基于混凝土裂缝特征的氯离子传输性质研究进展

Review of Chloride Transport Properties in Concrete Featured with Different Cracking Characteristics

介绍了混凝土裂缝的诱导试验方法和已开裂混凝土中氯离子传输的试验方法、表征手段及传输性质的影响因素。对比分析了机械力学破损法和非机械力学无损法的差异,阐述了裂缝宽度、裂缝深度、水胶比、水泥与矿物掺合料及其外加剂的含量、保护层厚度、环境氯离子溶液浓度及暴露周期、荷载作用对已开裂混凝土中氯离子传输性质的影响,并对氯离子的传输机理与性质的研究进行了展望。对于混凝土裂缝诱导试验方法,非机械力学无损法适合于定量研究不同裂缝特征对混凝土传输性质的影响,但需建立人造裂缝与实际工程裂缝在混凝土传输性质上的相关性。小于100μm的裂缝宽度对混凝土中氯离子传输速率的影响显著;当裂缝宽度大于100μm时,混凝土中氯离子的传输速率变化较小。此外,较高的裂缝深度与水灰比均对混凝土中氯离子传输速率的增加有明显促进作用,但是增加水泥用量与掺加适量矿物掺合料,可减缓已开裂混凝土中氯离子的传输速率。

This paper reviews the test methods to induce concrete cracking,experimental and characterization methods for chloride transport in cracked concrete and influencing parameters.For these methods of crack preparation,there is a difference between destructive and non-destructive methods to form artificial cracks.The effect of influencing parameters like crack width and depth,ratio of water to cement,cement content,supplementary materials,additive,cover thickness,load,chloride concentration and exposure duration on the chloride transport properties based on some previous work was represented.In addition,some prospects were given to investigate the transport mechanism and the property of cracked concrete in future.For the test methods to induce concrete cracking,the non-destructive method can be used to quantitatively study influence of different cracking parameters on transport properties of concrete.However,it should be established the transport property relationship between artificial and real engineering cracks.As the width is 100 μm below,crack made significant contribution for transport rate of chloride ions.By contrast,crack with a width of higher than 100 μm shown slight effect on the transport rate.In addition,high value of crack depth and ratio of water to binder contributed to the transport rate,while increase of cement amount and addition of mineral admixture can reduce the transport rate.