Description
The use short fibers in mortars can address some issues for 3D printing technology, providing reinforcing and improving material sustainability. Among fibers, Sisal fiber (SF) is a good option for mortar reinforcement due to its natural origin, irregular cross-section and high flexibility. The aim of this study was to assess fresh and hardened properties modified by sisal fibers on 3D printable bio-based mortars for architectural applications. A 3D printable reference mortar with a 0-0.7 sand and a water to cement ratio of 0.45 was designed. The reference mortar was reinforced with 0.5, 1 and 1.5% volumetric fraction (VF) of 13 mm length SF and with 1% VF of a shorter SF of 6.5 mm length. Different rheological experimental tests were used to calculate initial yield stress and structural build-up of fresh mortars. Besides, several physical and mechanical properties were evaluated, comparing cast-in-mold and manually extruded samples. Finally, a printability study was carried out comparing a manual extruder and a 3D automatic printer robot. It was found that SF reduced initial consistency and slightly increased effective thixotropy over time. On the other hand, the length and amount of SF and the casting procedure showed differences in the physico-mechanical properties. Mortars with small SF amounts showed good printability while higher amounts were prone to clog the 3D printing pump system.
