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Title: 鋼筋混凝土在陰極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
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
Issue Date: 2011-10-20T08:11:20Z
Publisher: 行政院國家科學委員會專題研究計畫成果報告
Abstract: 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。
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/handle/987654321/24318
Appears in Collections:[河海工程學系] 期刊論文

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