RESEARCH ARTICLE


Structural Behavior of Layer-Printed Reinforced Concrete Beams



Ghassan K. Al-Chaar*, Peter B. Stynoski, Marion L. Banko
U.S. Army Corps of Engineers, Engineer Research Development Center, Construction Engineering Research Laboratory, Champaign IL 61822, USA


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Creative Commons License
© 2018 Al-Chaar et al

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: https://creativecommons.org/licenses/by/4.0/legalcode. This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

* Address Correspondence to this author at the U.S. Army Corps of Engineers, Engineer Research Development Center, Construction Engineering Research Laboratory, Champaign, IL 61822, USA; Tel: 217-373-7247; E-mail: ghassan.k.al-chaar@usace.army.mil.


Abstract

Three-dimensional printing with atypical paste and mortar mixtures has been a topic of research and demonstration within the commercial and military sectors for several years. However, to the authors’ knowledge, printing with traditional concrete (a mixture of cement, fine- and coarse aggregate, and gravel) has yet to be investigated at the scale of habitation structures. This article explores the concrete material properties, printing process, and flexural testing of three-dimensionally printed concrete beams.

Objective:

The study aims to perform bending tests of nine normal strength, additively manufactured concrete beams when reinforced with various combinations and types of meshes and bars, and determine the flexural capacity of each reinforcement combination and type.

Methods:

The structural behavior of each layer-printed beam was evaluated in third-point loading to failure. All beams were printed to mimic a simply supported, flat roof beam spanning 4.57 m, incorporating seven varied reinforcement schemes.

Results:

Results show a layer-printed concrete beam with infill webbing that commonly fails in the shear span due to weak nodal connections. Test results also indicate that, in layered beam configurations, the interface between concrete and reinforcement significantly influences overall beam performance.

Conclusion:

Test results indicate that the interaction between concrete and reinforcement in layer-printed beams did not adequately bond for optimal beam performance. Further testing and variation the size, placement, roughness of beam reinforcement and thickness of concrete layers are needed to fully characterize the effect each reinforcement scheme has on flexural capacity and ductility

Keywords: Additive manufacturing, Bending, Failure modes, Flexural strength, Layered, Normal strength concrete, Three-dimensional (3D) printing.