碳酸钙晶须对SHCC性能的影响  

Effect of calcium carbonate whisker on SHCC properties

作　　者：宋梦凡 王金邦[1,2] 栾从起 周宗辉 SONG Mengfan;WANG Jinbang;LUAN Congqi;ZHOU Zonghui(Shandong Provincial Key Laboratory of Preparation and Measurement of Building Materials,University of Jinan,Jinan 250022,China;Shandong Institute of Ecological Environment Co.,Ltd.,Jinan 250022,China)

机构地区：[1]济南大学建筑材料制备与测试技术重点实验室,山东济南250022 [2]山东省生态环境研究院有限公司,山东济南250022

出　　处：《混凝土》2022年第3期14-19,共6页Concrete

基　　金：国家自然科学基金项目(51872120);国家重点研发计划项目(2017YFB0309905);国家高技术研究发展计划(863计划)(2015AA034701);先进水泥基材料国际合作项目(D17001)。

摘　　要：硬化水泥基复合材料(SHCC)是一种多相多尺度的高延性水泥基材料,常用的纤维通常为单一尺度的厘米长度的纤维,不能很好的实现对微米尺度裂缝的阻裂,厘米尺度纤维混杂微米尺度纤维可实现梯度阻裂效果。采用了微米尺度的碳酸钙晶须(CW)与厘米尺度的PVA纤维混杂制备SHCC材料,研究了CW对力学性能的影响,并通过SEM、TG-DTG、X射线衍射(XRD)等测试对CW增韧机理进行研究。结果表明,微米尺度的CW通过晶须桥连微裂缝,晶须拔出消耗能量,提高SHCC力学性能,发挥多尺度阻裂效果。与对照组相比,掺有2%CW试样的抗折强度和抗压强度分别提高20.9%、18.6%,薄板试样在四点弯曲载荷下呈现多缝开裂特征,展现出弯曲硬化现象。此外,CW的加入诱导一种水化产物-单碳酸盐的出现,其硬度和体积均大于单硫型水化硫铝酸钙(AFm),有利于力学性能的提高。Strain hardening cementitious composites(SHCC)was a kind of high ductility cement-based material with multi-phase and multi-scale.However,the commonly used fibers were usually centimeter-length fibers of a single scale.The resistance to micrometer scale crack was not well realized.Centimeterscale-micron scalehybrid fibers could achieve the effect of gradient crack resistance.Micron-scale calcium carbonate whisker(CW)with centimeter-scale PVA fiber were used to prepare SHCC material.The effect of CW on mechanical properties was studied.The toughening mechanism of CW was studied by SEM,TG-DTG and X-ray diffraction(XRD)tests.Results showed that CW in micron scale connects micro-cracks through whisker bridge,and whisker pulling consumes energy,improved mechanical properties of SHCC.CW gave full play to multi-scale crack resistance effect.Compared with the control group,the flexural strength and compressive strength of the sample mixed with 2%CW increased by 20.9%and 18.6%,respectively.In addition,the sheet specimens exhibited the characteristics of multi-crack cracking under four-point bending load and exhibited the phenomenon of bending hardening.Moreover,the addition of CW induced the emergence of a kind of hydration product-monocarbonate,which hardness and volume were larger than AFm,which was beneficail to the improvement of mechanical properties.

关 键 词：碳酸钙晶须(CW) 应变硬化水泥基复合材料(SHCC) 混杂纤维 力学性能 水化产物 

分 类 号：TU528.01[建筑科学—建筑技术科学]