Several Factors Regarding Sustainability of Marine Concrete Structures

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Title: Several Factors Regarding Sustainability of Marine Concrete Structures

Author(s): T. U. Mohammed, H. Hamada, and N. Otsuki

Publication: Special Publication

Volume: 212

Issue:

Appears on pages(s): 23-44

Keywords: blended cement; chemical admixtures; corrosion; joints; steel bars; steel-concrete interface; sustainability; type of bars

Date: 6/1/2003

Abstract:
Several factors regarding sustainability of marine concrete structures are dis- cussed based on detailed laboratory and several long-term exposure tests. The factors include voids at the steel-concrete intarface, crack widths and autogeneous healing, blended cements, chemical admixtures, type of bars, and joints. Long-term exposure investigations were carried out utilizing the specimens exposed to the marine environment over 10 years. The following conclusions are drawn: 1. To enhance long-term durability, the steel-concrete interface should be free from voids; 2. Narrower cracks and joint surfaces are healed in the marine tidal environment with alkaline deposits, and thereby control the corrosion of steel bars at these locations; 3. Blended cement with high slag content shows the best performance for long- term durability compared to the normal ponland cement and other investi- gated blended cements; 4. The napthalene group of chemical admixture shows the best performance for long-term durability compared to other investigated chemical admixtures; 5. Deformed bars are more prone to corrosion compared t oplain bars; 6. Brushing-off the laitance and application of a mortar coat at the joint plane is very effective in enhancing long-term durability.