鋼筋混凝土腐蝕對握裹力影響之研究

The Effect of Steel Corrosion on Bond Strength of Reinforced Concrete

本研究係針對鋼筋腐蝕後對握裹力影響之研究，試驗變數包括水灰比及防蝕處理等。研究分析顯示，當鋼筋間距大於4倍保護層厚度或其側向保護層大於2倍底部保護層厚度時，鋼筋腐蝕後混凝土之龜裂模式，可能呈放射狀剝落，反之，則呈片狀剝落現象。鋼筋因腐蝕之重量損失率與握裹強度成負效應，當重損失達1.7%時，將危害結構物之安全性。以微觀檢測分析得知，握裹界面處有孔隙或鐵銹時易成為微裂縫之起源，此類微裂縫與骨材邊緣泌水生成氫氧化鈣層片狀晶體會影響到握裹效應。

The study is mainly aimed at the effect of steel corrosion on bond strength of reinforced concrete. The parameters involoved are w/c and corrosion prevention strategies, etc. The result indicated when clear distance between reinforced steel was over 4 times of concrete cover thickness or the lateral protective layer was over 2 times as concrete cover thickness, the crack pattern of concrete after corrosion would be radial fracture; if not so, it would be spalling fracture. The rate of weight loss and bond strength of corrosion was in inverse relation; hence, when weight loss rate was up to 1.7%, the structure safety would be damaged. Learning from the mi crostruction study, if there was a pore or rust in the bond interface, it was liable to be the source of micro crack. These microcracks and the calcium hydroxide crystal from bleeding in aggregate boundary would affect the bond stress.