Evaluation of the effect of rubber waste particles on the rheological and mechanical properties of cementitious materials for 3D printing

The use of 3D printing for cementitious materials is an increasingly viable option technically, economically, and environmentally for civil construction, generating a lower amount of waste. This work aims to evaluate the technical feasibility of using rubber as a fine aggregate in 3D printing mortars and its impact on its rheological and mechanical properties. Tests of compressive and flexural strength, flow-table, rheology and squeeze-flow were conducted to evaluate their fresh and hardened state properties. The total substitution of natural sand for rubber increased the rheological properties of dynamic yield stress (318–479.3 Pa), static yield stress (1604.1–1760.1 Pa) and plastic viscosity (4.15 Pa.s to 5.03 Pa.s). Lower compressive (19.9 MPa) and flexural (5.6 MPa) strengths were obtained for the mortar using rubber waste as aggregate. Also, the replacement of sand with rubber enhanced the anti-thixotropic behavior of 3D printing mortars. •Use of rubber as fine aggregate increased the dynamic and static yield stress.•Replacing sand with rubber increased the plastic viscosity of the 3D printing mortars.•Use rubber as fine aggregate decreased the mortars' strengths and consistency index.•The replacement of sand by rubber led to lower displacements in the squeeze-flow test.•Both aggregates produced 3DP mortars with good printability by rheological parameters.