Development of composites for 3D printing with reduced cement consumption

Recently, 3D concrete printing (3DCP) based on additive manufacturing techniques has been gaining prominence in the construction industry. However, in order to meet the extrusion requirements, 3DCP mixtures are usually dosed with high Portland cement contents. Thus, a promising solution to make this technology more sustainable is the reduction of cement consumption through partial replacement by supplementary cementitious materials (SCM). In view of this, this paper aims to develop composites for 3D printing containing different percentages of limestone filler and metakaolin as binder fraction of the analysis compositions. The proposed mixtures encompass replacement contents of 30% (using only limestone filler) and 40% (one with 40% limestone filler and, another, containing 30% filler and 10% metakaolin). In the fresh state, these mixtures were evaluated through the tests of spread, slump, bulk density, incorporated air content, squeeze-flow and buildability. In the hardened state, flexural strength, compressive strength, interlayer adhesion strength, specific gravity, void index and water absorption by immersion were analyzed. The results show the possibility of obtaining printable composites with reduced cement consumption for the printing system used, establishing itself as a relevant alternative for 3DCP technology in accordance with the criteria required for the printing system.