Overburden Materials from the Iron Mining as Raw Materials for AAM: Preliminary Assessment of Mixes for 3D Concrete Printing

3-D concrete printing (3DCP) is perceived as an important technology for the future of civil engineering; it may accelerate the construction process, reduce labor costs, and potentially generate significantly less waste materials. However, 3DCP still presents many challenges, such as the uncertainty on the construction costs and the employment of carbon intense materials such as Portland cement (PC). The employment of wastes from the mining activities is one alternative to reduce the costs and improve the sustainability of 3DCP mixes. Such wastes are usually too fine to be employed as concrete raw materials but are suitable in terms of particle distribution for C3DP mortars. This paper studied the activation of an alkali-activated overburden material (OM) from the iron mining industry as binder for 3DCP mixes. A ground granulated blast-furnace slag (GGBFS) was used as main binder to improve the mechanical properties. A fine quartz mining tailing was also employed as single aggregate. The mixes were compared with a reference commercial PC mortar developed for 3DCP. The preliminary assessment comprised of fresh properties (consistency), extrudability and compressive strength evaluation. A visual observation determined the susceptibility to shrinkage and cracking of extruded mixes. The results shows that mining wastes may be important low-carbon materials in the development of 3DCP.