Experimental investigation of the improvements of rheological and physical properties in 3D concrete printing modified with biochar and steel slag

Abstract

Three-dimensional concrete printing (3DCP) has emerged as a revolutionary construction material technology, facilitating the incremental deposition of concrete layers for the construction of three-dimensional structures. This innovative technology is gaining widespread popularity due to its distinct advantages over traditional concrete methods, offering heightened design flexibility, fully automated mechanization, and the ability to efficiently construct intricate structures within a reduced timeframe, eliminating the need for manual labor. Contrary to the conventional concrete, assessing the flowability (the capacity of the concrete mixture to flow seamlessly and uniformly through the nozzle) and extrudability (the degree of ease with which the concrete can be pushed through or extruded from the nozzle.) of 3DCP becomes essential, as these properties are predominantly dictated by its rheological characteristics. Examining not only the compressive strength but also the buildability and open time is crucial when evaluating the mechanical characteristics of 3DCP. Compressive strength provides insight into the material's ability to withstand axial loads, while buildability and open time play essential roles in assessing construction feasibility and the temporal aspects of 3DCP This study aims to leverage biochar as a substitute material for cementitious components and steel slag as a partial replacement material for the fine aggregate component in 3DCP in improving the rheological and mechanical properties of 3DCP, while capitalizing on the sustainable attributes and economic advantages of these substitute materials.