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1 – 3 of 3Bo Da, Hongfa Yu, Haiyan Ma and Zhangyu Wu
This paper aims to reduce the cost, limit the time and increase raw material source availability, coral aggregate seawater concrete (CASC) composed of coral, coral sand, seawater…
Abstract
Purpose
This paper aims to reduce the cost, limit the time and increase raw material source availability, coral aggregate seawater concrete (CASC) composed of coral, coral sand, seawater and cement can be widely used for the construction of ports, levees, airports and roads to achieve practical engineering values. However, the naturally porous coral structure and abundant Cl− in the seawater and coral lead to extremely severe reinforcement corrosion for CASC. It is well known that Cl− is the main cause of reinforcement corrosion in the marine environment. Therefore, it is necessary to research the reinforcement corrosion of CASC in the marine environment.
Design/methodology/approach
In this study, linear polarization resistance was adopted to test the linear polarization curves of reinforcement in CASC with different exposure times. Ecorr, Rp, Icorr and Vcorr were calculated according to the weak electrochemical polarization theory and Stern–Geary formula. The effects of concrete cover thickness, exposure time, reinforcement types and inhibitor on reinforcement corrosion in CASC were analysed. The reinforcement corrosion degradation rule was determined, which provided theoretical support for the durability improvement, security assessment, service life prediction and service quality control of CASC structures in marine islands and reef engineering.
Findings
The corrosion resistance was enhanced with increased concrete cover thickness, and the concrete cover thickness for organic new coated steel should be at least 5.5 cm to reduce the reinforcement corrosion risks in CASC structures. The corrosion resistance of different types of reinforcements followed the rule: 2205 duplex stainless steel > 316 stainless steel > organic new coated steel > zinc-chromium coated steel > common steel. In the early exposure stage, the anti-corrosion effectiveness of the calcium nitrate inhibitor (CN) was superior to that for the amino alcohol inhibitor (AA). With the extension of exposure time, the decreasing rate of anticorrosion effectiveness of CN was higher than that of AA.
Originality/value
Reinforcement corrosion of CASC in a marine environment was studied. Concrete cover thickness, exposure time, reinforcement type and inhibitor influenced the reinforcement corrosion were investigated. New technique of reinforcement anti-corrosion in marine engineering was proposed. Possible applications of CASC in marine engineering structures were suggested.
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Zhangyu Wu, Hongfa Yu, Haiyan Ma, Bo Da and Yongshan Tan
Coral aggregate seawater concrete (CASC) is a new type of lightweight aggregate concrete that is becoming widely used in reef engineering. To investigate the corrosion behavior of…
Abstract
Purpose
Coral aggregate seawater concrete (CASC) is a new type of lightweight aggregate concrete that is becoming widely used in reef engineering. To investigate the corrosion behavior of different kinds of rebar in CASC exposed to simulated seawater for 0-270 d, the electrochemical techniques, including linear polarization resistance (LPR) technique and the electrochemical impedance spectroscopy (EIS), were used in the present work.
Design/methodology/approach
The electrochemical techniques, including LPR technique and the EIS, were used in the present work.
Findings
Based on the time-varying law of linear polarization curves, self-corrosion potential (Ecorr), polarization resistance (Rp), corrosion current density (Icorr), corrosion rate (i), and the characteristics of EIS diagrams for different types of rebar in CASC, it can be found that the anti-corrosion property of them can be ranked as epoxy resin coated steel > 2205 duplex stainless steel (2205S) > 316 L stainless steel (316 L) > organic coated steel > ordinary steel. Additionally, the linear regression equation between Rp and charge transfer resistance (Rct) was established. Finally, the EIS corrosion standard of rebar was established from the LPR corrosion standard, which provides a direct standard for the EIS technique to determine the condition of rebar in CASC.
Originality/value
The linear regression equation between polarization resistance and charge transfer resistance was established. And the EIS corrosion standard of rebar was established from the LPR corrosion standard, which provides a direct standard for the EIS technique to determine the condition of rebar in CASC.
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Keywords
Anand S. Arya, G.S. Mandal and E.V. Muley
To provide a review of the general aspects of tsunamis and the specific aspects of the 2004 tsunami impacts on the coastal areas of India and surrounding islands.
Abstract
Purpose
To provide a review of the general aspects of tsunamis and the specific aspects of the 2004 tsunami impacts on the coastal areas of India and surrounding islands.
Design/methodology/approach
The approach is a general discussion of the 2004 tsunami and its effects in areas in South East Asia, followed by the specific impacts in the Andaman and Nicobar Islands, including the damage to water supply and power systems, and a situation analysis of the communities, land and housing.
Findings
The impact of the 2004 tsunami highlights the vulnerability of the coastal areas and islands of India. The multi‐hazard situation existing on the sea coast of the mainland as well as in the islands of Andaman and Nicobar require a holistic multi‐hazard mitigation approach as a long term measure. The recovery programs presently in hand are being planned taking the multi‐hazard situation in view, so as to provide protection from such hazards in future.
Originality/value
Provides a review of the effects of the 2004 tsunami in the coastal areas and islands near India.
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