羟丙基甲基纤维素对3D打印砂浆性能的影响

Effect of Hydroxypropyl Methylcellulose Ether on Properties of 3D Printing Mortar

通过研究不同掺量羟丙基甲基纤维素(HPMC)对3D打印砂浆可打印性能、流变性能及力学性能的影响规律,探讨了HPMC的适宜掺量,并结合微观形貌分析其影响机理.结果表明:砂浆流动度随着HPMC掺量增加而降低,即可挤出性随着HPMC掺量增加而降低,但流动性保持能力提高,加入适宜掺量的HPMC后砂浆仍具有良好的可挤出性;自重下形状保留率、贯入阻力均随HPMC掺量增加而显著增加,即随HPMC掺量增加,可堆叠性提高,可打印时间延长;从流变学的角度来看,随着HPMC掺量的增加,浆体表观黏度、屈服应力和塑性黏度显著增大,可堆叠性提升;触变性随HPMC掺量增加而先增大后减小,可打印性能提升;HPMC掺量过高会引起砂浆孔隙率增大、强度下降,建议HPMC掺量不超过0.20%.

The effects of different contents of hydroxypropyl methylcellulose ether(HPMC)on printability,rheology and mechanical properties of 3D printing mortar were studied.The suitable content of HPMC was determined,and its influence mechanism was analyzed by micro⁃morphology.The results reveal that the fluidity of mortar decreases with increasing HPMC content,so the extrudability decreases with HPMC content.But the fluidity retention ability increases,the mortar with HPMC still has good extrudability.The shape retention rate under self⁃weight and penetration resistance increase significantly with HPMC content,so the buildability and the printable time increase with increasing HPMC content.From the perspective of rheology,with the increase of HPMC content,the apparent viscosity,yield stress and plastic viscosity of the paste increase significantly,thus the buildability increases.The thixotropy increases at first and then decreases with increasing HPMC content,so the printability increases.However,higher HPMC content will lead to the increase of mortar porosity and the decrease of mortar strength.So it is recommended that the content of HPMC should not exceed 0.20%.