Highly ductile ultra-rapid-hardening mortar containing oxidized polyethylene fibers

• Published in: Construction & building materials Vol. 277; p. 122317
• Main Authors: Yoo, Doo-Yeol, Oh, Taekgeun, Chun, Booki
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 29.03.2021
• Subjects: Air-drying curing; Calcium sulfoaluminate cement; Oxidation; Polyethylene fiber; Strain-hardening characteristic; Ultra-rapid-hardening mortar; Strain-hardening characteristic; Oxidation; Polyethylene fiber; Ultra-rapid-hardening mortar; Calcium sulfoaluminate cement; Air-drying curing
• ISSN: 0950-0618; 1879-0526
• DOI: 10.1016/j.conbuildmat.2021.122317

•A robust strain-hardening ultra-rapid-hardening mortar (URHM) is developed.•Hydrates (C-S-H and ettringite) are abundantly formed after 4 h of hydration.•The surface of polyethylene fiber is oxidized by the plasma and chromic acid treatments.•Plasma treatment is more effective on improving tensile performance of URHM than chromic acid one.•Tensile specific energies of 124.8 and 381.1 kJ/m3 are achieved at 4 h and 28 d using plasma-treated fibers. This study aims to develop a strain-hardening ultra-rapid-hardening mortar (URHM). A mixture of calcium sulfoaluminate (CSA) cement, ordinary Portland cement (OPC), and gypsum was used to prepare the ultra-rapid hardening cement along with 2% (by volume) polyethylene (PE) fibers. The PE fibers were oxidized by plasma and chromic acid treatments to achieve a robust strain-hardening characteristic. Test results indicated that the tensile strain-hardening behavior of the URHM was achieved in only 4 h of air-drying curing and further improved through surface treatments. The compressive strength of the URHM with untreated PE fibers at 4 h and 28 d of air-drying curing was found to be 37.9 and 60.0 MPa, respectively, and it was slightly enhanced by using the treated PE fibers. Tensile strength and energy absorption capacity of about 5.1 MPa and 124.8 kJ/m3, respectively, were achieved for the URHM at an early age (4 h) using the plasma-treated PE fibers. The tensile performance of the URHM improved with the increase in the air-drying curing age and by using oxidized PE fibers. It was identified that the plasma treatments were more effective than the chromic acid treatment. Finally, the highest tensile strength and energy absorption capacity of approximately 9.95 MPa and 381.1 kJ/m3 were observed in the URHM containing oxygen-gas-treated PE fibers after 28 d of curing.