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| Research on Influence Testing Ages on Pore Structure of Concrete |
| XU Hua-xuan |
| China Railway 16th Bureau Group Corporation, Beijing 100018, China |
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Abstract Research purposes：In the existing concrete frost resistance test, the rapid freeze-thaw test is often adopted, with long test cycle and high cost. On consideration to that the pore structure could stably exist in hardened concrete, the research was done on determining the relation between test age and concrete pore to reduce the test cycle of frost resistance.
Research conclusions：The hardened air content of C30 concrete increases gradually with the increase of age, while there are not obvious rules between pore structure and age ofC50 concrete. The air-entraining ggent of poor quality will introduce the large amount of large-diameter bubbles to decrease the compressive strength of concrete. As the C50 Concrete is of much viscosity, the more AEA is needed, generating smaller bubbles than C30 Concrete. The test sample preparation is an important step in the process of bubble structure test. The strength of the sample will affect the measured results. To ensure accurate test results, the test age of C30 concrete is not be earlier than 28 days, while the steam curing of C50 concrete is notbe earlier than 7days. In the premise of ensuring the frost resistance of concrete, the bubble spacing coefficient of different concrete is quite different, and the bubble spacing coefficient of C30 concrete is larger than C50 concrete.
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Received: 14 April 2010
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2010, Vol. 27 
