仿生高韧水泥基复合材料制备技术及增韧机理

Preparation technology and toughening mechanism of a bionic high-toughness cement-based composite

为了提升混凝土基体的韧性,基于贝壳珍珠层独特“砖-泥”结构,采用水泥石与有机聚合物制备出具有仿生“砖-桥-泥”结构的高韧水泥基复合材料.通过三点弯曲试验、扫描电子显微镜及有限元模拟方法研究了仿生水泥基材料的抗折强度、韧性及增韧机理.结果表明,相较于传统水泥的脆性断裂模式,仿生水泥基材料表现出明显的延性断裂特征,包括峰后曲线渐进下降、跨中挠度大幅增加等.基于有机聚合物的多尺度桥接-伸展效应,仿生水泥基材料内部呈现明显的裂纹偏转及分支现象,体现了仿生“砖-桥-泥”结构的内外协同增韧机制.仿生水泥基材料能够在保证95%抗折强度的基础上,将水泥基体的韧性提高179.45%,可为解决混凝土增韧降脆问题提供新的技术路径.

To enhance the toughness of the concrete matrix,based on the unique“brick-mortar”structure of shell nacre,a bionic high-toughness cement-based composite material with“brick-bridge-mortar”structure was prepared using cement stone and organic polymers.The flexural strength,toughness,and toughening mechanism of bionic cement-based materials were studied by three-point bending test,scanning electron microscopy and finite element simulation.The results indicate that compared with the brittle fracture mode observed in conventional cement,bionic toughened cement-based materials exhibit evident ductile fracture properties,including a gradual reduction in the post-peak curve and a significant augmentation in mid-span deflection.Based on the multi-scale bridging-stretching effect of organic polymers,the bionic toughened cement-based materials exhibit clear crack deflection and branching phenomena internally,which reflects the internal and external collaborative toughening mechanism of the bionic“brick-bridge-mortar”structure.These materials can increase the toughness of the cement matrix by 179.45%,while ensuring 95%flexural strength.This finding offers new technique route to solve the problem of enhancing toughness and reducing brittleness in concrete materials.