建設材料 コンクリートの欠陥部に生じる中性化による鉄筋腐食の形態と速度

Abstract

The objective of this study was to analyze comprehensively the corrosion cell formation pattern (macro-cell and micro-cell) and the corrosion rate induced by carbonation in concrete with joints or cracks. First, mortar tests were performed using specimens with model defects that simulated cold joints or bending cracks. Herein three important factors that caused steel corrosion were investigated in detail. These factors were: 1) carbonized location, 2) supply of water and oxygen, and 3) water-cement ratio of mortar. Next, concrete tests were performed using specimens with cold joints and bending cracks. The results obtained in this study were as follows; a) 27 cases of which the carbonized location, supply of water and oxygen, and the water-cement ratio of mortar differed were experimented. As results, the corrosion cell formation pattern and the corrosion rate were comprehensively analyzed based on unified conditions. b) In the case of carbonation-induced corrosion with defects, macro-cell corrosion would be formed regardless of the water-cement ratio. Also, the corrosion rate decreased with the decreasing of water-cement ratio. c) The result b) was confirmed not only in mortar tests but also in concrete tests. d) According to above results, it could be said that the low water cement ratio was excellent in the durability for the steel corrosion, when concrete with defects received the influence of carbonation.