3D concrete printing, material characterization, capacity prediction, and strength testing of a sub-scale concrete dome structure

This paper presents the results of printing, structural modeling and analysis, and testing a sub-scale geopolymer concrete dome structure as a preliminary step toward constructing a full-scale building. A broader objective of the study was to explore the potential of the printing method as an autonomous construction technique, including its possible use in space exploration as envisioned by NASA's 3D-Printed Habitat Challenge. The paper initially discusses a method developed for 3D printing (or additive manufacturing) of concrete, and then it presents the results of material characterization in the form of mechanical properties of printed concrete. This is then followed by developing a preliminary finite element modeling of a dome-shaped structure and estimating the failure mode and capacity under gravity loading. The prediction of the structural capacity of the dome was necessary prior to actual testing of the dome structure. Initial tests were carried out based on compressive strength and simple bending tests of printed geopolymer specimens. The test results were used in the finite element modeling to predict the failure load that can collapse the scale dome structure. The actual failure mode of the tested scaled dome structure under top-side loading was then compared with the predicted failure mode and capacity from the simulation. The observed discrepancies between the simulation and real-world test results highlight critical limitations in 3D concrete printing for complex shapes. The reduced structural performance revealed the shortcomings of conventional approaches in determining the structural behavior of printed components, emphasizing the need for more in-depth testing and research.