Title:
Examining Influence of the Printing Directionality on the Freeze-Thaw Response of 3D-Printed Cement Paste
Author(s):
Rita Ghantous
Publication:
Web Session
Volume:
ws_S23_RitaGhantous.pdf
Issue:
Appears on pages(s):
Keywords:
DOI:
Date:
4/2/2023
Abstract:
The use of 3D printing with cementitious materials is increasing in the construction industry. However, there is limited information on the freeze and thaw (FT) response. While few studies have used standard FT testing procedures (ASTM C666) to assess the FT response, this approach is insensitive for examination of anisotropy due to printing directionality. This paper investigates the FT response of 3D-printed cement paste elements using thermomechanical analysis (TMA). The critical degree of saturation (DOSCR) was determined. Micro-computed tomography (micro-CT) was conducted to quantitatively understand potential heterogeneities in the pore microstructure of 3D-printed material. The DOSCR is independent of the printing directionality and was comparable to conventionally cast specimens. FT damage was greater in printed samples as compared to cast samples (@ DOS = 100%). The use of a low w/c in 3D printed materials, which is preferred for buildability purposes, led to low capillary porosity, which thus decreased the amount of freezable pore solution, and increased the FT resistance. Micro-CT analysis demonstrated a significant 4.6 times higher average interfacial porosity in the interfacial regions compared to the filament cores, supporting the significant heterogeneity in the bulk layered microstructure of 3D-printed cement paste materials.