基于孔结构分析的BFCC单面冻融损伤试验研究

Experimental study on BFCC under single-sided freeze-thaw based on pore structure

采用单面冻融试验,研究了3种不同冻融介质(水、Na Cl溶液、Na_(2)SO_(4)溶液)对玄武岩纤维水泥基复合材料(Basalt Fiber Cement Composites,BFCC)剥落量和动弹模量的影响,并对不同冻融次数的BFCC进行XRD物相分析及微观孔结构测试,从宏观和微观角度探究BFCC的冻融损伤过程。结果表明:随冻融循环次数的增加,不同冻融介质中BFCC剥落量不断增加,相对动弹模量呈现下降趋势。在Na Cl溶液中,随着冻融循环的进行,Ca(OH)_(2)衍射峰的强度显著降低,并出现了明显的Friedel盐衍射峰;在Na_(2)SO_(4)溶液中,冻融初期XRD图谱中已出现明显的石膏和钙矾石衍射峰;随冻融循环次数的增加,BFCC的含气量、气泡间距系数、气泡平均弦长均呈现增加的趋势,而气泡比表面积呈现降低趋势。

The effects of three different freeze-thaw media(water,Na Cl solution,Na_(2)SO_(4) solution)on the flaking amount and dynamic modulus of basalt fiber cement composites(BFCC)were studied by single-sided freeze-thaw test.The BFCC with different freeze-thaw cycles was subjected to XRD phase analysis and microscopic pore structure test to explore the freeze-thaw damage process of BFCC from macroscopic and microscopic perspectives.The results showed that with the increase of the number of freeze-thaw cycles,the amount of BFCC spalling in different freeze-thaw media increased continuously,and the relative dynamic elastic modulus showed a downward trend.In the Na Cl solution,the Ca(OH)_(2) diffraction peak proceeded with the freeze-thaw cycle.The intensity of the Friedel salt is significantly reduced.In the Na_(2)SO_(4) solution,obvious gypsum and ettringite diffraction peaks appear in the XRD pattern at the initial freeze-thaw cycle.The gas content of BFCC increases with the number of freeze-thaw cycles.The bubble spacing coefficient and the average chord length of the bubble all show an increasing trend,while the specific surface area of the bubble shows a decreasing trend.