工程实践及试验研究表明,规范TJ10—74规定的混凝土保护层最小厚度(表1),对绝大多数室内构件能满足要求;但对露天和室内有蒸汽情况下使用20～50年构件的调查表明,由于保护层偏薄,较普遍地出现钢筋锈蚀,产生了沿筋纵向裂缝或混凝土剥落,影响了结构的耐久性。为此,提出了修订混凝土保护层最小厚度取值的建议: 混凝土保护层最小厚度(毫米) 表1 Engineering practice and experimental studies have shown that the minimum thickness of the concrete protective layer specified in TJ 10-74 (Table 1) meets the requirements for most indoor components; however, the investigation of 20 to 50-year components in open and indoor steam conditions It shows that due to the thin protective layer, corrosion of steel bars occurs more commonly, resulting in longitudinal cracks along the ribs or spalling of concrete, which affects the durability of the structure. To this end, proposals have been made to revise the minimum thickness of the protective layer of concrete: Minimum thickness of concrete protective layer (mm) Table 1