短切碳纤维在混凝土中的分散性能评估与优化

Evaluation and Optimization of the Dispersion Performance of Short-Cut Carbon Fibers in Concrete

碳纤维增强混凝土应用潜力巨大,目前由于不均匀分散的问题,限制了在工程上的应用。已有研究表明分散剂能促进纤维分散。文中较全面地对比分析了甲基纤维素(MC)、羟丙基甲基纤维素(HPMC)、羟乙基纤维素(HEC)、羧甲基纤维素钠(CMC)等纤维素类分散剂以及聚丙烯酸钠(PAAS)、聚丙烯酰胺(PAM)等聚丙烯酸类分散剂,对0.5%体积掺量的不同长度的短切碳纤维在水溶液和混凝土中的分散效果。采用图像化的数据处理方法实现了对碳纤维分散性的定量化描述,并从分散机理分析了分散剂的性质与分散效果的关联性。结果表明,碳纤维在水溶液和混凝土中的分散规律具有一致性;分散效果从低到高依次为不加分散剂<MC<HPMC<HEC<CMC<PAM<PAAS。分散剂分子链越长、侧链和交联结构越复杂,吸水量越大,最终纤维的分散效果越好。纤维越短,分散性越好。

The potential for carbon fiber reinforced concrete is huge.However,due to the problem of uneven dispersion,its application in engineering is limited.Existing research has shown that dispersants can promote fiber dispersion.In this study,cellulose dispersants were comprehensively compared,such as methyl cellulose(MC),hydroxypropyl methyl cellulose(HPMC),hydroxyethyl cellulose(HEC),and sodium carboxymethyl cellulose(CMC),as well as polyacrylic acid dispersants,such as sodium polyacrylate(PAAS)and polyacrylamide(PAM)on the dispersion effect of short-cut carbon fibers of different lengths with a volume fraction of 0.5%in aqueous solutions and concrete.An image-based data processing method was innovatively adopted to achieve a quantitative description of the dispersion of carbon fibers and analyze the correlation between the properties of dispersants and their dispersion effects from the perspective of the dispersion mechanism.The results show that the dispersion patterns of carbon fibers in aqueous solutions and concrete are consistent;the dispersion effect from low to high is without dispersant<MC<HPMC<HEC<CMC<PAM<PAAS.The longer the molecular chain of the dispersant,the more complex the side chain and cross-linking structure,the greater the water absorption,and the better the final fiber dispersion effect.The shorter the fiber is,the better its dispersion is.