INTERFACIAL BEHAVIOUR OF 3D PRINTED CONCRETE: FRESH AND HARDENED STAGE

Ediae, Joseph Osamwonyi

Abstract

The construction industry faces significant challenges in meeting the demands of a growing population and urbanisation, which are compounded by environmental sustainability concerns and low productivity. The 3D Printing Concrete (3DPC) technology can address these challenges by overcoming issues related to skilled labour, resource depletion, site safety, and environmental impact, which are prevalent in conventional construction techniques. This innovation offers enhanced geometric freedom and functionality at minimal additional cost, eliminating the need for formwork, and reducing labour through additive manufacturing.

However, the acceptance of the 3D Printing Concrete (3DPC) introduces complexities, especially with regard to the stability of fresh concrete during the printing process and the proper stacking of printed layers to avoid failure in its hardened material state. The purpose of the study is to address these challenges by focusing on material formulation, the optimisation of the printing process, and computational analysis.

To expand the understanding, the investigation focused on 3D extrusion-based concrete printing of unreinforced and basalt fibre-reinforced concrete. Two critical failure mechanisms in fresh-state concrete, such as elastic buckling and plastic collapse, are identified and evaluated using numerical Finite Element Models (FEM). The FEM models incorporate transient material properties obtained from early-age concrete experimental testing, revealing thixotropic effects and changes in failure behaviour as the concrete ages.

In addition, the study emphasises the importance of the triaxial compression test in defining input parameters in numerical modelling. The study demonstrates the effectiveness of numerical models in controlling fresh concrete structural behaviour and facilitating the optimisation of improved geometrical structures. In hardened concrete, the bond strength between layers is recognised as a critical factor influencing the structural behaviour of 3D printed elements. An extensive experimental package is conducted to explore the impact of various process parameters on the bonding strength of 3D printed concrete.

The integration of experimental and numerical models enhances the understanding of 3D-printed concrete, particularly its hydration during early hardening and its mechanical strength once hardened. This advancement supports the wider adoption of 3D-printed concrete as a standard practice in construction.

• Thesis Type: Thesis
• Online Publication Date: May 29, 2025
• Deposit Date: May 19, 2025
• Publicly Available Date: May 30, 2027
• Award Date: May 19, 2025