Printability and Mechanical Properties of 3D Printing Ultra-High-Performance Concrete Incorporating Limestone-Powder (2024-04)¶

The superior mechanical properties of ultra-high performance concrete (UHPC) offer the possibility of eliminating steel reinforcement in 3D printed structures. As a kind of by-product of the limestone quarry, limestone powder (LP) can contribute to diminishing the carbon footprint and cost of 3D printing UHPC (3DP-UHPC). This study systematically investigates the effect of LP with different contents and fineness on the rheological properties, printability and mechanical properties of 3DP-UHPC. The incorporation of LP results in the decline in the static and dynamic yield stress of UHPC, which can improve the extrudability of 3DP-UHPC, but it concurrently results in a reduction in the buildability. Reducing the fineness of LP helps to improve the buildability of 3DP-UHPC. The increase in LP content enhances the flexural and compressive properties of 3DP-UHPC, mainly related to the improved compactness of particles and decrease of porosity. However, an excessive content of LP causes significant reduction in mechanical properties due to the relatively poor printability of 3DP-UHPC. In this study, 3DP-UHPC with 10 % LP exhibits the highest flexural strength and compressive strength, reaching 37.1 MPa and 153.1 MPa, respectively. This study may provide guidance for the development and utilizing of environmentally friendly 3DP-UHPC.