From Soil to Printed Structures (2023-10)¶

Three-dimensional (3D) printing of clayey soils has been gaining traction in construction and architecture due to its eco-friendliness and design advantages. However, no comprehensive method has yet been developed for transforming these soils into a mixture that facilitates both flowability and post-deposition stability. For the development of such a method, the rheological properties and performance of 12 mixtures of sand and clay were assessed using a rotational rheometer, a custom rigidity test, and pumping tests. Subsequently, linear correlations between various results were examined to identify meaningful statistical relationships. This was followed by an in situ cylinder printing test. An analytical model was used to predict the plastic collapse of the bottom layer. To better elucidate the failure mechanism, a digital image correlation of the in situ printing test was employed. Finally, the mechanical properties of the mixtures were assessed at 14 and 28 days. The results of this study indicate that values from flow-table tests and custom rigidity tests can be used to guide the design of soil-based mixtures for 3D printing. Rheological findings show that increased kaolinite content enhances the thixotropic effect of the mixture, while coarser particle distribution increases the static yield value. A cylinder printing test until breakdown suggests that a rotational rheometer test can predict element failure due to the bottom layer plastic collapse, based on the printing parameters. Disparities between the performance of fresh and hardened mixtures were revealed by the results of the mechanical tests.