This study investigates the possibility of utilising bottom slag (BS) waste from landfills, and a carbonation process advantageous for the use of artificial aggregates (AAs) in printed three-dimensional (3D) concrete composites. In general, the main idea of granulated aggregates is to reduce the amount of CO2 emissions of printed 3D concrete objects (wall). AAs are made from construction materials, both granulated and carbonated. Granules are made from a combination of binder (ordinary Portland cement (OPC), hydrated lime, burnt shale ash (BSA)) and waste material (BS). BS is a waste material left over after the municipal waste burning process in cogeneration power plants. Whole printed 3D concrete composite manufacturing consists of: granulating artificial aggregate, aggregate hardening and sieving (adaptive granulometer), carbonation of AA, mixing 3D concrete, and 3D printing. The granulating and printing processes were analysed for hardening processes, strength results, workability parameters, and physical and mechanical properties. Printings with no granules (reference 3D printed concrete) were compared to 3D printed concretes with 25% and 50% of their natural aggregate replaced with carbonated AA. The results showed that, theoretically, the carbonation process could help to react approximately 126 kg/m3 CO2 from 1 m3 of granules.

This study focuses on the benefits of deploying plastic waste as a promising alternative to main 3D concrete printing (3DCP) binders. 3D printing technology improvements display that this construction method holds a significant potential by not only finding a globally greener way to developing 3D printing composites but also in researching a more sustainable approach to reducing carbon footprint on the planet, and also becoming one of the possibilities in replacing industrial wastes to ordinary Portland cement. As an alternative to ordinary Portland cement this paper analyses secondary raw materials like burnt shale ashes (BSA), plastic waste (PW) granules and grinded foam rubber (FR). These chosen materials help to solve two environmentally relevant problems: elimination of industrial waste and CO2 level reduction in concrete production, meantime enhancing the sustainability of the potential 3D printing concrete mixes that had been modified by wastes. Further review presents respective differences between fresh concrete and hardened mix properties. These experimental studies proved that one of four different mixtures significantly enhanced the stability of the studied parameters.