应力状态下混凝土的碳化试验研究

Experiment and research of presteressed concrete structure in carbonation corrosive environments

进行了碳化环境下预应力混凝土试件的耐久性试验研究 ,阐述了在应力和碳化共同作用下的混凝土结构破损机理及规律 .试件为无应力、弯曲受拉和直接受压的应力状态 ,采用加速碳化的试验方案 .分别引进kwc和 χσ 反映碳化深度与混凝土质量、强度和应力水平的关系 ,建立了应力状态下的混凝土碳化深度的多因素预测模型 .结果表明 :拉、压应力分别加快和减缓了混凝土的碳化速率 ,且应力越大 ;碳化速率的改变越大 ;χσ 可以反映碳化速率的变化趋势 .施加预应力能够控制混凝土裂缝的发展、消除或限制裂缝的宽度 ,因此 ,预应力混凝土结构的耐久性比普通混凝土结构的耐久性更好 .

The durability experiments of prestressed concrete specimens in carbonation corrosive environments were carried out. The corrosion mechanism of concrete under the coactions of stress and carbonation corrosion was discussed. The specimens were categorized into three types: non-stressed, bend-tensile stress and compressive stress. Carbonation of the specimens was accelerated. A multi-factor model forecasting the carbonation depth of prestressed concrete was constructed, introducing k wc and χ σ , which describe the relationships between carbonation depth and concrete quality or strength or stress levels. The results show that the tensile stress and compressive stress are able to accelerate or slow down the concrete carbonation, respectively, and the larger the changes in stresses, the larger the changes in carbonation degrees. χ σ reflects the changes well. The compressive stress can control the development of concrete cracks, and eliminate the crack width, so the durability of the prestressed concrete structure is better than that of an ordinary concrete structure.