The present disclosure envisages an apparatus for 3D printing concrete structures. The apparatus comprises a printing platform (110), a frame (115) disposed on the platform (110), a support material dispensing unit (120), an extrusion unit (105), and a control unit. The frame (115) has vertical bars (119) and guide rails (117) connecting each bar. The support material dispensing unit (120) is movably mounted on the frame (115), to dispense support material on the platform (110). The extrusion unit (105) is movably mounted on the frame (115), to deposit layers of a construction material on the platform (110). The control unit is coupled to the support material dispensing unit (120) and the extrusion unit (105). The control unit receives input signals and processes the input signals to enable actuation and displacement of the support material dispensing unit (120) and the extrusion unit (105) for 3D printing a concrete structure.