裂缝对混凝土中水分传输影响研究进展

Review of research progress on water transport mechanism of cracks within concrete

由荷载或环境因素产生的混凝土裂缝,不仅降低了混凝土抵抗水分侵入的能力,还为侵蚀性介质侵入混凝土内部提供附加通道,造成钢筋混凝土结构耐久性不足和使用寿命降低。本文从试验研究和数值模拟两个方面,系统评述了裂缝对混凝土中水分传输影响的研究进展。研究发现,混凝土裂缝中的水分传输系数与裂缝宽度的二次或三次方成正比;裂缝迂曲度的增加能显著降低水分的传输速度;裂缝粗糙度的变化对水分传输速度影响很小;裂缝密度的增加能增大混凝土的吸水量。此外,裂缝的自愈合能够降低水分在混凝土裂缝中的传输速度。研究裂缝对混凝土中水分传输规律的影响可为钢筋混凝土结构的耐久性设计提供理论依据。最后,在总结已有研究成果的基础上,分析了开裂混凝土中水分传输研究存在的问题,并对未来可能的研究方向给出了建议。

Cracking of concrete,which may be induced by mechanical loads or resulted from the exposed environmental action,not only reduces the ability of concrete to resist water penetration,but also provides additional pathways for aggressive media to penetrate into concrete.This process will obviously reduce ser⁃vice life as well as durability insufficiency of reinforced concrete structures.This paper systematically re⁃views the research progress relating to the influence of cracks on water transport within concrete from exper⁃imental research and numerical simulation.The previous studies indicated that water transport coefficient of cracked concrete is proportional to the second or third power of crack width.The increase of crack tortuosi⁃ty can significantly reduce the speed of water transport,while it has little effect by changing the crack sur⁃face roughness.Meanwhile,the water content absorbed of concrete can be increased due to the develop⁃ment of crack density.In addition,the self-healing of cracks exposed to profitable environments can de⁃crease water transport speed in cracks of concrete.Therefore,to investigate the effect of cracking or cracks concrete on water transport mechanisms in concrete will provide the theoretical basis for durability design of reinforced concrete structures.Based on the summary of the existing research results,research expecta⁃tions as well as future priorities associated with water transport mechanisms of the cracked concrete are ar⁃gued and suggested in the final section of the paper.