Sisal fiber reinforced mortar for 3D printing applications in construction

摘要

The use short fibers in mortars can address some issues for 3D printing (3DP) 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 of sisal fibers on 3D printable bio-based mortars for architectural applications. A 3D printable reference mortar with a 0-0.6 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. An experimental evaluation of 3DP mortars comprising several rheological parameters at fresh state and physical and mechanical properties in hardened state was carried out to assess mortars’ extrudability, printability and hardened performance. Printability was also evaluated by trials using a manual extruder and a robotic 3D printer. It was found that SF reduced mortar consistency initially and over time, modifying effective thixotropy. On the other hand, the length and amount of SF and the casting procedure showed differences on the physical and mechanical properties. Mortars with small SF amounts showed good printability while higher amounts were prone to clog the 3DP pumping system.