【摘要】 为分析冻融循环和应力水平对混凝土结构碳化深度的影响,设计并实施了不同应力钢筋混凝土试件纯碳化试验和冻融-碳化交替试验。以Papadakis的经典碳化理论模型为基础,结合冻融和应力对混凝土CO₂扩散性能的影响,以混凝土中可碳化物质在碳化过程中各物质质量平衡为条件建立微分方程,使用COMSOL Multiphysics建立考虑冻融和弯压应力的钢筋混凝土试件碳化深度模型,比较数值模拟结果与试验结果。结果表明,压应力和冻融分别会提高和降低混凝土的抗碳化能力;当混凝土受力状态由受压变为受拉时,应力-冻融耦合对混凝土的碳化由抑制转换为促进作用,确定不同冻融条件及混凝土类型下的冻融临界应力,有助于对冻融环境下混凝土碳化进行有效防护;基于COMSOL Multiphysics的有限元分析结果和实测结果吻合较好,可为冻融和应力下混凝土构件碳化深度预测分析提供依据。更多还原

【Abstract】 To analyze the effect of freeze-thaw cycles and stress level on carbonation depth of concrete structures, pure carbonation tests and free-thaw-carbonation alternation tests of reinforced concrete specimens under different stress levels were designed and implemented. Based on classical carbonation theory model proposed by Papadakis and combined with the effect of freeze-thaw and stress on the diffusion of CO₂ in concrete, the differential equation was established under the condition of mass balance of carbonated substances in concrete during carbonation. The reinforced concrete specimens under the condition of freeze-thaw and compress-bend stress were established by COMSOL Multiphysics, and the finite element analysis results were compared with the tested results. The results show that compressive stress and freeze-thaw can inhibit and promote carbonization of concrete, respectively. When the stress state of concrete changes from compression to tension, the stress-freeze-thaw coupling effects on concrete carbonation changes from inhibition to promotion. It is helpful to ensure the critical stress of freeze-thaw cycles under different freeze-thaw conditions and concrete types, so as to prevent the concrete to carbonate under freeze-thaw conditions. The results of finite element analysis based on COMSOL Multiphysics are well consistent with the tested results, which can provide the basis for prediction and analysis of the carbonation depth of concrete components under the coupling effects of freeze-thaw cycles and stress.更多还原