Mechanical properties of novel green high-strength fly ash concrete incorporating hemp fibers

Abstract

Cement production rose in the late 20th century. In response to environmental concerns, green concrete research and development have risen. The use of fly ash as a cement substitute in green concrete remains limited, despite global studies. This study aimed to investigate the feasibility and advantages of utilizing hemp fiber on the mechanical properties of high-strength green concrete (HSGC) containing different volumes of fly ash (FA). Hemp fibers were added at 0.5 % and 1 % of the total mixture volume, in combination with varying levels of FA (0, 10, 17.5, and 35 %) as a partial replacement material for the total volume of Ordinary Portland Cement (OPC) binder in the HSGC. Slump flow diameter and T50 slump flow were performed to assess the rheological properties of fresh concrete mixtures. The results show that even with a 35 % FA content, the flexural properties and ductility behavior of HSGC were significantly improved by the combined use of FA and hemp fiber at 28 days. The superior increase in compressive strength, splitting tensile strength, flexural strength, flexural toughness, and ductility was achieved with hemp-fiberized HSGC containing 17.5 % FA and 1 % hemp fiber by 22.3 %, 49.81 %, 14 %, 50.8 %, and 28 %, respectively, relative to the control mix. Thus, hemp fiber could extend fly ash use in HSGC production, reducing cement demand and energy consumption while improving concrete sustainability.