Mechanical properties of 3D printed concrete in hot temperatures

Concrete 3D printing is continuously studied as a new construction method. However, the use of concrete for this application is challenging in terms of workability and mechanical performance. Additionally, this technology is still lacking evaluation standards and guidelines. Furthermore, performance of printing concrete in hot temperature conditions is still generic. This study was conducted to assess the mechanical properties of a 3D printed fiber-reinforced concrete mix in two environmental conditions: ambient and hot. Compressive, flexural, and interlayer bond shear strengths were evaluated. A novel test setup was designed for bond strength evaluation at different printing time intervals. Compressive strength was evaluated to be 47 MPa in control cubes. Results from compression and bond tests indicated accelerated water evaporation and surface dehydration in hot conditions, and that the presence of joints in printed parts is detrimental to such parameters. Flexural strength was increased in hot temperatures compared to control and ambient specimens by 21% and 18% respectively. Flexural strength results demonstrated that fibers have a good orientation by the print process, and can be further improved in hot conditions due to lower material viscosities. (C) 2020 Elsevier Ltd. All rights reserved.