Fresh and Mechanical Properties of Low-Cement Mortars for 3D Printing (2022-04)¶

The trend of concrete science is aimed at reducing the consumption of cement and the use of 3D printing technologies. Based on non-traditional technical silica, 3D printed mortars were designed with a saving of 70% of cement. The binder components were studied by X-ray spectral microanalysis, diffraction granulometric analysis, while the finished mixtures were tested for freshness and mechanical properties. It was established that the PFM-NLK additive at a concentration of 0.7% is characterized by the greatest plasticizing effect; in this case, the maximum slump flow is reached 179 mm. The presence of a larger number of particles with a size of 3 to 12 µm in the developed binders of low water demand provides a more complete interaction of cement particles with water during hydration, significantly reducing the number of non-hydrated grains in the binder. The setting time and rheological parameters of the developed cement pastes make them suitable for 3D printed mortars. The mechanical properties of low-cement mortars indicate their high strength in bending and compression. The compressive and flexural strength of the developed mortars at the age of 28 days reached 62.9 MPa and 7.9 MPa, which is better than the control cement CEM I 42.5 N by 23% and 52%, respectively.