Expanded vermiculite acting as artificial flaws to enhance the tensile properties of high-strength engineered cementitious composites
Zhigang Zhang, Qiang Shen, Fengjiang Qin, Jamal A. Abdalla, Rami A. Hawileh, Yan Xiong
Abstract
In this study, an expanded vermiculite (EV) was proposed to substitute silica sand , and act as artificial flaws in high-strength engineered cementitious composites (ECC) to improve its ductility. Experimental and analytical investigations were conducted on the mechanical behavior , micromechanical analysis and microstructural analysis of ECC from macro-, meso-, and micro-scales. The results demonstrated that the inclusion of EV reduced the compressive strength of ECC composites from 77.6 MPa to 60.2 MPa, although this does not hinder its role as a constituent of high-strength concrete (60 MPa). However, compared with that of 2.56 % in reference ECC mixture, due to the EV addings, the strain capacity of ECC mixtures was increased up to 8.22 %. On the other hand, incorporating fine EV particles (0.15 mm, 0.42 mm, and 2 mm) was positive to the tensile strength of ECC mixtures with a 23 % improvement, while the addition of coarser EV (1–3 mm and 3–5 mm) led to an 8 % reduction. At microscale, the incorporation of EV reduced the critical flaw size and increased the flaw size , significantly increased the number of active flaws, as a result, more micro-cracks were initiated, and thus greatly improving ductility of ECC.