Study On Preparation And Properties Of 3D Printing Mortar For Buildings Mixed With Aeolian Sand

With the progress of science and the development of the ages,3D printing technology for buildings has emerged as the times require.In recent years,it has been widely studied by scholars at home and abroad.The desert is widely distributed in Inner Mongolia.The application of aeolian sand and 3D printing technology in construction industry can not only alleviate the shortage of building material resources,but also effectively protect the environment and achieve the goal of energy saving and emission reduction.In this paper,aeolian sand was used as aggregate to produce 3D printing mortar.The mix proportion of 3D printing mortar was determined by single factor analysis,maximum bulk density method and orthogonal test analysis.The aeolian sand was mixed with 3D printing mortar to prepare two kinds of 3D printing mortar for buildings with different uses.The working performance,mechanical properties and anisotropy were investigated.At the same time,the printing process was controlled and the calculation formula of relevant parameters was proposed.Details are as follows:(1)The influence of three kinds of additives on the working performance of 3D printing mortar was investigated by single factor method,and the types and dosage range of additives were determined.(2)According to the maximum density theory,the gradation of aeolian sand and quartz sand was optimized.The printability,buildability and surface roughness of the slurry strip were taken as performance indicators to verify the optimal ratio of aeolian sand and quartz sand.Finally,the incorporation proportion of aeolian sand was obtained.(3)Through the analysis of orthogonal test,the mixing ratio of 3D printing mortar for two kinds of aerated sand building was finally determined with the flow degree and strength of the jump table as the technical indexes.The orthogonal test results were verified,and the curing method suitable for 3D printing mortar was explored.It was found that through the orthogonal test,the fluidity and slump of 3D printing mortar of two groups of aeolian sand buildings met the printing requirements.In addition,different curing conditions showed different strength indexes.Natural curing conditions were conducive to the development of flexural strength of 3D printing mortar,and standard curing conditions were more conducive to the development of compressive strength of 3D printing mortar.(4)By using the printing system,the printing performance of 3D printing mortar mixture ratio of two groups of aerated sand building was measured.The results showed that the printing performance of Q group with strength as design index was the same as that of the reference group,but the extruded strip surface was smoother and the 28d compressive strength was the same as that of the reference group.Group X with the best printing effect as the design index showed better extrudate ability,smoother and more beautiful strip surface,and longer opening time;At the same time,the buildability was slightly worse than the reference group,the fluidity was slightly larger,and the 28d compressive strength was higher.(5)By mechanical cutting the printed test block,compared with the corresponding pouring specimens,the specimens were loaded from X,Y and Z directions,respectively.The influence mechanism of mechanical properties and anisotropy of 3 D printing were analyzed.It was found that the mechanical properties of 3D printed specimens were anisotropic.The anisotropic laws of printed specimens were similar with different material mix ratios,but the dispersion degrees of anisotropic differences were different,and different laws were presented with the increase of age.The mechanical anisotropy of flexural strength of the specimens after cured for 28days was as follows:casting piece was bigger than that of f_Z,f_Z was higher than f_Y,f_Y was greater thanf_X.The mechanical anisotropy of compressive strength of the specimens was as follows:f_Z was approach tof_Y,f_Z and f_Y were greater thanf_X,f_X was bigger than casting piece.(6)The control points of 3D printing process were put forward.Taking the volume(flow rate)of the extrusion strip per unit time as the intermediate parameter,the mechanical operation parameters were correlated with the design parameters,and the coordination formula between the screw speed and the printing speed required to meet the design printing target was obtained,and the mortar was verified.Two methods to improve the limit printing height were proposed for the discriminant analysis of the stability of printing components;Finally,through the quantitative calculation of the amount of model materials,the purpose of parametric control of the whole process of3D printing was achieved.(7)The two groups of 3D printing mortar mixed with aeolian sand configured in this paper were feasible after printing verification,which could meet the needs of different printing,and the printing effect was better than the benchmark ratio.The combination of aeolian sand and 3D printing further played the advantages of 3D printing such as green environmental protection,energy saving and emission reduction.