天然水对水硬性混凝土的侵蚀及其防护第二单元第二讲（续）·第三讲关夫（七）混凝土表层增实混凝土浇捣后由于沙石下沉，水分上升或旁溢，造成析水现象。如石子级配好，最大粒径愈大，沙子较细时，析水较少；反之则大。析水量占拌合水量可达１０～３０％，且水分富有碱性... The erosion and protection of natural water on hydraulic concrete The second unit (Continued) · The third lecture (7) The concrete surface layer of reinforced concrete After the pouring of concrete, due to the sinking of sand and sand, the water rises or overflows. Water analysis. If the stone grading is good, the larger the maximum particle size, the smaller the sand, the less water analysis; otherwise it is large. The amount of precipitation water accounts for 10-30% of the mixing water, and the water is rich in alkalinity...