Optimal Design of Mix Proportions for 3D Printed Concrete with Ferrochrome Slag and Aeolian Sand (2025-07)¶

The aim of this study is to optimize the mix design of 3D printed concrete mixed with ferrochrome slag and aeolian sand (3DPFAC). Through a one-way test, the influence laws of key materials such as mineral admixtures, water reducers, glue powder and fibers on the working properties (table jump fluidity, slump) and mechanical properties (flexural strength, compressive strength) of 3D printed concrete (3DPC) were investigated, and the optimal mixing ranges of each type of materials were determined. Revised Text:Following this, orthogonal tests were conducted for the four key influencing factors, namely, silica fume, superplasticizer, polyvinyl alcohol powder and polypropylene fiber, and their corresponding optimal dosing ranges to determine the influence levels of each factor. Finally, based on the results of the orthogonal analysis, the effects of each factor on table hopping flow, slump, flexural strength and compressive strength were investigated by using polar analysis of variance to arrive at the optimal combinations of material types and dosages: silica fume 7%, superplasticizer 0.6%, polyvinyl alcohol powder 1.2% and polypropylene fibers 0.2%. Experimental validation showed that the optimized material has excellent printability, uniform and smooth extrusion (zero nozzle clogging), smooth surface and low height deviation rate, which meets the requirements of printability and buildability. Microanalysis showed that 3DPFAC and Pouring specimens had a high degree of internal hydration, a dense matrix structure, and good synergistic effects of ferrochrome slag and aeolian sand aggregates, which did not negatively affect the material properties. However, compared with the Pouring specimens, 3DPFAC has more interfacial microcracks between layers, lower hydration degree, and obvious interfacial cracks between fibers and matrix, which leads to its destruction more easily under the external force, and this phenomenon is consistent with the results of the macro-mechanical properties test.