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Please use this identifier to cite or link to this item: http://ntour.ntou.edu.tw:8080/ir/handle/987654321/13504

Title: 使用爐石及熱浸鍍鋅鋼筋對混凝土梁抗蝕及力學行為影響之研究
Corrosion Resistance and Mechanical Properties of Reinforced Concrete Beams using GGBS and Hot-dipped Zinc Coated Reinforcing Steel
Authors: An Cheng
鄭安
Contributors: NTOU:Institute of Materials Engineering
國立臺灣海洋大學:材料工程研究所
Keywords: 爐石;熱浸鍍鋅;腐蝕
GGBS;Hot-dipped Zinc Coated;Corrosion
Date: 2004
Issue Date: 2011-06-30T07:22:22Z
Abstract: 中文摘要 本研究旨在利用材料試驗及構件試驗探討使用爐石及熱浸鍍鋅鋼筋對RC梁腐蝕及力學行為之影響。材料試驗包括爐石混凝土及熱浸鍍鋅鋼筋試驗;主要試驗項目有熱浸鍍鋅鍍層分析,爐石混凝土壓汞孔隙試驗、SEM微觀觀察、快速氯離子滲透試驗、透水試驗、電阻係數試驗、壓力試驗、初始吸水速率及吸水率試驗,同時利用動態極化法評估鍍鋅鋼材暴露於不同pH溶液中的腐蝕速率。RC梁試體變數包括混凝土配比、預載及持續載重條件、使用熱浸鍍鋅鋼筋等。主要試驗項目有加速腐蝕試驗、開路電位、極化電阻量測、及中點載重試驗等。 材料試驗結果顯示熱浸溫度468℃,熱浸時間2min,鍍鋅層由外層至內層可分為純鋅層、zeta ( )、delta ( )及基材四層,鍍鋅層平均厚度約為87□m。鍍鋅鋼筋在pH9~pH12水溶液中腐蝕電位低於普通鋼筋;鍍鋅鋼材暴露於含氯離子溶液中,腐蝕電位趨向活性,腐蝕速率大幅度成長。爐石依重量替代40%水泥之混凝土,漿體總孔隙體積無明顯變化,但大於10nm的毛細孔隙體積明顯減少;而使用60%爐石之混凝土,其總孔隙率及大毛細孔隙率皆降低。爐石取代水泥量越高時,齡期91天試體壓力強度越高,氯離子快速穿透試驗獲致的6小時總電荷通過量越低,透水係數亦愈低。 梁試驗結果顯示爐石混凝土梁與普通混凝土梁比較,極限載重較高,持續加速腐蝕21天後,鋼筋腐蝕電流密度較低。預載愈大(0.75Pu)且持續加載,會使混凝土中的裂縫擴大並持續存在,導致暴露於3.5% NaCl水溶液中的混凝土梁迅速腐蝕並大幅降低其載重能力。鋼筋未發生腐蝕前,鍍鋅鋼筋混凝土梁的極限載重約為普通鋼筋鋼筋混凝土梁的107~110%。加速腐蝕試驗結果顯示鍍鋅鋼筋混凝土梁暴露於含有3.5%NaCl水溶液中,較普通鋼筋混凝土梁的腐蝕情況更為嚴重且混凝土梁的極限載重大幅折減。同時,相較於普通鋼筋混凝土梁,高持續預載對於鍍鋅鋼筋混凝土梁腐蝕速率及極限載重的影響更為明顯。
Abstract The objective of this study is to evaluate the corrosion and mechanical properties of reinforced concrete beams using GGBS and hot-dip zinc coated rebar. Concrete mixes consisted of 40% and 60% GGBS replacements for cement and one water/binder ratio of 0.55 was selected. Material tests include mercury intrusion porosimetry (MIP) analysis, rapid chloride penetration test (RCPT), permeability test, initial surface absorption test (ISAT), resistivity, absorption test, compressive strength test, and SEM observation. And, potentiodynamic polarization method was applied to evaluate the corrosion current of steel specimens in various pH solutions. RC beam was produced with one of three concrete mixes and embedded with rebar or hot-dip zinc coated rebar. RC was subjected to preloading (0.37Pu, 0.75Pu) or sustained loading (0.37Pu, 0.75Pu) before accelerated corrosion test. Test results indicate that specimens with partial replacement of cement by ggbs have lower 6-hour total charge-pass and permeability coefficient. Total intrusion volume of mercury and capillary pore porosity decrease with an increase in slag addition. Slag addition and preloading type have significant effect on the corrosion rate and flexural rigidity of RC beams. Test results from potentiodynamic polarization curves show that zinc has higher corrosion rate and more negative corrosion potential in alkaline solution with chloride ion. The ultimate load for RC beam with zinc-coated rebar is higher than that with uncoated rebar. After accelerating corrosion process, GGBS in concrete seems no significant negative effect on corrosion behavior of zinc-coated rebar. The loading history has more prominent effect on rebar corrosion due to the crack initiation. As corrosion rate of rebar increases, the remaining loading capacity of the beam and the effective moment of inertia of cross section decrease. Exposed to 3.5%NaCl solution for a short time, RC beam with zinc-coated rebar was subjected to serious corrosion and lost its loading capacity much more than RC beam with uncoated rebar. When electrochemical method was used to measure the corrosion behavior of zinc-coated rebar, open circuit potential may not properly reflect the corrosion condition and the corrosion current density should be used instead.
URI: http://ethesys.lib.ntou.edu.tw/cdrfb3/record/#G0D88550003
http://ntour.ntou.edu.tw/ir/handle/987654321/13504
Appears in Collections:[材料工程研究所] 博碩士論文

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