3D打印细石混凝土调配及其可打印性和力学性能

Preparation of 3D Printable Concrete with Small Coarse Aggregate and Its Printability and Mechanical Properties

摘要:

为了将细石混凝土（SAC）现场调配成3D打印油墨，探究了不同增稠材料对SAC工作性能和流变性的影响，研究了3D打印SAC 的早期力学性能，同时采用3D打印机制备了3D打印SAC 试件，并对其开展了28 d强度试验. 结果表明：SAC二次搅拌过程中，添加占胶凝材料用量0.10%的纤维素醚（HPMC）、1.50%的偏高岭土或5.00%的水泥能够满足3D打印SAC 对工作性能的要求；0.10%的HPMC能够显著提高二次搅拌后SAC的塑性黏度，对挤出力的增长影响较小，这有利于3D打印SAC 的挤出性和工作时间；3D打印SAC 的力学性能具有各向异性，与浇筑试件相比，其28 d抗压强度降低了20.03%~40.46%，抗折强度提高了17.23%~19.54%.

Abstract:

In order to prepare 3D printable ink based on small coarse aggregate concrete （SAC） on site， the effect of different viscosity materials on the workability and rheological properties of SAC were investigated. The early age mechanical properties of 3D printable SAC were studied. At the same time， the 28 days strength of 3D printable SAC which printed by 3D printer were carried out. The results show that the addition of 0.10% hydroxypropyl methyl cellulose （HPMC）， 1.50% metakaolin or 5.00% cement in the secondary mixing process of the SAC can meet the workability requirements of 3D printable SAC. HPMC with the dosage of 0.10% has great effect on the enhancement of plastic viscosity but limited effect on the enhancement of extrusion force， which is positive to the extrudability and working time. The mechanical properties of 3D printable SAC are anisotropic. Compared to the casted specimen， the compressive strength of 3D printable SAC is 20.03%-40.46% lower and the flexural strength is 17.23%-19.54% higher at 28 days.