粘土固化型微胶囊复合水泥基材料的设计与力学损伤自修复行为

Design and self-repair behavior of clay-cured microcapsule composite cementitious materials

采用圆锅造粒法,通过对微胶囊工艺与配方参数进行设计和优化,制备了以粘土固化剂、膨润土、MgO膨胀剂和微晶纤维素为芯材,以乙基纤维素(EC)为壁材的微胶囊,采用正交试验探索了微胶囊芯材组分对自修复微胶囊/水泥基复合材料自修复效果的影响并确定了微胶囊芯材的最佳组成为:粘土固化剂为10wt%、MgO膨胀剂为35wt%、微晶纤维素为6wt%,膨润土为49wt%。研究结果表明,随着微胶囊掺量的增加,自修复水泥基材料的抗压强度降低,当微胶囊掺量(占水泥质量)为3%时,自修复微胶囊/水泥基复合材料的抗压强度相较于空白组仅下降了4%且具有较高的强度恢复率为103.8%。通过数字散斑相关方法(DSCM)对加载过程中的自修复微胶囊/水泥基复合材料的变形行为进行了追踪测试。从应力-应变曲线、应变场分布、灰度相关系数特征值(S_(tc))和应变特征值(S_(ts))之间的变化规律,得出自修复微胶囊/水泥基复合材料的自修复机制,基于微胶囊破裂时产生了与水泥基同源物质钙钒石(AFt)和Mg(OH)_(2)对裂纹进行填补,限制裂纹发展,达到修复裂纹的目的。

Using the round pot granulation method,through the design and optimization of the microcapsule process and formulation parameters,microcapsules with clay solidifying agent,bentonite,MgO expansion agent and microcrystalline cellulose as the core material and ethyl cellulose(EC)as the core material were prepared.For the microcapsules of the wall material,the influence of the components of the microcapsule core material on the selfhealing effect of the self-healing microcapsule/cementitious composite material was explored by orthogonal experi ments,and the optimal composition of the microcapsule core material was determined:That is,the clay curing agent is 10wt%,MgO expansion agent is 35wt%,microcrystalline cellulose is 6wt%,and bentonite is 49wt%.The results show that the compressive strength of self-healing microcapsule/cementitious composite decreases with the increase of the content of microcapsules.When the content(mass to cement)of microcapsules is 3%,the compressive strength of self-healing microcapsule/cementitious composite is only dropped by 4%with a high strength recovery rate of 103.8%.The deformation behavior of self-healing microcapsule/cementitious composites during loading was traced and tested by the digital speckle correlation method(DSCM).From the stress-strain curve,strain field distribution,gray correlation coefficient eigenvalues(S_(tc))and strain eigenvalues(S_(ts)),the self-healing mechanism of self-healing microcapsule/cementitious composite is based on the fact that when the microcapsules rupture,the cement-based homologous substances(AFt,Mg(OH)_(2))are generated to fill the cracks,limit the development of cracks,and achieve the purpose of repairing cracks.