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Full-Text Articles in Engineering
Corrosion Of Rebar Under Carbonation And Salt Environment, Wei-Chung Yeih, Jiang-Jhy Chang, Yu-Ping Huang, Ran Huang
Corrosion Of Rebar Under Carbonation And Salt Environment, Wei-Chung Yeih, Jiang-Jhy Chang, Yu-Ping Huang, Ran Huang
Journal of Marine Science and Technology
In this study, the behavior of reinforced concrete under carbonation and in a salt environment was investigated. Three types of cements- Type I cement, Type II cement and highalumina cement (HAC) - were used to study the influence of cement on reinforced concrete behavior. To simulate chloridecontaminated concrete, 1% NaCl (by cement weight) was added to some groups of specimens. Results revealed that the carbonation released chloride ions from Friedel's salt, which increased the chloride content near the carbonation front. The carbonation rate of HAC concrete was higher than that of Type I and Type II cement concrete. The corrosion …
Reversing Sensitization Of Naturally Exfoliated 5456-H116 Aluminum Alloys, Ren-Yu Chen, Cheng-Chyuan Lai
Reversing Sensitization Of Naturally Exfoliated 5456-H116 Aluminum Alloys, Ren-Yu Chen, Cheng-Chyuan Lai
Journal of Marine Science and Technology
5456-H116 Al-Mg alloy has been broadly used in the U.S. Navy in order to meet the demand of reducing ship hull weight while considering high specific strength, corrosion resistance, and weldability. A particular concern of these alloy is sensitization, which causes it to be sensitized when highly anodic β phase (Al3Mg2) is precipitated at grain boundaries especially in service exceeding 65~200°C, leading to intergranular corrosion (IGC), exfoliation and stress corrosion cracking (SCC). This study investigated the reversal of sensitization of a naturally exfoliated 5456-H116 alloy plate by planned heating treatment with a short exposure to 250°C. The properties of sensitized …
A Real Case Study On The State Of Corrosion Of The Spanish Boats, José A Orosa, Juan José Galán, Mar Toledano
A Real Case Study On The State Of Corrosion Of The Spanish Boats, José A Orosa, Juan José Galán, Mar Toledano
Journal of Marine Science and Technology
In this real case study we analyze various corrosion problems encountered in Spanish fleets and present possible solutions. As a first step, we developed a statistical analysis of the north Mediterranean Sea fleets to define the age of the vessels, hull construction material and main activities involved. As a result, different corrosion problems were identified as well as solutions like paint, sacrificial anodes and impressed currents, and of course, improved design. Generally, we can state that, according to the results obtained, a series of incidents have increased the repair and maintenance costs of the vessels in the area under study
Rust-Expansion-Crack Service Life Prediction Of Existing Reinforced Concrete Bridge/Viaduct Using Time-Dependent Reliability Analysis, Ming-Te Liang, Jiang-Jhy Chang, Han-Tung Chang, Chi-Jang Yeh
Rust-Expansion-Crack Service Life Prediction Of Existing Reinforced Concrete Bridge/Viaduct Using Time-Dependent Reliability Analysis, Ming-Te Liang, Jiang-Jhy Chang, Han-Tung Chang, Chi-Jang Yeh
Journal of Marine Science and Technology
It is necessary to develop a calculation method to help in the making of feasible, reliable, and serviceable predictions for the service lives of bridge or viaduct structures. This article presents the basis for doing rust-expansion-crack service life predictions for existing reinforced concrete (RC) bridges and viaducts in chloride-laden environments based on timedependant reliability modeling due to the corrosion of steel in concrete. The corrosion process has three stages, the initiation (diffusion or carbonation) time (ti = tc), the depassivation time (tp), and the propagation (corrosion) time (tcorr). The rustexpansion-crack service lives (tcr) of existing RC bridges or viaducts can …
Safety Stock Estimation Of Unit Load Devices For International Airline Operations, Hua-An Lu, Chien-Yi Chen
Safety Stock Estimation Of Unit Load Devices For International Airline Operations, Hua-An Lu, Chien-Yi Chen
Journal of Marine Science and Technology
Unit load devices (ULDs) are used to load air cargo and passengers’ checked baggage for wide-bodied aircraft operations. Since ULDs are reusable at the destination, airlines can invest in an appropriate fleet size for their requirements. The estimation of safety stock levels for every operating airport is a premeditated task because airlines must prepare enough devices for the outbound consignments of each flight. The variance of the number of used devices for each arrival and departure flight will influence the stock level of an airport. For scheduled international services, this study proposes an analytic method based on a cyclically time-sequenced …
Service Life Prediction Of Pier For The Existing Reinforced Concete Bridges In Chloride-Laden Environment, Ming-Te Liang, Ran Huang, Shen-An Feng, Chi-Jang Yeh
Service Life Prediction Of Pier For The Existing Reinforced Concete Bridges In Chloride-Laden Environment, Ming-Te Liang, Ran Huang, Shen-An Feng, Chi-Jang Yeh
Journal of Marine Science and Technology
The prediction method of service life for bridge structures is played an important role of bridge management system. In this paper, the mathematical modeling was to study the servise life prediction of pier for existing reinforced concrete (RC) bridge exposed to chloride environment. The corrosion process has three stages, the initiation time (tc), the depassivation time (tp), and the corrosion (propagation) time (tcorr). The total service life of pier for the existing RC bridge can be expressed as t = tc + tp + tcorr. Many mathematical models were applied to predicting each value of the tc, tp, and tcorr. …
Mathematical Modeling And Prediction Method Of Concrete Carbonation And Its Applications, Ming Te Liang, Wenjun Qu, Chih-Hsin Liang
Mathematical Modeling And Prediction Method Of Concrete Carbonation And Its Applications, Ming Te Liang, Wenjun Qu, Chih-Hsin Liang
Journal of Marine Science and Technology
The carbonation process of concrete is principally a diffusion phenomenon. The penetration rate of carbon dioxide depends mainly on the concrete quality and the exposure condition. Based on both Fick’s first and second laws of linear diffusion equations, the threedimensional equation of conservation of mass is expressed. This equation can be reduced to two- and one- dimensional equations of conservation of mass which can predict the carbonation depth beneath corners and the general surface of concrete structures, respectively. The objectives of this investigation are to measure the depth of carbonation from the free surface of a concrete member and to …
Protection Of Steel Using Aluminum Sacrificial Anodes In Artificial Seawater, Tai-Ming Tsai
Protection Of Steel Using Aluminum Sacrificial Anodes In Artificial Seawater, Tai-Ming Tsai
Journal of Marine Science and Technology
The performance of aluminum alloys used as sacrificial anodes for cathodic protection in seawater was investigated in this study, Results show that A1 -3.5%Zn -0.05%In sacrificial anode alloy C has the best current efficiency, most negative open circuit potential and energy characteristics among five different Al-Zn-In alloys. Polarization curve of alloy C also shows no passivation behavior in artificial seawater. The corrosion rate of mild steel in artificial seawater was determined as a function of applied cathodic potential. The cathodic protection potential determined for mild steel in seawater was -0.78 V,SCE for a corrosion rate of less than 1 mpy. …
Pitting Of Fe-Mn-Al Alloys In Nacl Solution, M Ruscak, T.P Perng
Pitting Of Fe-Mn-Al Alloys In Nacl Solution, M Ruscak, T.P Perng
Journal of Marine Science and Technology
the increase of ferrite content. However, the nearly ferritic alloy showed much better passivation behavior, presumably due to the addition of 6% Cr.In aerated solution, no or very small passive region was observed. From the immersion test, the general corrosion was found to be minor. Pitting corrosion was the primary corrosion except for the ferritic alloy. The pits were found more frequently in the ferrite phase or at the interface between the ferrite and austenite phases.