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一、前言钢筋混凝土保护层厚度的确定,除在结构上应保证钢筋与混凝土的共同工作外,在耐久性方面还应有效地保护钢筋,使构件在预期使用年限内,不致因为受到各种自然因素的客观影响而发生钢筋锈蚀的危害。我国现行钢筋混凝土结构设计规范对于保护层厚度的规定,与国外比较,考虑耐久性的因素不充分,取值一般偏低。实践表明,处于室外暴露或室内潮湿环境中的某些构件,尚不能满足预期耐久年限的要求。混凝土中钢筋的锈蚀,一般是属于电化学腐蚀过程,其必要条件是钢筋表面呈活化状态且同时存在水和氧。除了氯离子的侵蚀以外,混凝土保护层被完全碳化所导致的碱度降低,是使钢筋表面活化的主要原因。因此,在潮湿或干湿交替的常遇环境
I. Preface The determination of the thickness of the reinforced concrete protective layer, in addition to the joint work of the steel bar and the concrete should be ensured in the structure, and the steel bars should be effectively protected in terms of durability so that the components will not be subjected to various natural conditions within the expected service life. The objective impact of the factors occurs due to the corrosion of the steel bars. China’s existing regulations for the design of reinforced concrete structures require that the thickness of the protective layer be compared with that of foreign countries. Considering that the durability is not sufficient, the value is generally low. Practice has shown that certain components in outdoor exposure or indoor wet conditions are not yet able to meet the requirements for the expected endurance period. Corrosion of rebar in concrete is generally an electrochemical corrosion process. The necessary condition is that the surface of the rebar is activated and water and oxygen are present at the same time. In addition to the erosion of chloride ions, the reduction of alkalinity caused by complete carbonization of the concrete protective layer is the main reason for the activation of the surface of the steel bar. Therefore, in wet or wet and dry alternating environment