碾压混凝土坝体析出物及其对材料耐久性的影响

碾压混凝土坝在材料、结构等方面均不同于普通混凝土坝，因而在坝体表面常出现较为复杂的析出物。本文以一座位于我国南方的碾压混凝土坝作为实例，从现场调查、试样测试、水质特征以及坝体结构等方面探讨了此类析出物的基本性状、形成机理以及对于坝体材料耐久性的影响。分析表明：(1)坝体析出物系坝体渗水对于坝体材料的物理一化学侵蚀作用所致；(2)不同颜色的析出物具有不同的主化学成分；(3)坝体的微结构(如孔、缝、隙等)特征决定了坝体内与形成析出物有关的组分的迁移方式。因而认为，在具较好连通性的缝、隙等部位，有关组分以相对集中的渗漏方式而迁移，由此形成的析出物对于坝体材料的耐久性具有较明显的不利影响。

Study on the Metter Excreted from RCC Dam and Its Effect on Materials' Durability

Since a roller-compacted concrete(RCC)dam is different from a traditional concrete dam in materials and structures,the kinds of excreted metter with more complicated ingredient occur on the surface of the RCC dam.The basic characteristics and mechanisms of the excreted metter and its effect on materials'durability were studied,according to in-situ investigation,sampling,water quality analyzing and others.It is concluded that(1)the excreted metter is fromed due to physico-chemical interaction between the percolated water and the compositive materials of dam;(2)The metter in different color has different major components;and(3)the components are transported in different ways,which are largely controlled by the micro-structures of concrete of the dam.Comparatively,the extreted matter fromed by water leakage rather than seepage might have an more obvious influence on materials'durability.