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Please use this identifier to cite or link to this item: http://ntour.ntou.edu.tw:8080/ir/handle/987654321/12088

Title: 鋼筋混凝土在陰極防蝕電流作用下之行為研究(II)
A Study on the Properties of Reinforced Concrete Under the Cathodic Protection Current (II)
Authors: 張建智
Contributors: NTOU:Department of Harbor and River Engineering
國立臺灣海洋大學:河海工程學系
Keywords: 陰極防蝕電流;鹼骨材反應;電流密度;水灰比;硬度試驗
cathodic current;alkali-silica aggregate reaction;current density;water/cement ratio;microhardness test
Date: 2003-08
Issue Date: 2011-06-29T01:38:06Z
Publisher: 行政院國家科學委員會
Abstract: 摘要:本 研 究 係 針 對 在 陰 極 防 蝕 電 流 作 用 時,是否造成加速鹼骨材反應之影響進行 研究。研究方法是利用高鹼性水泥及易產 生鹼骨材反應之骨材製成模擬具鹼骨材反 應試體後,經 由外加 陰極電流所造 成之 鈉、鉀離子往鋼筋界面處集中,因而對鋼 筋界面處鹼骨材反應造成加速的效果。研 究中係以水灰比、初始鹼含量及外加電流 密度為試驗變 數,利 用裂縫初始生 成時 間、裂縫寬度成長觀察、硬度及鋼筋抗拉 試驗等來探討陰極防蝕對具鹼骨材反應試 體所造成的影響,最後透過鈉、鉀離子滴 定,以瞭解加速鹼骨材反應的原因。 經由研究結果顯示初始裂縫生成時間 會隨著初始鹼含量增加、電流密度增大及 水灰比提高而有縮短的現象,同時裂縫寬 度成長亦有相同之趨勢。此外,從硬度試 驗及鈉、鉀離子累積含量可瞭解通電後, 鋼筋混凝土界面有加速鹼骨材反應的現 象。最後,由鋼筋抗拉試驗結果發現隨著 影響參數ψ( ic×tp 為鋼筋單位面積之總電 量)的增加,將對降伏強度、極限強度及 伸長率造成一定程度的折減,尤以伸長率 折減最為明顯,此意謂著陰極電流將造成 鋼筋脆化的效應。本研究之成果,未來或 可提供陰極防蝕施作上之一參考警訊。
abstract:In this study, whether or not the cathodic current will accelerate the alkali-silica aggregate reaction is investigated. It is expected that sodium and potassium ions will be attracted to the rebar-concrete interface due to the cathodic current such that the alkali-silica aggregate reaction will be initiated and accelerated. Using NaOH solution to adjust the initial alkali content and pyrex glass, the specimens having high potential of alkali-silica aggregate reaction were made. Variables considered were w/c ratio, initial alkali contents and cathodic current density. Crack initiation time, crack mouth opening history, microhardness and tensile strength of rebar were adopted to investigate the effects of cathodic current. In addition, chemical titration to determine amount of accumulated sodium and potassium ions was performed to s upport our viewpoints. Results showed that the crack initiation time shortened as increasing the initial alkali content, w/c ratio and/or cathodic current density. Crack opening rate also increased in the same manner. In addition, microhardness test indicated that rebar-concrete interface significantly softened when potassium and sodium ions increased. It was found as the influence parameter, phi (defined as the product of cathodic current density and polarization time, i.e., ic x tp), increased the yield strength, the ultimate strength and elongation percentage all decreased. The decrement in elongation percentage was most apparent. This result indicated that hydrogen embrittlement of rebar existed. Our research pointed out that application of thecathodic current required careful consideration.
Relation: NSC92-2211-E019-023
URI: http://ntour.ntou.edu.tw/ir/handle/987654321/12088
Appears in Collections:[河海工程學系] 研究計畫

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