• 콘크리트학회지
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• 제11권2호
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• pp.231-239
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• 1999

바다에 콘크리트를 타설 할 때는 육상과는 달리 여러 가지 제약을 받게 되며 타설 후에는 해양의 물리, 화학작용과 혹독한 기상작용을 받게 된다. 해양환경에서 내구적인 고품질의 콘크리트를 제조하기 위해 플라이애쉬를 혼입한 수중 불분리 콘크리트를 해수 중에 타설${\cdot}$양생한 후 압축강도를 측정하고 기중 및 담수 중에서 양생한 것과 비교하여 그 특성을 구명하였다. 우리 나라 연안의 87년에서 96년까지 10년간 수심 10m에서 20m의 연 평균수온이 14.9$^{\circ}C$ 임을 고려하여, 수온을 $15{\pm}3^{\circ}C$로 조절할 해수 중에 타설${\cdot}$양생한 후 콘크리트의 압축강도를 측정하여 플라이애쉬 사용효과를 확인하였다. 시험결과 해수 중에서 플라이애쉬를 사용하지 않은 불분리 콘크리트의 경우 재령 91일부터 1년까지의 강도증가는 2%에 머무나 플라이애쉬를 단위 결합재 중량비로 10%에서 50%까지 10%씩 증가시켜 치환한 결과 압축강도는 각각 15%, 19%, 24%, 51%, 64%가 증가되었다. 플라이애쉬의 적정 사용량은 콘크리트의 조기강도가 요구되는 구조물의 경우 단위 결합재에 대한 중량비로 10%정도 치환함이 적절하며, 내구성과 경제성을 고려한다면 40%~50%정도가 효과적임을 알 수 있었다.

• 대한기계학회논문집A
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• 제27권3호
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• pp.363-371
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• 2003

This study is mainly concerned with phenomenon of cavitation-erosion on the several materials and corrosive liquids which were applied with vibrator(suggested by ASTM G 32, 20KHz, 50$mu extrm{m}$). The maximum erosion rate by cavitation erosion in both of distilled water and sea water appeared to be proportioned to their hardness and tensile strength. Cavitation weight loss and rate of cast iron in sea water condition were greater(approximately 3 times) than that in distilled water condition, however in case of stainless steel and brass the cavitation weight loss of composite materials were not so different in both of their conditions. Cavitation weight loss of composite materials were shown as below on this test, Duratough DL : Weight loss in sea-water condition were greater (approximately 2.3 times) than it's distilled water condition. The main tendency of cavitation erosion for metals appeared that small damaged holes causing by cavitation erosion was observed with radial pattern. On the other hand, the tendency for composites appeared that small damaged holes were observed randomly.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 1999년도 추계학술발표대회 논문집
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• pp.227-233
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• 1999

This study is mainly concerned with phenomenon of cavitation-erosion on the several materials and corrosive liquids which were applied with vibrator (suggested by ASTM G-32, 20KHZ, 24{$mu}m$).The main results obtained are summarized as follows ; (1) The maximum erosion rate by cavitation erosion in both of fresh-water and sea-water appeared to be proportioned to their hardness and tensile strength. (2) Cavitation weight loss and rate of cast iron in sea-water condition were greater (approximately 3 times) than that in distilled-water condition, however in case of stainless and brass the cavitation weight loss and their rates were not so different in both of their conditions. (3) Cavitation weight loss of composite materials were shown as below on this test, DuraTough DL : Weight loss in sea-water condition were greater (approximately 2.3 times) than it's fresh-water condition. (4) As the result of observation with digital camea of specimens, the main tendency of cavitation erosion for metals, was that small damaged holes causing by cavitation e개sion was appeared with radial pattern, and composites materials was that small damaged holes were appeared randomly.