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许多建筑物墙面,尤其是雨篷和墙连接处、屋面排水口处及现浇混凝土梁柱处墙面,也就是施工过程中浇水多、雨后积水排除缓慢或少量存水处的墙面,待墙面干燥时常常出现一层白硝状的物质,一般称这种现象为“泛白”或“泛碱”。厚度一般为2～3mm。严重者一层一层剥落,直接影响建筑物的外观和使用寿命。出现泛白现象的主要原因有两方面。首先是砖内及水泥内贮存的可溶性盐类含量过高,其次是溶解这些盐类的水分的迅速蒸发,两者缺一不可。砖墙在全干状态下,盐类是不会迁析至墙外表面的。由于空气中存在着一定的水份,潮湿空气的流动,施工过程中的施水或雨淋使墙体内的盐类遇水溶解,在气候炎热干燥时,水份蒸发很快,被溶解的盐类通过潮湿而多孔的
Many building walls, especially the joints of awnings and walls, roof outlets, and cast-in-place concrete beams and columns, that is, watering during construction, water accumulating slowly after rain, or small amounts of water On the wall surface, when the wall is dry, a layer of white nitrite-like substances often appears. This phenomenon is generally called “whitening” or “alkaline”. The thickness is generally 2 ~ 3mm. Severe layers delaminated directly affecting the appearance and service life of buildings. There are two main reasons for the appearance of whitening. The first is that the content of soluble salts stored in bricks and cement is too high, followed by the rapid evaporation of water that dissolves these salts. Both are indispensable. When the brick wall is completely dry, salt will not migrate to the outer surface of the wall. Because there is a certain amount of water in the air, the flow of moist air, the application of water or rain during construction, the salt in the wall dissolves in water, and when the climate is hot and dry, the water evaporates quickly and is dissolved. Salts are porous and porous