An experimental study on the influence of waste rubber particles on the compressive, flexural and impact properties of 3D printable sustainable cementitious composites

Abstract

To promote the sustainable development of the construction industry, this study examined the influence of the rubber particles addition on the fresh and hardened engineering properties of rubber particle (RP) modified 3D printable sustainable cementitious composites (3DPSCC) incorporating polypropylene (PP) fibers, in which RP derived from waste tires partially replaced sand between 0% and 100% volume replacement. A series of flowability tests, printing tests and mechanical tests in different loading directions were carried out to investigate the printability and anisotropic mechanical properties of the 3DPSCC. The results show that all test specimens can be successfully printed due to their good workability, extrudability, and buildability in the fresh state. The compressive, flexural strength, and impact strengths of 3DPSCC, in general, decreased with the increasing RP content and exhibited obvious anisotropy, which could be owing to the presence of both inter-layer and intra-layer interfaces in each group of specimens during the printing process. The impact resistant of the modified specimens improved with the addition of RP, as the average maximum displacement gradually increased from 0.41 mm to 0.92 mm, despite the weakening strength. The optimal mixture was regarded as RP-40 (40% RP replacement) exhibiting comparable anisotropic compressive strength (higher than 30 MPa), enough anisotropic flexural strength (higher than 4 MPa), and superior energy dissipation capacity (highest among all 3DPSCC), which can meet the strength requirement of concrete (i.e., 25 MPa for steel reinforced concrete structure) and is suitable for structural applications as a sustainable impact-resistant material.

Keywords

• 3D concrete printing
• Rubber particles
• Anisotropic mechanical properties
• Impact behavior
• Microstructure