碳纳米纤维混凝土抗盐-冻性能研究  

Study on Salt-Frost Resistance of Carbon Nanofiber Concrete

作　　者：王钧[1] 王珊[1] 董浩 WANG Jun;WANG Shan;DONG Hao(School of Civil Engineering and Transportation,Northeast Forestry University,Harbin 150040,China)

机构地区：[1]东北林业大学土木与交通学院,哈尔滨150040

出　　处：《森林工程》2024年第4期175-185,共11页Forest Engineering

基　　金：黑龙江省交通投资集团项目(HKF220500004)。

摘　　要：为研究碳纳米纤维混凝土在盐-冻融循环作用下的抗冻性能变化规律,以3.5%NaCl溶液作为冻融循环介质,对4种不同碳纳米纤维(CNFs)质量掺量(0%、0.1%、0.2%、0.3%)的混凝土试件进行快速冻融循环试验,通过扫描电镜、X射线衍射和氮气吸附等微观测试手段分析纤维改性机理,并建立冻融损伤模型以评价盐-冻融循环条件下碳纳米纤维混凝土的损伤演化规律。结果表明,CNFs可提高混凝土抗盐-冻性能,改善效果与碳纳米纤维掺量呈正相关,质量掺量为0.3%时抗冻等级及耐久性指数较基准组提高100%。CNFs通过桥接裂缝、控制纳米级裂纹、成核、改善孔结构提高混凝土密实度,进而改善混凝土的抗盐-冻性能。基于不同评价指标建立的冻融损伤模型符合威布尔分布且R2均大于0.9,可用于评价和预测盐-冻融循环条件下碳纳米纤维混凝土损伤情况。In order to study the change rule of frost resistance of carbon nanofiber concrete under the action of salt-freeze-thaw cycle,the concrete specimens with four different carbon nanofibers(CNFs)mass admixture(0,0.1%,0.2%,0.3%)were subjected to rapid freeze-thaw cycling test using 3.5%NaCl solution as the freezing and thawing cycling medium.The fiber modification mechanism was analyzed by scanning electron microscopy,X-ray diffraction,nitrogen adsorption and other microscopic technical means.Moreover,a freeze-thaw damage model was developed to evaluate the damage evolution of carbon nanofiber concrete under salt-freeze-thaw cycling conditions.The results indicated that CNFs could improve the salt-frost resistance of concrete,and the improvement effect was positively correlated with the dosage,and the freezing-resistance grade and durability index were increased by 100%compared with the baseline group at a mass dosage of 0.3%.CNFs enhanced the compactness of concrete by bridging cracks,controlling nanoscale cracks,nucleation,and improving pore structure,which in turn improved the salt-frost resistance of concrete.The freeze-thaw damage models established based on different evaluation indexes conform to the Weibull distribution and had R2 greater than 0.9,which can be used for evaluating and predicting the damage of carbon nanofiber concrete under salt-freeze-thaw cycle conditions.

关 键 词：碳纳米纤维 超细粉煤灰 盐-冻融循环 机理分析 损伤模型 

分 类 号：TU592[建筑科学—建筑技术科学]