Title:
Mechanical Characterization of 3D Printed Ultra High-Performance Concrete
Author(s):
Shady Gomaa
Publication:
Web Session
Volume:
ws_F24_Gomaa.pdf
Issue:
Appears on pages(s):
Keywords:
DOI:
Date:
11/3/2024
Abstract:
As additive manufacturing of cementitious materials becomes more adopted, the need for accurate modelling and experimental validation grows. Currently there is a wide gap between material characterization for 3d-printable concrete and full-scale tests of printed structural elements. This work addresses this gap by proposing a novel technique to characterize the mechanical properties of 3d-printed ultra high-performance concrete (UHPC) and ultra high-performance fiber-reinforced concrete (UHPFRC) by accounting for geometric irregularities between printed layers which is overlooked by cast, polished, or cored specimen. A nano-modified 3d-printable UHPC mix is developed for this study, and early-age printability properties are validated using the manual flow table test. Hard-ened printed samples are tested under uniaxial compression, notched three-point bending, and split-tensile loading along their longitudinal, transverse, and normal directions. To allow representation of geometric irregularities along the layers and boundaries of the printed samples while maintaining smooth, parallel surfaces for load application, a highly flowable variation of the UHPC mix was used as capping material. Properties including compressive strength, tensile strength, and fracture energy are obtained and compared to cast specimen from the same concrete batch. The effect of fiber addition into these proper-ties is also studied. Additionally, results are validated computationally using the Lattice Discrete Particle Model (LDPM) to simulate the failure behavior at the heterogeneity scale. The printed samples are measured and scanned, and their exact form is used for the simulations to accurately match the model to the physical samples. The obtained results provide insight into the role of layer surface and shape in the strength of printed UHPC in comparison to cast specimen, while utilizing significantly less material than full-scale structural testing, in addition to providing important ca