高韧性纤维混凝土单轴受压性能及尺寸效应

Mechanical Performance and Size Effect of Engineered Cementitious Composite(ECC)Subjected to Uniaxial Compression

高韧性纤维混凝土(ECC)具有优异的韧性、卓越的耗散能力及裂缝无害化分布的特点,能够明显改善结构的抗震性能与耐久性。通过对三种不同高厚比的立方体与棱柱体共60个试件进行单轴受压试验,探究高韧性纤维混凝土的受压性能、变形机制及尺寸效应对试件力学性能的影响,测得了不同高厚比试件受压的应力-应变全曲线。结果表明:高韧性纤维混凝土在裂缝发展及破坏模式上与普通混凝土存在明显的区别,由于纤维的桥接作用,在加载过程中材料表现出较强的压缩韧性,试件破坏以后仍保持相对完整,极限压应变约为普通混凝土的10倍;当高厚比大于1时,材料抗压强度对尺寸的敏感性降低;峰值应变与抗压韧性系数随着高厚比的增加逐步减少。结合电镜扫描结果,对高韧性纤维混凝土中纤维的分布、桥接情况及纤维增韧增强机制进行了分析与讨论。

Engineered cementitious composite(ECC)has excellent toughness,dissipation capacity and distribution of multiple cracking,application of ECC can improve seismic ability of structure.The compressive properties,deformation mechanism and size effect of ECC were studied based on the uniaxial compression test of 60 specimens with three different height-thickness ratio.Accor-ding to the test results,the axial compressive stress-strain curves and performance rule of different specimens were obtained.Engineered cementitious composite showed good compressive resilience in the compression failure,which was markedly different from ordinary concrete.The destruction of ECC specimens remains relatively complete and the ultimate strain was 10 times higher than concrete.Different from ordinary concrete prism test results,the ratio of height to thickness had little effect on the strength of ECC prism.However,the height-thickness ratio has a great influence on the peak strain and toughness index of ECC prism.Furthermore,the microstructure of ECC with high toughness was observed through scanning electron microscope,and fiber distribution,bridge connection situation and fiber reinforcement mechanism of ECC were analyzed.