以脈衝電流法量測混凝土中鋼筋腐蝕劣化之研究

Reinforcement Corrosion in Concrete Measured by Galvanostatic Pulse

鋼筋混凝土為現今土木工程大量使用，如何評估其耐久性為重要的研究課題之一。其中，鋼筋腐蝕關係到結構物的力學及耐震性能評估，但目前量測技術仍具有相當地不確定性，量測結果不全然反應實際鋼筋腐蝕的情形。有鑑於此，本計畫探討混凝土中鋼筋腐蝕的量測技術，同時利用小尺寸及足尺寸試體，比較直流極化法與脈衝腐蝕量測法，探討影響量測鋼筋腐蝕電流的因子。結果發現，脈衝腐蝕量測法較直流極化法更能準確計算腐蝕量。其中，計算腐蝕量約與重量損失成正比，但兩者關係受到保護層水灰比、保護層厚度、保護層粗細粒料比例及鋼筋配置影響。欲得到可靠量測值，試體必須保持面乾飽和，不具表面披覆，量測前必須先界定主筋與箍筋位置，量測時必須區分箍筋間與鋼筋疊置處分別量測。

Reinforced concrete is widely used in civil engineering nowadays, and its durability is one of the research focuses. Among all the durability issues, the corrosion of the reinforcement is drawing more and more attentions since it is associated with the mechanical and seismic performance of reinforced concrete structure. However, the modern measurement techniques have limitations and the results show great uncertainties. In view of these issues, this study explores the factors influencing the reinforcement corrosion measurements in reduced or full-scaled concrete specimens using the linear polarizations and the galvanostatic pulses. Results show that the galvanostatic pulse provides more accurate results than the linear polarization. The calculated weight loss through the measurements is proportional to the weight loss, but their linear relationships are influenced by the water-cement ratio of the cover, thickness of the cover, the ratio of the coarse to fine aggregates of the cover, and the arrangement of the reinforcement. To obtain reliable results, specimens must be in saturated surface dry and have no coatings. The locations of the stirrups and the main bars must be identified in advance and then the corrosion measurements must be conducted at those locations separately.