高韧性低收缩纤维增强水泥基复合材料特性及应用

Characteristics of high ductility and low shrinkage engineered cementitious composite and its applications

基于细观力学设计的高韧性纤维增强水泥基复合材料(Engineered Cementitious Composite-ECC)是当前比较成功的具有应变硬化特性的水泥基材料。本文介绍了近期通过改进传统ECC基材,研制的低收缩ECC材料的主要力学特性,包括干燥性能,单轴拉伸与压缩性能,弹性模量及极限拉压应变等主要力学参数。试验结果显示,采用低收缩基材的ECC的28d干燥收缩值分别为传统ECC干燥收缩值的0.12～0.20。单轴拉伸结果表明,采用低收缩基材的ECC的极限应变、裂纹宽度等参数与传统ECC相比,也有了明显的改进。在0.55～0.25范围内调整水胶比可以制备出抗压强度为20～60MPa,并保持应变硬化和多点开裂特性不变的水泥基复合材料。除拉伸时表现出显著的塑性变形外,在抗压试验中,该材料在压应力峰值过后也同样表现出明显的类似于金属材料屈服的塑性变形特性。最后对该材料近期应用研究作了介绍。

Micro-mechanically designed engineered cementitious composite （ECC） is one of the successful materials for ductility improvement of the cement based materials. This paper reports the mechanical properties of a new class of engineered cementitious composite recently developed with characteristic of low drying shrinkage. Experimental results show that drying shrinkage of the composite is greatly reduced as using the low shrinkage cementitious material in matrix, while the composite remains strain-hardening and multiple cracking characteristics. The measured drying shrinkage strain in 28 days is only 0.12 to 0.20 of shrinkage of the traditional ECC. The average tensile strain capacity after 28 days curing can achieve 2.5% of the low shrinkage ECC with tensile strength of 4-5MPa. The experimental results also show that the composite with compressive strength ranging from 20 to 60MPa can be obtained by varying w/c from 0.55 to 0.25, while remaining the tensile strain hardening and multiple cracking performances. A significant plasticity, like yielding of metal, is found under compressive load after peak stress. Finally, recent application studies are introduced.