NDT to characterize 3D printed concrete interlayer bonds

Helsel, Michelle Annette

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https://hdl.handle.net/2142/105090 Copy

Description

Title

NDT to characterize 3D printed concrete interlayer bonds

Author(s)

Helsel, Michelle Annette

Issue Date

2019-04-25

Director of Research (if dissertation) or Advisor (if thesis)

Popovics, John S.

Department of Study

Civil & Environmental Eng

Discipline

Civil Engineering

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

M.S.

Degree Level

Thesis

Keyword(s)

• 3D printed concrete
• interlayer bonds
• bond condition
• characterization
• NDT
• non-destructive testing
• non-destructive evaluation
• additive manufacturing

Abstract

3D printing in the construction industry involves extruding layer upon layer of concrete to create a desired structure. Layer interfaces can form cold joints, or bond weaknesses, that could compromise structural integrity. Furthermore, the unique characteristics and geometric constraints associated with 3D printed concrete render traditional inspection methods to characterize material quality useless. This research examines nondestructive testing (NDT) techniques that characterize the interlayer bond quality (bond strength) of 3D printed concrete in situ. An experimental study applied four NDT methods (x-ray radiography, ultrasonic pulse velocity (UPV), vibration resonance, and multi-element array ultrasonics) to idealized, layered concrete specimens that simulate layers of a 3D printed structure. The bond interfaces in the samples were characterized into well bonded, weakly bonded, and disbonded categories based on mechanical tests applied to the samples to measure bond strength. Two of those NDT methods, x-ray radiography and multi-element array ultrasonics, showed promise in characterizing bond strength, and threshold values for data from both methods were established to characterize interlayer bonds into one of the three defined bond quality categories. Multi-element array ultrasonics and UPV were then adapted and applied to full-scale 3D printed concrete walls. UPV was not sensitive to the bond condition. However, multi-element array ultrasonics successfully located and categorized cracks, expansion joints, and layer debonding on the full-scale 3D printed structures.

Graduation Semester

2019-05

Type of Resource

text

Permalink

http://hdl.handle.net/2142/105090

Copyright and License Information

Copyright 2019 Michelle Annette Helsel

Owning Collections