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| Migration law of water and chloride ions in aeolian sand concrete |
| DONG Wei1, FU Qianwang1, LIU Xin2*, WANG Dong1, WANG Xuesong1, JI Yajing1 |
| 1. College of Civil Engineering, Inner Mongolia University of Science and Technology, Baotou, Inner Mongolia 014010, China; 2. Department of Civil Engineering, Ordos Institute of Technology, Ordos, Inner Mongolia 017000, China |
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Abstract To solve the problem of resources shortage of ordinary river sand in northwestern of China, the aeolian sand of Kubuqi Desert is used instead of ordinary river sand as fine aggregate to prepare aeolian sand concrete. The effects of different water-binder ratios and different concentrations of NaCl solutions on the permeation patterns of water and chloride ions in aeolian sand concrete, the chloride ions content was determined by means of stratified borehole powder extraction and chemical titration to explore the connection between water and chloride ions transport under capillary action. The results show that water as a medium of chloride ions transport, the penetration depth of chloride ions is much smaller than the penetration depth of water, the two transport presents non-synchronous. After 28 days of capillary absorption, the water-binder ratio of aeolian sand concrete was 0.55, and the water penetration depth was about twice the chloride ion penetration depth, and the water-binder ratio was 0.45 and 0.4. The water penetration depth of the aeolian sand concrete specimen was about the chloride ion pe-netration depth. 1.5 times. When the capillary absorption of more than 7 days, the water-binder ratio of 0.55 aeolian sand concrete specimens generated a large number of salt crystals inside with a water binder ratio of 0.55, which slows down the rate of water penetration. In the early stage of capillary salt absorption, the internal water and chloride ions penetration depth of the aeolian sand concrete specimen is nearly linear, with the capillary absorption time, the water migration rate inside its matrix decreases, and the chloride ions continues to penetrate deeper by diffusion under the effect of high concentration gradient. When the capillary salt absorption concentration exceeds the critical value of 6%, the chloride ions penetration inside the aeolian sand concrete specimen did not increase with the increase of NaCl concentration. This research can provide a theoretical basis for the research on durability of aeolian sand concrete in water conservancy projects in Northwest of China.
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Received: 12 May 2021
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