Experimental Study of Sustainable Engineered Cementitious Composites (ECC) Reinforced with Glass Fiber

Abstract

Fibers play a fundamental role in the performance of sustainable Engineered Cementitious Composites (ECC), which incorporates industrial by-products as partial cement replacements, as the characteristic high tensile strain capacity of ECC is achieved primarily through the crack-bridging effect of dispersed fibers. In the absence of fibers, this strain-hardening behavior cannot be realized. Among the available fiber types, glass fiber has gained considerable interest because of its high tensile strength and favorable compatibility with cement-based matrices. To get a deeper insight into the mechanical performance of ECC with glass fiber (G-ECC), this study experimentally examines the effect of fiber volume fraction on basic mechanical properties, including compressive and flexural strength capacities of G-ECC. Three mixtures containing 1%, 1.5%, and 2% glass fiber by volume were prepared and tested after 7 and 28 days of curing to obtain the compressive and flexural strengths. The test data showed that the compressive strength of G-ECC increased when the fiber content reached 1%, but declined as the volume fraction was further raised to 2%. This reduction at higher fiber contents is likely associated with fiber clustering and decreased matrix densification, which negatively affect material integrity. In contrast, flexural strength improved progressively with increasing fiber content up to 2%, reflecting enhanced crack-bridging efficiency and greater energy dissipation capacity. Furthermore, scanning electron microscopy (SEM) images of the microstructure of fibers, cementitious matrix, and the fiber–matrix interface across all mixtures were obtained. The microstructural observations provide additional insight into the mechanisms underlying the observed trends in mechanical performance.