玄武岩纤维-木纤维复合碱式硫酸镁水泥性能的改性机理

Modification mechanism of basalt and wood fiber composite basic magnesium sulfate cement performance

以碱式硫酸镁水泥(BMSC)为基质,以生物基循环木纤维(RWF)为轻质填料,并掺入玄武岩纤维(BF)为增强改性材料,开发出一种轻质高强、高韧性的碱式硫酸镁复合材料。从RWF填料和不同体积占比、不同长度的BF纤维出发,讨论其对改性后BMSC复合材料的流动性、分散系数(纤维)、密度、抗压强度和抗折强度的影响;通过SEM、EDS、XRD微观表征分析对复合材料微观结构的形成进行研究。结果表明:RWF的加入虽然显著降低了BMSC的材料密度,但RWF与BF结合形成复合纤维体系能明显提升BMSC复合材料的力学性能,尤其是抗折强度,较未添加RWF和BF的原生BMSC材料提升比例最高达80%以上;通过微观表征分析发现,RWF在BMSC中拥有良好的界面黏结性能,RWF与BF的共同存在使BMSC材料形成镁水泥基质-循环木纤维-玄武岩纤维体系,提升了复合材料的强度;采用基于图像识别技术的半定量化方法对碱式硫酸镁水泥5·1·7相晶体的发展程度进行辅助量化分析,为材料制备过程中BMSC产品性能的控制提供可能。

Limited by the differences between cementitious materials and basic magnesium sulfate cement(BMSC),the study of enhancing the toughness and mechanical properties of BMSC products by incorporating bio-based fillers with fibers is still very limited.Through different mix design,wood fiber and basalt fiber(BF)were used as lightweight fillers and reinforcements of BMSC materials.The fluidity,dispersity(fiber),density,compressive strength and flexural strength of modified BMSC were tested.The typical samples were characterized by SEM,EDS and XRD.The results showed that the addition of wood fiber significantly reduces the density of BMSC,and the combination of wood fiber and BF can significantly improve the mechanical strength,especially the flexural strength,with the maximum increase rate of more than 80%.By microscopic characterization,it was found that wood fiber has good mixed compatibility with plant materials in BMSC.The combination of wood fiber and BF forms a magnesium cement matrix-wood fiber-BF model,which significantly improves the strength of the composite reinforcement.A semi-quantitative method based on image recognition technology was attempted,and it was found that the development degree of hydration products crystals could be analyzed quantitatively.It provides the possibility to control the performance of BMSC products during material preparation.