Microstructure and mechanical properties of hardened cement paste including Nylon 66 nanofibers

•Nylon 66 nanofibers with rough surface were fabricated.•A methodology to mix cement pastes with the nanofibers was proposed.•The bridging effect of nanofibers in the hardened cement pastes was examined.•Strength & toughness of hardened cement pastes with the nanofibers were improved. The objective of this study is to investigate the microstructure and the mechanical properties of hardened cement paste including Nylon 66 nanofibers (NFs). Nylon 66 nanofibers are fabricated and mixed with ordinary Portland cement through an electrospinning process. With the desire of fabricating the rough surface nanofibers, two volatile agents as chloroform and dichloromethane are respectively introduced into the formic acid for dispersing Nylon 66 pellets. Scanning electron microscope (SEM) and thermogravimetric analysis (TGA) techniques are employed to investigate the bridging effect of nanofibers among cement hydration products as well as the proportion of nanofibers in the hardened cement pastes. The observations from mechanical strength experiments show the feasibility of Nylon 66 nanofibers in enhancing cementitious material, i.e., increase up to 30% in tensile strength, 8% in compressive strength and 49% in toughness when introducing Nylon 66 nanofibers into the hardened cement pastes.