Title:
The Use of Steel Fiber Concrete in Combination with Post Tensioning
Author(s):
Hendrik Thooft
Publication:
Web Session
Volume:
ws_S23_HendrikThooft.pdf
Issue:
Appears on pages(s):
Keywords:
DOI:
Date:
4/2/2023
Abstract:
Conventional approaches to concrete 3D printing relies on printing concrete in a straight (linear) print path, with layers overlaid on top of each other. This results in inter-layer and inter-filament joints being potential weak spots that compromise the mechanical performance. This paper evaluates simple alterations to the print geometry to mitigate some of these effects. A printable mixture with 30% of limestone powder replacing cement (by mass), with a 28-day compressive strength of about 70 MPa in the strongest direction, is used. S- and 3-shaped print paths are evaluated as alternatives to the linear print path. Staggering of the layers ensures that the inter-filament joints do not lie on the same plane along the depth. Flexural strength enhancement is observed when print geometries are changed and/or layers are staggered. Flexural and fracture properties indicate that smaller layer heights are beneficial for unreinforced and fiber-reinforced 3D printed mortars, even though this results in greater number of interfaces and longer printing times. A small amount of steel fiber reinforcement is shown to be useful in eliminating the negative effects of weak interfaces on the measured bulk properties. The study shows that print geometry modifications mitigate mechanical property reductions attributed to inter-filament defects in concrete 3D printing.