Experimental study of mechanical and durability properties in hybrid binary and ternary fiber-reinforced ECC

Mahdi Kouhiazar Tulun¹Jafar Sobhani^2*Seyyed Mohammad Mirhosseini¹Ehsanollah Zeighami¹Mohammad Reza Basiri³

• ¹Department of Civil Engineering, Arak Branch, Islamic Azad University, Arak, Iran
• ²Department of Concrete Technology, Road, Housing & Urban Development Research Center (BHRC), Tehran, Iran
• ³Department of Textile Engineering, Arak Branch, Islamic Azad University, Arak, Iran

This research introduces an innovative approach to producing high-performance engineered cementitious composites (ECC) using hybrid fibers. By integrating steel, synthetic, and PVA fibers, the composites achieved a 40% increase in compressive strength, reaching 94.8 MPa at 28 days, alongside a 9.5% improvement in flexural strength, with the ternary mixture S20F10P2 showing the best performance. They also experienced a 31% increase in tensile strength, measuring 8.99 MPa for S10F20P2. The hybrid fibers further enhanced energy absorption, boosting flexural toughness by 20% (120 N.mm for S20F10P2) and promoting multiple microcracking behaviors, effectively limiting crack widths to around 60 micrometers. In durability tests, the ECC demonstrated excellent resistance to water penetration, with a depth of 3.5 mm for S10F0P2, mass loss of 4.4 gr/m² during freeze-thaw cycles for S0F0P0, and chloride ion ingress of 87 coulombs for the fiberless mixture. Additionally, incorporating ground granulated blast furnace slag (GGBFS) and silica fume as cement replacements improved mechanical performance and reduced CO₂ emissions by 338.2 kg/m³, highlighting the environmental benefits of these materials. The results demonstrated that incorporating hybrid binary and ternary fiber systems significantly enhanced ECC's compressive, tensile, and flexural performance and toughness while maintaining favorable durability characteristics. These findings indicate strong potential for utilizing the developed composite mixtures in industrial and public concrete overlay applications. The findings pave the way for eco-friendly construction practices and advancements in sustainable concrete technology.