应变强化对水泥基复合材料抗冲磨性能影响研究

Effects of strain-hardening on anti-abrasion property of cementitious composites

摘要

如何从根本上大幅提升水泥基材料抗冲磨性能，是水电建设运维中的一项重要课题。基于轴拉应力-应变本构模型，重点研究纤维增强水泥基复合材料的拉伸应变行为与其主要力学性能及抗冲磨性能之间的关系。通过引入基于纳米偏高岭土的纤维粘结调节剂BA获得单因素改变的不同基体，分别测试2%纤维掺量(体积)下不同基体、同一基体不同纤维掺量下的拉伸行为及相应性能。结果显示，拉伸应变行为主要取决于纤维与基体之间的相互关系，并非简单依赖基体强度或纤维掺量；纤维粘结强度大于基体抗拉强度是实现应变强化的前提之一；应变强化不仅能使抗拉强度进一步增加，而且拉伸应变大幅提升，因而韧性显著改善，抗冲磨性能大幅提高。基于9%BA掺量的优化基体，纤维掺量1.5%和2.5%的拉伸行为分别为应变软化和应变强化，后者的控裂韧性是前者的43.7倍，抗冲磨强度是前者5.52倍，达到209.3 h·kg^-1·m²,是高性能C50硅粉抗冲磨混凝土的十倍以上。可见，应变强化是水泥基复合材料从脆性到韧性、从而实现抗冲磨性能突变的重要技术途径之一。

Abstract

How to remarkably improve anti-abrasion of cementitious materials is a big issue in hydropower construction and operation. So the relationship between axial-tension behaviors of fiber reinforced cementitious composites and its main mechanical properties including anti-abrasion was focused on research based on stress-strain constitutive model. Different matrices with univariate change ware prepared by fiber Bonding Adjustment(BA) based on nano MetaKaolin admixture. Tension characters and relative properties ware measured by both different matrices with 2% fiber and different fiber dosages in same matrix. The result showed that tension behaviors are mainly decided by the mutual function between the fiber and the matrix, not only simply depend on matrix strength or fiber dosage. One of the preconditions of strain-hardening is that fiber bonding strength should be higher than tensile strength of matrix. Strain-hardening not only let tensile strength to be increased further, but also enlarges tension strain significantly, which lead to improve toughness and anti-abrasion outstandingly. The tension behaviors of 1.5% and 2.5% fiber dosages based on optimized matrix with 9%BA are strain-softening and strain-hardening respectively, but the later toughness and anti-abrasion are 43.7 and 5.52 times of former, and its anti-abrasion strength reached 209.3 h/(kg/m²) which is ten times more than high performance C50-silica fume anti-abrasive concrete. It's indicated that strain-hardening is one of the key method to make cementitious composites achieve broken change of anti-abrasive property and being turned from fragility to tenacity.

关键词

应变强化 / 轴拉本构模型 / 抗冲磨强度 / 力学性能 / 韧性 / 纤维粘结强度

Key words

Strain-hardening / Axial-tension constitutive model / Anti-abrasion strength / Mechanical properties / Toughness / Fiber bonding strength

Author summay

董同亮(1975—), 男, 高级工程师, 技术部副部长, 学士, 主要从事水利水电工程建设、运营管理工作。E-mail: [e-mail]