混搅挤一体化快速3D打印实现速凝混凝土可连续建造的验证OA

To address the conflict between the open time and setting time of rapid-setting cementitious materials caused by the"mix-then-convey process"in concrete 3D printing,as well as the consequent failure to meet the continuous construction requirements of building structures,this study adopted an independently developed integrated mixing-stirring-extrusion 3D printing device for rapid-setting concrete.With the innovative design of dual-pipeline separate delivery of dry materials and liquid,plus in-nozzle instant mixing,stirring and extrusion,this technical bottleneck was overcome.Taking rapid-setting magnesium phosphate cement(MPC)mortar as the printing material,this study systematically investigates the evolution law of the number of setting layers of printed components over time,as well as the dynamic matching relationship between the compressive strength of materials at the setting-unset interface(setting line)and the total self-weight stress of unset layers,so as to verify the feasibility of continuous construction of rapid-setting materials using this integrated process.The results show that there are always 4 to 7 unset layers above the set layers of MPC mortar printed components,and the number of unset layers gradually decreases with the progress of printing.The compressive strength of the printed layers at the setting line is always 25.6 times or more of the total self-weight stress of the unset layers,and the strength development rate was 26.7 times or more of the self-weight stress development rate of the unset layers.This indicates that the bottom set layers can continuously support the self-weight of the upper unset layers,confirming that the integrated mixing-stirring-extrusion 3D printing process enables rapid and continuous construction of MPC mortar.The research findings provide a reference for improving the 3D printing efficiency of rapid-setting cementitious materials and optimizing the printing process.