Mechanisms of Combined Effects of AAR and Reinforcement Corrosion on Concrete

通过对外源海水和氯化钠溶液对ASR的影响以及有和无NaCl砂浆中ASR化学反应过程的详细实验，可以对氯化钠和海水促进ASR的机理提出新的思路。分析了试样表面不同深度孔隙溶液组成随时间的变化及其与钢筋锈蚀的关系。另一个重要的结果是发现了亚硝酸盐的有效性与含亚硝酸盐砂浆的孔隙溶液组成之间的关系。获得的主要结果总结如下：(1)浸泡360 d后，0.51Mm NaCl溶液中砂浆的Cl-/OH-比大于海水。文石和水镁石致密层的形成可能会阻碍Cl-离子侵入砂浆筒和OH-离子的泄漏。(2)从孔隙溶液组成上看，在反应性钢筋腐蚀程度上要大得多。含骨料的迫击炮是出乎意料的。(3)在砂浆中用更大量的活性骨料代替标准砂，除了一种情况外，钢筋的腐蚀程度较小。含活性骨料砂浆在海水和NaCl溶液中的腐蚀抑制似乎是由于在钢筋周围形成了均匀的ASR凝胶层。

We could propose a new thought on the mechanisms of the promotion of ASR due to sodium chloride and sea water through detailed experiments concerning the effects of externally supplied sea water and sodium chloride solution on ASR and the process of ASR chemical reaction in mortars with and without NaCl. Furthermore, the changes in pore solution composition with time at various depths from the surfaces of specimens and their relation to the corrosion of reinforcement steel bars in the specimens were elucidated. Another important result was a finding on the relation between the effectiveness of nitrites and the pore solution composition in mortars containing the nitrites.The major results obtained were summarized as follows ;(1) The Cl-/OH- ratios in mortars in 0.51Mm NaCl solution were greater than in sea water at 360 daysafter, immersion. The formation of dense layrs aragonite and brucite might hinder the intrusion of the Cl- ions into mortar cylinders and the leakage of OH- ions from them.(2) From a point of view of the pore solution composition, far greater corrosion degree in steel bars in reactive. aggregate-containing mortars was unexpected.(3) Replacement of greater amounts of reactive aggregate for standerd sand in mortars resulted in less degree of corrosion in steel bars except one case. The depression of corrosion in reactive aggregate-containing mortars in sea water and NaCl solution appears to result from the formation of homogeneous ASR gel layrs surrounding the steel bars.