One-step formation of an integrated composite structure comprising cured mortar layers and a polyurethane layer by 3D printing

A process of fabricating a multi-layer composite structure by 3D printing, the composite structure comprising at least one cured mortar layer formed by curing of a mortar composition, and at least one polyurethane layer formed by polymerization of a first polyurethane forming composition, wherein

• the mortar composition and the first polyurethane forming composition are dispensed individually and simultaneously via adjacent printing nozzles,
• the mortar composition is modified before or after being dispensed by a second polyurethane forming composition to be a modified mortar composition,
• content of the second polyurethane forming composition is 0.1% to 50% by weight based on total weight of the modified mortar composition,
• pot life t3 of the modified mortar composition is 0.05 to 2 hours,
• an initial setting time t2 of the mortar composition when unmodified is greater than a gel time of the second polyurethane forming composition, and
• the gel time of the second polyurethane forming composition is greater than the pot life t3.