Decarbonized 3D printed concrete incorporating lithium slag and PVA fiber: buildability, mechanical, and microstructural insights

The 3D concrete printing technology is ubiquitously enhancing modern construction, while its’ production generates high carbon footprint due to high cement content in the mix. The use of low–carbon pozzolans in 3D concrete printing reduces cement usage, however low–volume incorporation of these pozzolans insignificantly offset the carbon footprint. This study pioneers the use of 40% lithium slag (LS) as a cement replacement in the production of decarbonized 3D printed concrete and assesses the changes in rheology, buildability, mechanical, and microstructural properties with/without 1% polyvinyl alcohol (PVA) fibre. The 40% LS mix enhanced 13% higher plastic viscosity recovery compared to the control, and the corresponding buildability height was increased by 34% in the same comparison. At 28 days, the control and 40% LS specimens gained 34.2 MPa and 32.1 MPa of compressive strength. The flexural and bond strengths of 40% LS mix were 3.90 MPa and 2.23 MPa at 28 days. PVA (1 vol.%) fibres incorporated 40% LS mix enhanced the printing quality by reducing the filament breaking, which gained 4.60 MPa and 2.52 MPa of flexural and bond strengths at 28 days. Microstructural analysis using BSE-EDS indicated the formation of amorphous and amorphous intermediate hydration products in contributing mechanical strength development of LS-based 3D-printed concretes. PVA fibre incorporated 40% LS mix reduces 31% embodied carbon compared to the control and establishes its potential to decarbonize and enhance the performance of 3D-printed concretes.