Effect of Metallic Fibers on the Print Quality and Strength of 3D Printed Concrete (2020-07)¶

3D concrete printing is a promising technology in the construction field. Un-availability of standards/specifications related to certification of 3D printed structures and lack of reinforcement in printed concrete are the major factors behind the under-utilization of such innovative technology. Addition of fibers as reinforcement in the printable mix could be considered as viable solution to improve mechanical properties of printable mix particularly tensile strength. In this regard, recently carried out studies have used mostly non-metallic fibers with low modulus of elasticity and tensile strength. In this study, effect of adding flexible amorphous metallic fibers on the print quality and mechanical properties (flexural and direct tensile strengths) of resulting mixes has been investigated. Fibrous and non-fibrous mixes were designed. To prepare fibrous mixes, metallic fibers were used at dosage of 20 kg/m3, 30 kg/m3 and 40 kg/m3. Further, to study the influence of fiber length on the print quality and strength, fibers of length 5 mm, 10 mm and 15 mm were used. Reference specimens for tensile and flexural strength tests were also cast in molds using all mixes used for printing. Results showed that addition of metallic fibers of length 10 mm and 15 mm exhibited detrimental effects on the print quality, however, strength values, particularly tensile strength of printed concrete were observed to be enhanced by the addition of these fibers. Although print quality of mix containing fibers of 5 mm length was least affected, no positive impact of these fibers on the mechanical strength of printed concrete was noticed.