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Title |
The Effect of Entrained Air Contents on the Properties of Freeze-thaw Deterioration and Chloride Migration in Marine Concrete
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Keywords |
염화물 확산 ; 연행공기 ; 동결융해 ; 해양콘크리트 ; 모의부재 Chloride migration ; Entrained air ; Freeze-thaw ; Marine concrete ; Mock-up specimens |
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Abstract |
The freeze-thaw deterioration and chloride attack, which are the typical degradation factors for durability of marine concrete, are significantly affected by pore structures in terms of penetration and diffusion. These pore structures of concrete are closely related to the types and amount of AE agent, used to guarantee the resistance of freeze-thaw deterioration, and the elapsed time before concrete pouring. This paper evaluates the durability of concrete based on the results of tests on cylinder specimens and core specimens from mock-up members with different air content of 4～6% and 8～10%, respectively. According to the test results, the air content of hardened concrete is 2.5～5.2% at 7 days and 2.4～5.1% at 28 days. These air contents are about half of the initial values just after the concrete mixing. Judging from the amount of scale after the freeze-thaw test completed, air content of 8～10% is slightly more beneficial against the deterioration of concrete than air content of 4～6%. Meanwhile, the core specimens from mock-up members exhibit somewhat unfavorable freeze-thaw deterioration and chloride migration characteristic compared with the cylinder specimens tested in the laboratory under the same mixing condition, as to show 106% in freeze-thaw test and 160% in chloride diffusion coefficient test, respectively.
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