The　innovative　3D　printing　has　been　successfully　applied　to　layeredly　build-up　construction-scale　structures　through　the　extrusion　of　various　cementitious　materials.　Favourable　buildability　of　fresh　cement　mixture　and　the　hardened　properties　of　the　printed　structures　are　essential　requirement　for　the　application　of　3D　concrete　printing.　This　paper　firstly　proposed　a　3D　printable　cement　mixture　containing　40%　mining　tailings.　The　influence　of　paste　age　on　the　buildability　of　forty-layer　structure　was　evaluated,　as　well　as　the　bending　resistance　of　prism　specimen　sawed　from　the　printed　structure.　The　bonding　between　layers　is　a　critical　factor　that　influences　the　structural　capacity.　In　particular,　the　weak　bonding　interface　formed　in　the　layered　extrusion　process　was　identified　through　high-resolution　X-ray　CT　scanning.　It　is　necessary　and　desirable　for　the　cement　paste　to　perform　both　well　buildability　and　mechanical　performances.　Thereafter,　a　proper　amount　of　viscosity　modify　agent　(VMA)　was　used　to　improve　the　structural　integrity　by　increasing　the　contact　behaviour　between　the　adjacent　extruded　layers.　Meanwhile,　the　impact　of　curing　method　on　the　hardened　properties　of　3D　printed　structures　was　accessed.　Results　indicated　that　the　prepared　tailing　mortar　achieved　sufficient　buildability　to　be　used　in　an　extrusion-typed　3D　printer　at　the　paste　age　of　45　min.　The　mould-cast　specimens　process　flexural　strength　of　7.87　MPa.　In　contrast,　the　flexural　strength　of　printed　specimens　values　5.22　MPa　and　12.93　MPa,　respectively,　after　the　addition　of　1.5%　VMA　and　90　degrees　C　steam　curing.