化学-力学耦合作用下混凝土内钢筋蚀坑的演化及分布规律

Evolution and distribution of corrosion pits in reinforcing bars under coupled chemo-mechanical attacks

基于概率与统计知识,对化学-力学耦合作用下钢筋蚀坑的演化及其分布进行研究.结果表明氯盐侵蚀下钢筋蚀坑的演化可分为3个阶段:微观非稳态点蚀形核、细观亚稳态蚀坑、宏观稳态蚀坑.单一氯盐腐蚀作用下形成的宏观稳态蚀坑深度相对较小,而拉应力的引入将加剧钢筋表面化学/物理性质的不均匀,从而导致宏观稳态蚀坑深度较大.在氯盐及其与拉应力耦合作用下,钢筋蚀坑分布均优先满足韦伯分布.在一定的锈蚀环境下,尺度参数与锈蚀率之间呈良好的线性关系,但形状参数则与锈蚀率基本无关.据此建立了基于韦伯分布的蚀坑预测模型,预测值与实测数据符合较好.

Based on the probability theory and mathematical statistics, the evolution and distribution of corrosion pits in reinforcing bars under coupled chemo-mechanical attacks are studied. The results show that the evolution of corrosion pits involves three stages： unsteady pitting nucleation in micro- scale, metastable pitting in meso-scale, and steady-state pitting in macro-scale. Under chloride at- tack, the corrosion pit depth in macro-scales is relatively small. While under the coupled chemo-me- chanical effect, the chemical/physical properties of steel surface become uneven, which leads to lar- ger corrosion pit depth. The pitting depth in reinforcing bars conforms to the Weibull distribution preferentially under either chloride or simultaneous tensile stress and chloride attacks. Under certain corrosion environment, the linear regression model fits the relationship between scale parameter and corrosion rate. However, there is no significant relationship between shape parameter and corrosion rate. A predicting model based on the Weibull distribution is established, and the predicted values and the observed ones are in good accordance.