钢筋再生混凝土电化学除氯效果研究∗

Study on the Effect of Electrochemical Chloride Extraction Effectin Recycled Reinforced Concrete

摘要:

为探究遭受氯盐侵蚀钢筋再生混凝土耐久性修复路径，通过内掺氯盐方式模拟再生混凝土遭受氯盐侵蚀，开展再生混凝土电化学除氯试验，研究再生骨料特征和通电参数对电化学除氯效率的影响。研究表明，采用5~25 mm 再生粗骨料粒径范围的钢筋再生混凝土电化学除氯效率是5~30 mm 粒径范围钢筋再生混凝土的1.36 倍；随再生粗骨料取代率增加，电化学除氯效率增大，取代率达50% 时，钢筋再生混凝土除氯效率较普通混凝土提高约26%；随通电电流密度增大，再生混凝土除氯效率增大，相较1 A/m²，电流密度3 A/m² 时的电化学除氯效率是其1.45 倍，电流密度从1 A/m2增大到2 A/m²，再生混凝土除氯效率增幅比普通混凝土更明显；随除氯时间延长，再生混凝土除氯效率明显增大，相对普通混凝土，再生混凝土前期除氯效率占比更大，7 d 除氯效率是28 d 的51%；基于电化学除氯效率开展影响因素敏感性分析，结果表明，再生骨料取代率的影响大于再生骨料粒径，但电化学除氯时间影响最为明显。

Abstract:

To explore the durability repair pathways of recycled reinforced concrete affected by chlo-ride salt-induced corrosion, an electrochemical chloride extraction (ECE) experiment was carried out.Chloride salts were internally added to simulate the corrosion process, and the effect of recycled aggre-gate characteristics and electrical parameters on ECE efficiency were studied. The results showed thatthe ECE efficiency of recycled reinforced concrete with recycled coarse aggregate sizes of 5 to 25 mmwas 1.36 times higher than that of the concrete with aggregate sizes of 5~30 mm. An increased re-placement rate of recycled coarse aggregate resulted in improved ECE efficiency. At a 50% replace-ment rate, the ECE efficiency was about 26% higher than that of ordinary concrete. As current densi-ty increased during electrification, the ECE efficiency also improved. The ECE efficiency at a currentdensity of 3 A/m² was 1.45 times higher than that at 1 A/m². When the current density increased from 1 A/m² to 2 A/m², the improvement in ECE efficiency was more pronounced for recycled concretethan for ordinary concrete. Extending ECE duration significantly enhanced its efficiency, with recycledconcrete showing a substantially higher chloride removal rate in the early stages compared to ordinaryconcrete. The chloride extraction efficiency within the first 7 days was 51% of that achieved in 28days. Sensitivity analysis of the factors affecting ECE efficiency showed that the recycled aggregate re-placement rate had a greater impact than aggregate particle size. However, ECE duration had themost significant impact.