Three-dimensional concrete printing (3DCP) has become recognized as a possible alternative to conventional concrete construction, mainly due to its potential to increase productivity and reduce the environmental impact of the construction industry. Despite its up-and-coming popularity within the field, limited research has quantitively investigated the environmental benefits that 3DCP brings. This paper investigates the environmental tradeoff of utilizing 3DCP over conventional construction by conducting a detailed cradle-to-gate life cycle assessment (LCA) study of four case-scenarios (conventional concrete construction, 3DCP with reinforcement elements, 3DCP without any reinforcement, and 3DCP without any reinforcement and utilizing a lightweight printable concrete material.) These case-scenarios were carefully selected to quantify the environmental impact of 3DCP while emphasizing the importance of the material composition. The LCA was conducted for a 1 m² external load-bearing wall in all four scenarios. The LCA analysis showed that 3DCP significantly reduced environmental effects in terms of global warming potential (GWP), acidification potential (AP), eutrophication potential (EP), smog formation potential (SFP), and fossil fuel depletion (FFD), as compared to conventional construction methods. However, these environmental improvements diminished when 3DCP was coupled with the use of conventional reinforcement elements. Moreover, the use of an alternative concrete mixture in 3DCP showed a further decrease in the GWP, AP, EP, and FFD impact. Ultimately, the findings in this paper support the advantages of 3DCP technology and recommend the investigation of the development of (i) sustainable printable concrete materials and (ii) novel reinforcement techniques that are suitable for 3DCP rather than adopting conventional reinforcement techniques.

The aim of this experimental study is to develop high strength and lightweight concrete mixture suitable for structural applications. This work investigates the effect of replacing normal aggregate either partially or totally with expanded perlite aggregate. This material allows for better thermal insulation properties, thus decreasing the energy usage within the life cycle of the concrete structure. Expanded perlite aggregate was used in concrete by 20%, 40%, 60%, 80%, and 100% in replacement of the natural aggregate. Material characterization tests of compressive strength, flexural strength, and thermal conductivity were carried out for six concrete mixtures. In addition, microstructure analysis was performed with the aid of a micro-computed tomography system to investigate the effects and relation of microstructure quantities on material properties. The proposed concrete mixture, which has 100% of expanded perlite aggregate, has a unit weight of 1703 kg/m³ and achieved reduction percentage of thermal conductivity around 62% (1.81 to 0.69 W·m⁻¹·K⁻¹) and a compressive strength of 42 MPa at 28 days; and thus is ideal for structural applications with enhanced properties.