碳化对带裂缝混凝土中钢筋腐蚀的影响

Effect of Carbonization on Corrosion of Steel Bars in Concrete with Cracks

摘要:

为探究碳化作用下带裂缝混凝土中钢筋的腐蚀特征，通过控制裂缝参数，研究了带裂缝硬化水泥浆体的碳化规律，分析了碳化作用下带裂缝硬化水泥浆体中钢筋的腐蚀面积率、失重率和电化学腐蚀参数特征.结果表明：养护早期带裂缝水泥硬化浆体的裂缝宽度相较于水灰比对钢筋腐蚀的影响更为显著，养护后期裂缝宽度对钢筋腐蚀的影响仍逐渐增加，并占主导地位；碳化作用下带裂缝水泥硬化浆体的Nyquist图存在2个容抗弧，其中低频区容抗弧随着碳化龄期的增加逐渐收缩，钢筋表面双电层的传递电阻降低，钢筋开始脱钝；在一定的裂缝宽度范围内，较小的水灰比可以抑制硬化水泥浆体中的钢筋腐蚀.

Abstract:

In order to explore the corrosion characteristics of steel bars in cracked concrete under carbonation， the carbonation law of hardened cement pastes with cracks under carbonation was studied by controlling crack parameters， and the corrosion area rate， weight loss rate and electrochemical corrosion parameter characteristics of steel bars in hardened cement pastes with cracks were clarified. The results show that the crack width of the hardened cement paste with cracks in the early stage of curing has a more significant effect on the corrosion of steel bars than the water-cement ratio， and the influence of the crack width on the corrosion of steel bars gradually increases and plays a dominant role in the later stage of curing. There are two capacitive arcs in the Nyquist diagram of a cracked hardened cement paste under carbonization. As the age of carbonization increases， the capacitive arc resistance in the low-frequency region gradually shrinks， the transfer resistance of the electric double layer on the surface of the steel bar decreases， and the steel bar begins to remove the passivate film. Within a certain range of crack width， when the water-cement ratio is small， the corrosion of steel bars in hardened cement pastes can be suppressed.