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通过电化学方法和剖型观察方法研究了不同矿物掺合料(硅灰和粉煤灰)和不同钢筋表面状态(预钝、预锈和未处理)对砂浆试样中的钢筋锈蚀行为的影响。用电化学阻抗谱法测试钢筋的腐蚀速率和与钢筋锈蚀相关的电化学参数。结果表明:硅灰由于发生火山灰反应而明显降低体系的pH值,且硅灰结合氯离子的能力明显弱于粉煤灰,氯离子临界值也低于掺粉煤灰试样。基于以上3个负作用,在短期氯盐侵蚀后硅灰的护筋性不佳,相比而言粉煤灰只要掺量合适可以较好地保护钢筋。钢筋表面若无明显腐蚀坑,预锈处理对钢筋锈蚀影响较小(除掺硅灰试样外);预钝化能降低含矿物掺合料砂浆中钢筋的腐蚀速率,但对无掺合料砂浆试样中的钢筋影响很小。
The effects of different mineral admixtures (silica fume and fly ash) and the surface states of different reinforcing bars (pre-blunt, pre-rust and untreated) on the corrosion behavior of steel bars in mortar samples were studied by electrochemical methods and sectional observation methods . Electrochemical impedance spectroscopy was used to test the corrosion rate of steel bars and the electrochemical parameters related to steel corrosion. The results show that silica fume significantly reduces the pH value of the system due to the volcanic ash reaction, and the ability of silica fume to bind chloride ion is obviously weaker than that of fly ash. The critical value of chloride ion is also lower than that of fly ash sample. Based on the above three negative effects, the protection of silica fume in short-term chloride salt is not good, compared with that of fly ash. Pre-passivation can reduce the corrosion rate of rebar in mineral admixture mortar without any obvious corrosion pits on the surface of rebar. Reinforcement in the mortar sample has little effect.