Predicting Stabilized Soil Mixture Proportions for 3D Printing: Preliminary Study Using the Design of Experiments Approach

Abstract

The development of three-dimensional (3D)-printed earth construction frameworks is limited. From a materials science perspective, the mix proportioning of earth-based printable materials is a critical issue, primarily due to (1) the requirements in the fresh state, (2) the need for adequate stabilization, and (3) the variability of raw natural materials, which necessitates their characterization. This study aims to investigate stabilized soil for 3D printing. To achieve this, a central composite design (CCD) was followed in order to identify statistical models capable that can describe key properties of stabilized earth mixtures, namely, slump, Casagrande (CS), mass loss, and compressive strength, as functions of the following mixture input parameters: water-to-powder volume ratio (Vw/Vp), superplasticizer-to-powder weight ratio (Sp/p), and limestone filler-to-cement weight ratio (lf/c). Both potential printable and nonprintable stabilized earth mixtures were obtained, and Vw/Vp exhibited the main effect in all output properties evaluated. On the other hand, the mixture parameter lf/c did not influence the selected output properties. This is not surprising because the lf/c proportion in the earth composite is very small compared with the other powder materials (cement and soil). The superplasticizer had a significant impact on the fresh state, slump, and CS. A numerical optimization technique based on the desirability function was applied to the derived models to determine potential stabilized soil printable mixture ratios. Solutions were found for Vw/Vp ranging from 1.760 to1.852, while covering all Sp/p ranges of the CCD.