水泥基材料超低温冻融循环试验研究

利用液氮作为环境介质进行超低温冻融循环试验，研究了超低温对水泥基材料抗冻性能的影响。观测冻融循环前后试件外观、质量和强度等宏观性能变化，采用扫描电子显微镜（SEM）分析水泥基材料冻融循环前后微观结构变化。试验结果表明：在超低温条件下，混凝土的抗冻性能明显强于砂浆，且随混凝土强度提高其抗冻性能呈增长趋势；SEM分析结果表明超低温冻融循环后泡水融化试件结构内存在明显缺陷；超低温冻融循环试验可以加速水泥基材料破坏进程，明显减少试验周期，能相对较快的评价出水泥基材料的抗冻性能。

Experimental Analysis of Freeze thaw Recycle With Ultra Low Temperature for Cementitious Material

This investigation focuses on influence of ultra-low temperature on frost-resistance of cementitious material by freeze-thaw cycles test in which liquid nitrogen was applied as ambient medium. The appearance, mass and strength change before freeze-thaw recycle and after were measured, respectively. Micro-structure of cementitious material before and after freeze-thaw recycle was tested by using scan electron microscope （SEM）. It is found that, under the condition of ultra-low temperature, frost resistance of concrete is better than that of mortar. And the frost resistance of concrete increased with the improvement of concrete strength. The SEM results reveal the structure defect is produced clearly when specimen freeze in liquid nitrogen and thawed in water. It is concluded that freeze-thaw recycle with ultra-Low temperature is an effective quick method to evaluate the frost resistance of cementitious material because destroying progress was accelerated and experimental time was redned.