Title:
Microstructural Heterogeneity, Fracture, and Transport in Layered 3D-Printed Cementitious Materials
Author(s):
Shashank Gupta
Publication:
Web Session
Volume:
ws_S23_ShashankGupta1.pdf
Issue:
Appears on pages(s):
Keywords:
DOI:
Date:
4/2/2023
Abstract:
The layer-by-layer 3D-printing deposition process has demonstrated promising opportunities for enhanced mechanical properties by design. However, several fundamental questions remain about heterogeneities in the extrusion processes, solidification, and performance. This work investigates the processing-induced heterogeneities from the extrusion and resulting layered microstructure in two orthogonal directions (parallel and perpendicular to filaments) and aims to understand the fracture response and transport phenomena in rectilinear and architected cement paste materials. Using SEM and µ-CT, it was found that the processing-induced pore network includes weak directional interfaces between the filaments, in addition to the micro-channels in the direction along the filaments, which promoted the pore-crack interaction. The mechanical response was characterized using flexural tests and Weibull strength analysis alluded that the 3D-printing process dominates the crack initiation as controlled by the weak interfaces. A Brazil-nut test was proposed to effectively characterize the fracture response of rectilinear and architected materials in modes I and II. The results indicated that architecting the materials in helical arrangements promoted higher fracture toughness in mode I. Fluid transport was characterized by absorption using Neutron Radiography (NR), which indicated that the interfacial heterogeneities and their directionality dominate the water absorption and transport.