A Hypothesis for Salt Frost Scaling in Cementitious Materials
A Hypothesis for Salt Frost Scaling in Cementitious Materials
复制标题
胶凝材料中盐霜结垢的假设
DOI：
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发表时间：
2015
期刊：
影响因子：
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通讯作者：
W. Hansen
中科院分区：
文献类型：
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作者：
Zhichao Liu;W. Hansen
在这项研究中，冻结特性进行了实验研究充分引气胶凝材料（功率的间距系数为60-160 µm之间）的变量，包括水胶比（w/B），矿渣水泥添加量和广泛的空气含量。结果证实，低温抽吸作为外部水分进入表面区域的主要运输模式，以放大其中毛细孔中的连续冰生长。这会导致孔隙压力增加，最终导致表面结垢。确定了三个关键因素来控制这种低温抽吸机制：（I）毛细管中的初始冰成核和（II）通过（III）毛细管网络输送的未冻水分的存在。空气夹带，虽然需要保护内部的霜冻损害，在提高混凝土的抗结垢性，并没有产生额外的收益，是一致的毛细吸力占主导地位的结垢机制。在孔隙溶液中添加盐抑制了冰的成核和随后的生长，这可以解释贝西姆效应。
In this study freezing characteristics was investigated experimentally on adequately air-entrained cementitious materials (Powers’ spacing factor is between 60-160 µm) with variables including water-binder (w/b) ratio, slag cement addition and a wide range of air content. Results confirm cryogenic suction as the primary transport mode of the external moisture into the surface region to amplify continuous ice growth in capillary pores therein. This leads to pore pressure build-up and eventually surface scaling. Three key factors are identified to govern this cryogenic suction mechanism: (I) the initial ice nucleation in capillary pores and (II) the presence of unfrozen moisture transported through (III) the capillary network. Air entrainment, although needed for protecting internal frost damage, yields no added gain in improving scaling resistance in concrete and is consistent with the capillary suction dominated scaling mechanism. Addition of salt in the pore solution suppresses the ice nucleation and subsequent growth which may explain the pessimum effect.