| Summary: | 碩士 === 國立成功大學 === 土木工程學系碩博士班 === 93 === It requires many years to estimate the durability of concrete structures; however, constructors cannot wait for such a long time – this research is aimed to adopt methods of acceleration by speeding up destruction to obtain long-term results of durability in a short term. In this study, there were two kinds of concrete, NWC (Normal Weight Concrete) and LAC (Light-weight Aggregate Concrete), and three curing periods, separately 7, 14 and 28 days. The experiment was carried out on cylinders. The accelerated terms were as follows:
1. Solutions were water and saturated sodium sulfate.
2. Temperatures of solutions were 20 and .
3. Dry-Wet cyclic times were twenty-one for NWC and fourteen for LAC.
Dry-Wet cyclic method was according to ASTM C88, that is, immersed for 16~18 hours and dried for 4~6 hours.
In each cycle, we measured the mass and length changes, strength changes with UST and impacted hammer, micro structure changes with SEM, and steel corrosion voltage with M.C.M. Finally, three same specimens in each type of concrete were immersed in saturated sodium sulfate solution to evaluate the reappearance of accelerated method.
The test results are as follows:
1. Dry-Wet cycle had the best accelerated result, but solution and temperature had no accelerated effort.
2. The Coefficient Variation of mass changed only between +3 to –7%. It proved a nice reappearance in this accelerated method.
3. Low water/cement could lower probability of steel corrosion, but water/cement and probability of steel corrosion were not direct proportion.
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