聚羧酸减水剂对水泥基材料中碳纤维分散性的影响

Effect of polycarboxylate superplasticizer on dispersion of carbon fiber in cement-based material

通过简单有效的技术措施提高碳纤维在水泥基材料中的分散性有助于提高其应用效果。通过浊度法对比了碳纤维在聚羧酸减水剂(PC)和甲基纤维素(MC)溶液中的分散效果,测试了碳纤维增强水泥砂浆(CFRM)的电阻率和孔结构,并采用扫描电镜观测碳纤维增强水泥砂浆(CFRM)中碳纤维分布情况。结果显示,PC浓度提高不同长径比的碳纤维分散性明显改善,配制的CFRM导电性显著增加;而甲基纤维素仅对长径比小的碳纤维有较好的分散效果,CFRM导电性仅在水灰比较高时有提升;萘系减水剂溶液分散后的碳纤维所配制的CFRM导电性无明显变化。PC具有良好的碳纤维分散效果在于PC极性基团吸附在碳纤维表面,导致纤维表面斥力增加,有效改善了碳纤维的分散性;扫描电镜观察和孔结构分析均证实PC对碳纤维有良好的分散效果。

Improving the dispersion of carbon fiber with simple technical methods was helpful to enhance its ap- plication effect. In this paper, the dispersion of carbon fiber in solutions of an esters polycarboxylate superplas- ticizer（PC） and methyl cellulose（MC） was investigated by measuring turbidity; the influence of the dispersing agents on the electrical resistivity and pore structure of carbon fiber reinforced mortar （CFRM） was tested and uniformity of the distribution of carbon fiber was observed using a scanning electron microscope. The results show that the carbon fibers with different length-diameter ratio were dispersed uniformly in the PC solution and the electricity of resulting CFRM increased significantly; but only carbon fibers with small length-diameter ratio did in the MC solution and iust the electricity of CFRM with high water-cement ratio increased to some extent. By contrast, the electricity of CFRM made from water reducer FDN, which improved the fluidity, had no sig- nificant increase. It is suggested that the water reducer PC had a amount of polar groups adsorbed by the sur- face of the carbon fiber and increased the repulsion between carbon fibers, therefore improved the dispersion of the carbon fiber in CFRM along with improved the mechanical properties of CFRM. The observation of SEM images and analysis confirmed the positive effect of PC on the dispersion of carbon fiber in CFRM.