| Construction 3D printing(C3DP),as a green building concept,is highly valued by researchers and the construction industry and has become increasingly popular in recent years.The C3DP yields savings,especially in terms of material wastage,construction time,labour costs,frequent accidents,and injuries on-site.A potential C3DP material should have the characteristics of good flowability,quick-setting,high early-age strength,suitable viscosity,and,most importantly,must be low cost.However,the properties mentioned above are to be adjusted simultaneously for the utilization of the C3DP is a major problem.Based on the above discussion,it can be assumed that in C3DP,simultaneous adjustment of material properties is essential and may have a significant impact on the overall performance of the printed structures.To prepare cheap C3DP materials and promote economic development,the use of industrial solid waste has significant value and importance.Therefore,choosing a reasonable approach is of practical significance in dealing with solid wastes.One of the most efficient methods to process solid wastes is to apply them to the preparation of C3DP material.This way also meets the environmental protection industry and green construction industry requirements.This method of using solid wastes to prepare C3DP materials can realize the purpose of turning waste into treasure.Moreover,the prepared green building materials have high performance.In the current work,the most important thing was to select the solid waste based sulfoaluminate high-activity material(SHAM)as the C3DP material.Then,by using variable amounts of additives(including boric acid,lithium carbonate,and phase change materials(PCM)),the fluidity,setting time,compressive strength,and viscosity were adjusted and optimized at the same time.Different addition ratios are used,and it turns out that the material is suitable for C3DP.Also,by successfully constructing 3D printed structures of different sizes and shapes with the help of different types of printing systems(such as triangular and D-shaped printers),the optimized material efficiency performance was evaluated.Furthermore,compared with other materials and ordinary Portland cement,we observed a significant reduction in material cost and excellent printing performance.Finally,the design idea of a complete 3D printing system is given and designed.The system can be manufactured in the future for the utilization of C3DP.The results show that:(1)Under the condition of the water-cement ratio of 0.28 when 0.05 wt.%of lithium carbonate and 0.1 wt.%of boric acid was added to the material,the suitability of the material for C3DP was achieved.The suitable properties were achieved,such as flowability of 180.7 mm,initial setting time of 42 min,and compressive strengths of 2-h and 28-d were 19.2MPa and 97.5MPa,respectively.By cross-changing,the ratio of boric acid and lithium carbonate,a coordinated adjustment of these three properties was achieved.At the same time,using paraffin as a phase change material(PCM)can provide suitable properties.In the case of the water-cement ratio of 0.19,under the conditions of 70℃ and 10 wt.%of PCM addition ratio,the optimal flowability is 181 mm,the initial setting time is 33 min,and the compressive strengths of 2-h and 28-d are reached about 10.4 MPa and 78.2 MPa respectively.(2)The actual performance of the optimized material has been checked by successfully constructing 3D printed structures using different types of 3D printing systems at various locations.The layer thickness of successful 3D printed structures is in the range of(8 mm to 20 mm),and the layer width of structures is in between(20mm to 50mm).Also,the length of the constructed structure varies between(100 mm to 600 mm),the width of the 3D structures are in the range of(80 mm to 310 mm),and the maximum height of the structure is slightly below 300 mm.Moreover,the peak of a total of 18 layers of the structure was successfully constructed using optimized sulfoaluminate high-activity material However,the time required to complete a fragment of the created structure is approximately 60 seconds to 90 seconds.Additionally,the 3D printed structures have smooth and defect-free surface finish without the collapse or damage of the successive layers.(3)The cost of our prepared solid waste based SHAM material was economical and calculated about 200-300 Yuan/metric ton compared to the ordinary Portland cement,which costs around 400-500 Yuan/metric ton(4)The design idea for the construction 3D printing system has been given and designed.The complete printing system is divided into three main parts:a material mixing system,a material conveying system,and a material extrusion system,and each part of the printing system are designed and assembled separately.It can be manufactured in the future work for the utilization of C3DPTo conclude,this paper studied to optimize the solid waste-based Sulfoaluminate high-activity material properties for the utilization of C3DP purposes.It achieves the performance required to construct 3D printed structures and is eventually successfully used to build 3D printed structures by using small and large 3D printers.This research provides an innovative way to recycle solid waste to produce sulfoaluminate high-activity material,which can be further optimized for the use of green building material,as this research work does. |
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