超低温和氯盐作用对超高韧性水泥基复合材料碳化性能的影响

Effect of ultra-low temperature and chloride on carbonation performance of ultra-high toughness cement-based composite

极地地区及海洋环境下的资源开采导致混凝土结构受到低温、碳化和氯离子渗透的共同作用,加剧了混凝土材料及其结构的劣化。超高韧性水泥基复合材料(UHTCC)作为一种新型复合材料,其耐久性是评价其工作性能的重要指标。通过对UHTCC材料在超低温作用和氯离子侵蚀后的快速碳化试验,研究了复杂环境作用下不同纤维体积掺量的UHTCC的抗碳化性能变化规律。结果表明:随着温度的降低,UHTCC材料的抗碳化性能明显降低,温度达到−160℃时其碳化深度最大增加约58.76%,适量的纤维掺入对UHTCC材料的抗碳化性能具有明显的提升作用,而超过最优掺量后其抗碳化性能反而有所降低,同时SEM表明氯离子能够细化混凝土内部孔隙,阻碍CO_(2)在材料内部的进一步扩散。提出了极端复杂环境下UHTCC的碳化深度回归模型,研究结论为UHTCC在复杂环境中的工程应用提供参考。

The exploitation of resources in polar regions and marine environment leads to the joint action of low temperature,carbonation and chloride ion penetration on concrete structures,which aggravates the deterioration of concrete materials and structures.As a new type of composite material,the durability of ultra-high toughness cementitious composite(UHTCC)is an important index to evaluate its working performance.Through the rapid carbonization test of UHTCC material under ultra-low temperature and chloride ion erosion,the change law of carbonization resistance of UHTCC with different fiber volume contents under complex environment was studied.The results show that with the decrease of temperature,the carbonation resistance of UHTCC material is significantly reduced.When the temperature reaches−160℃,the carbonation depth of UHTCC material increases by about 58.76%.The appropriate amount of fiber has a significant effect on the carbonation resistance of UHTCC material.However,the carbonation resistance of UHTCC material decreases when the content exceeds the optimal content.At the same time,SEM shows that chloride ions can refine the internal pores of concrete and hinder the further diffusion of CO_(2 )inside the material.The regression model of UHTCC carbonation depth in extremely complex environment is proposed,and the research conclusion provides reference for the engineering application of UHTCC in complex environment.