Influence of an extrusion approach on the fiber orientation and mechanical properties of engineering cementitious composite

Abstract

In this study, an extrusion approach was proposed to improve the fiber orientation degree in engineering cementitious composite (ECC) during the casting process. The influence of the casting approach on the fiber orientation and mechanical behavior was investigated. Specimens were prepared by two different casting approaches: the extrusion and the commonly adopted one. The fiber orientation was detected using scanning electron microscopy (SEM) and image processing techniques. Four-point bending test together with the digital image correlation (DIC) technique was conducted to characterize the bending behavior of the prepared specimen. The results showed that the proposed extrusion approach can significantly improve the fiber alignment in the matrix. The fiber orientation factor (α) of the extrusion approach made EX-ECC specimens is approximately 28% higher than the conventional approach made C-ECC specimens. The ultimate flexural strength of the EX-ECC specimens is 46% greater than the C-ECC specimens. In addition, the maximum mid-span deflection of the EX-ECC and C-ECC specimens were 36 mm and 28 mm, respectively. It was also found the fiber alignment can contribute to restricting the crack width growth. The major crack width of EX-ECC specimens was much smaller than C-ECC specimens when flexural stress was below 11.6 MPa. The study confirms that the proposed extrusion approach achieved a higher degree of fiber alignment.