摘要
水泥基复合材料作为一种重要的土木工程材料,在国民经济建设中起着举足轻重的作用。目前人们对于其力学性能的研究主要集中于抗压、抗折等宏观力学性能,相比之下,对其微观力学性能的研究较少。鉴于材料的宏观力学性能很大程度上依赖于其微观结构及微观力学性能,因此,从微观层面去探究水泥基材料的性能机理已成为目前研究的热点之一。随着材料微观测试技术的发展,目前纳米压痕技术已成为最先进的定量表征水泥基材料微观力学性能的测试手段。然而水泥基材料是一种非均质材料,其水化产物含有多种成分,导致人们在物相划分和定量分析时常常受到经验性的束缚,因此水泥基材料的性能远未达到人们预期的要求。通过极大似然或最小二乘法对压痕数据进行解卷积处理,可实现实验结果定量化,大大地改变了之前人为划分物相引起的不准确性的状况,使得研究问题的方法提升到一个新的高度。纳米压痕技术不仅可以测试水泥熟料成分(硅酸三钙(C 3S)、硅酸二钙(C 2S)、铝酸三钙(C 3A)等)的弹性模量和硬度,还可测试水泥基材料水化产物(不同密度的水化硅酸钙凝胶(C-S-H)、氢氧化钙(CH)等)的微观力学性能及水化产物未填充的孔隙。通过改变实验加载制度,尤其是持荷的停留时间,能够在很短的时间内测得微观蠕变模量并且可以定量预测水泥基材料的宏观徐变性能;将其与其他微观测试手段(SEM、EDS等)联用来揭示水泥基材料紧密混合相的微观力学性质,能够区分出具有强烈重叠微观力学性质的化学相,这使得纳米压痕技术成为更精确的物相分析方法;通过观测界面过渡区微观结构的变化情况,可以为界面过渡区强度理论提供一定的理论补充和技术支持。本文主要介绍了纳米压痕技术的基本原理和样品制备,并从纳米压痕技术研究水泥基材料水化产物分相及微观力学特性、蠕变性能以及界面特性三个方面阐述了其在水泥基材料中的研究现状和相关成果,对目前研究中存在的问题进行了分析,并展望了其在水泥基材料研究中的发展趋势,以期为它更广泛深入地检测和研究水泥基材料微观性能提供参考。
As an important civil engineering material,cement-based material plays an important role in the national economic construction.At present,relevant researches on its mechanical properties mainly focus on the macroscopic mechanical properties such as compression and flexural resistance.In contrast,its micromechanical properties are relatively less studied.In view of the fact that the macroscopic mechanical properties of materials depended on the structural composition and mechanical properties at the microscopic level,it is one of the hotspots of current research to explore the performance mechanism of cement-based materials from the microscopic level.With the development of mechanical testing method of materials,nanoindentation technique has become the most advanced testing method for quantitatively characterizing the micro-mechanical properties of cement-based materials.On the other hand,the cement-based material is a heterogeneous material,and its hydration product contains a plurality of components.People are often subject to empirical constraints in phase division and quantitative analysis.Therefore,the performance of cement-based materials is far from to meet people’s demand.But the test data can be deconvoluted using the principle of maximum likelihood or least squares,thereby realizes the quantification of the compositions and dramatically improves the precision of the analysis.Nanoindentation technique can not only test the elastic modulus and hardness of the cement clinker(tricalcium silicate(C 3S),dicalcium silicate(C 2S),tricalcium aluminate(C 3A),etc.),but also test the micromechanical properties for the hydration product(hydrated calcium silicate gel(C-S-H),calcium hydroxide(CH),etc.)of cement-based materials and pores.By changing the loading system,especially the residence time of the load,the micro creep modulus can be measured in a short time and the macroscopic creep properties of the cement-based material can be quantitatively predicted.When combined with other microscopic testing methods(SEM,EDS,etc.),the latest chemo-mechanical technique can disclose the micro-mechanical properties of intimately intermixed phases and enable to distinguish chemical phases having strongly overlapping mechanical properties.So the phase can be accurately divided.By means of the change of the microstructure of the transition zone of the observation interface,it can provide certain theoretical supplement and technical support for the strength theory of the interface transition zone.This paper mainly introduces the basic principle of nanoindentation technique,sample preparation,and studies the phase-separation and micro-mechanical properties,creep properties and interface transition zone of cement-based materials from nanoindentation.Research status and rela-ted results are illustrated,and the problems existing on the current researches are analyzed,and the development trend in the research is prospected,in an effort to provide a reference to the extensive and in-depth study of the micro-performances of the cement-based material.
作者
盖海东
冯春花
董一娇
赵倩
李东旭
GE Haidong;FENG Chunhua;DONG Yijiao;ZHAO Qian;LI Dongxu(School of Materials Science and Engineering,Henan Polytechnic University,Jiaozuo 454000,China;College of Material Science and Engineering,Nanjing University of Technology,Nanjing 210009,China)
出处
《材料导报》
EI
CAS
CSCD
北大核心
2020年第7期107-114,共8页
Materials Reports
基金
国家自然科学基金青年基金项目(51502080,51872137)。
关键词
纳米压痕
水泥基材料
水化产物分相
微观力学特性
蠕变性能
界面特性
cement-based materials
nanoindentation
phase separation of hydration products
micromechanical properties
creep property
interfacial characteristic
