Effectiveness of the rheometric methods to evaluate the build-up of cementitious mortars used for 3D printing

In this study, the effectiveness of different rheometric methods to evaluate the build-up of the cementitious mortars used for 3D printing was investigated. In the first step, 15 paste mixtures proportioned with various dosages of the nanoclay and the high-range water-reducer were made. The optimized paste mixture was then selected to produce 4 mortar mixtures with different quartz sand contents and gradations. The build-up of the mixtures was evaluated using a non-rheometric method, namely mini-slump cone, as well as the rheometric methods, including the static yield stress, and the storage modulus evolutions. Finally, the printing experiments were carried out using a custom-made 3D printer to evaluate the effectiveness of the investigated methods to assess the build-up of the mortars. The results indicated that different testing methods contributed in understanding different aspects of the build-up such as rigidification at rest or under shear. Each of these build-up aspects provided valuable information on the extrudability and the shape stability of the printed layers. (C) 2020 Elsevier Ltd. All rights reserved.