Cementitious mortars and polyurethane foams for additive building manufacturing

The use of additive manufacturing in the construction industry is still in a state of infancy. Research into suitable materials for Additive Building Manufacturing ABM) have centred upon polymeric and cementitious materials, with the trade-off between workability and buildability central to material development. This study is investigating both CEM1 based mortars and polyurethane foam to evaluate suitability for use in the construction and repair of buildings. High density polyurethane foam possesses sufficient strength and density to be a viable structural material; however, the fresh properties of the material following mixing of components present a challenge as the material exhibits lateral expansion and excessive deformation prior to curing. Microparticles were added to high density foam to investigate the provision of rigidity during curing, however the particles promoted the foaming reaction, reducing density, strength and structural viability. Mortar mixes under investigation placed the emphasis upon workability and minimisation of constituent segregation, while mindful of the material still needing to possess sufficient buildability in order to prevent excessive deformation of extruded layers while deposited material remains in a fresh state.