Over the last decade, 3D-printing has become a real hype, with applications ranging from low end toys to high end machined parts. In the construction sector, its use would mean a move from traditional beams, plates or trusses to more organic or optimized shapes while maintaining strength and stiffness, and without need for scaffolding or formwork. Currently, 3D-printing of concrete is a technique in rapid development. Here, structural elements are fabricated by extruding a quick setting concrete mixture through a nozzle and stacking layers on top of each other. In fact, it resembles a 3D-printer for use at home, but on a massive scale. There are, however, 2 major differences. Firstly, the material is substantially different, and although it has been investigated in the recent past, we are convinced that more detailed research is necessary, especially into the evolution in mechanical properties and into temperature and shrinkage development during the printing process itself and thereafter. Secondly, and much more than in other printing applications, we need a reliable structural simulation model, that predicts the effects of the choices made during the printing process, e.g. the nozzle path or the printing speed, on the final properties. Moreover, we should be able to optimize these choices and create the best possible set for any given element, whether it be massive or rather slender. Within this research project we want to tackle each of the mentioned challenges.