| 摘要: |
| 为模拟混凝土内部与盐溶液接触、外部与空气接触的半浸泡环境(如隧道衬砌混凝土所处环境),将混凝土一端与Na2SO4溶液接触,另一端暴露在空气中,通过改变环境相对湿度、水灰比和Na2SO4溶液质量分数,分析这3种因素对混凝土水分蒸发速率的影响,对混凝土内部的盐溶液传输机理是否符合灯芯效应传输原理进行验证;同时采用核磁共振(NMR)和X射线衍射(XRD)分析,从微观角度分析其中原因.结果表明：环境相对湿度越低、水灰比越大,混凝土水分蒸发速率越大;Na2SO4溶液质量分数越大,混凝土水分蒸发速率反而越低,说明当混凝土处于半浸泡环境下时,其中的Na2SO4溶液传输过程并不符合灯芯效应传输原理.NMR和XRD分析发现,在盐溶液传输过程中,混凝土孔隙内的盐溶液会发生化学反应,生成钙矾石和石膏等化学侵蚀产物,细化和堵塞孔隙,且环境相对湿度越大、盐溶液质量分数越大,化学反应程度越大,从而造成其中的水分蒸发速率降低越明显. |
| 关键词: 混凝土 半浸泡 灯芯效应 化学侵蚀 盐结晶 |
| DOI：103969/j.issn.1007 9629202004008 |
| 分类号: |
| 基金项目:国家自然科学基金资助项目(51378058) |
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| Transport Process of Solution in Concrete Partially Immersed inNa2SO4 Solution |
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LIU Zanqun1, PEI Min1, LIU Hou2, ZHANG Fengyan1, ZHU Jiahui1
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1.School of Civil Engineering, Central South University, Changsha 410075, China;2.Hunan Testing Insititute of Product and Commodity Supervision, Changsha 410075, China
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| Abstract: |
| Transport process of Na2SO4 solution in partially immersed concrete, where the upper surface of concrete contacts the solution and the bottom surface contacts air(like tunnel lining concrete), was stimulated, and the effects of relative humidity(RH), water cement ratio(mW/mC) and concentration of Na2SO4 solution on the evaporative ratio were observed. The test results show that lower RH and larger mW/mC cause faster evaporative ratio, but higher concentration of solution hinders water evaporation. These results cannot be reasonably explained by the classic theory of wick action. Micro analysis by NMR and XRD, shows that the formation of ettringite and gypsum due to chemical sulfate attack block the pores in the concrete and decrease the evaporative ratio. Higher concentration solution and higher RH condition can result in stronger chemical reactions and lower evaporative ratio. |
| Key words: concrete partially immersed wick action chemical attack salt crystallization |
