3D printed concrete: multiscale mechanical characterization and computational modeling

Bayrak, Alper Tunga
This thesis presents a comprehensive exploration of the physical, mechanical, and thermal properties of 3D Printed Concrete (3DPC) structures across micro, meso, and macrostructural scales. The central focus is the analysis of full-scale walls under rigorous mechanical tests, revealing a notable and novel discovery: the mechanical properties —compressive strength, elastic modulus, and tensile strength— of the lower part of the 3DPC walls enhanced by up to 108%, 53%, and 100%, respectively, compared to the upper parts. This novel and dominant elevation effect on mechanical properties surpasses the previously known anisotropic behavior in 3DPC. The investigation extends to material modeling, introducing the Continuum Damage Plasticity Model (CDPM) for cyclic loading of concrete. The numerical implementation using the Backward-Euler method is meticulously examined. Micro and meso scales are scrutinized using computed tomograms (CT), shedding light on anisotropic behavior due to porosity and interlayer effects through finite element methods by using CDPM and traction-separation laws. The macrostructural assessment involves subjecting 3DPC walls to lateral loads up to failure for earthquake performance. Digital image correlation method is used to evaluate displacement counters and fracture behavior of these walls. The contributions of individual components, including truss and web elements, are thoroughly examined using finite element simulations. This thesis not only expands the understanding of the anisotropic behavior of 3DPC but reveals a novel and more dominant elevation effect on mechanical properties. These findings contribute significantly to existing knowledge and bear important implications for future research and practical applications in the realm of 3DPC.
Citation Formats
A. T. Bayrak, “3D printed concrete: multiscale mechanical characterization and computational modeling,” M.S. - Master of Science, Middle East Technical University, 2024.