Study of 3D printed concrete with low-carbon cementitious materials based on its rheological properties and mechanical performances

Using high-volume cement in 3D printed concrete (3DPC) can lead to later crack formation. Accordingly, mineral admixtures can be used as cement replacements to mitigate this disadvantage. In this study, fly ash, slag, and a type of silica fume (with a high water consumption) are selected as supplementary materials in 3DPC under different substitution rates. A method for the printability evaluation of each test group in the orthogonal experiment is proposed based on a comprehensive analysis of the rheological behavior and mechanical performance of the test samples. The results indicate that a cement replacement ratio of 50% can be achieved in 3DPC while retaining its rheological behavior and mechanical performance. According to the actual printing test, the selected silica fume improves the buildability of 3DPC and can serve as an economical and effective cement substitute. The findings in this study also reveal the potential application of poor-quality mineral admixtures in 3DPC, which can increase economy and reduce CO2 emissions.