聚羧酸减水剂对原位吸水树脂改性天然水硬性石灰流变特性的影响

Effect of polycarboxylic plasticizer on the rheological properties of in-situ absorbent polymer modified natural hydraulic lime

原位超吸水树脂(SAP)改性天然水硬性石灰(NHL)复合材料(SAP/NHL)是一种新兴的石窟寺裂隙灌浆修复材料,但作为灌浆材料其仍存在流动性差的缺点,难以满足施工要求.高效减水剂的使用不仅可以增加浆体的流动性,还可提高强度和耐久性,其中聚羧酸减水剂因其优异性能,近年来被广泛使用.以聚羧酸减水剂(PCE)作为外加剂对SAP/NHL进行改性,通过TOC、Zeta电位仪对PCE的吸附进行了测试,通过流动性测试表征了浆体流动性,通过旋转流变仪、超景深显微镜对浆体流变特性和微观结构进行了表征,使用万能试验机对固化浆体抗压强度进行了测试.结果表明,PCE能通过静电斥力和空间位阻的协同作用有效改善浆体流变特性并最终改善流动性(>337 mm).此外PCE在小剂量掺加后会提高固化浆体的抗压强度(28 d强度从4.8 MPa至5.9 MPa),过量添加会降低强度.

In-situ superabsorbent polymer(SAP)modified natural hydraulic lime(NHL)composite(SAP/NHL)is an ideal material for grouting and repairing cracks in grotto.As a grouting material it still has the disadvantage of poor flowability,which makes it difficult to meet construction requirements.The use of high efficiency plasticizer can not only increase the fluidity of the paste,but also improve the strength and durability,of which polycarboxylic plasticizer have been widely used in recent years due to their excellent performance.In this paper,PCE was used as an admixture to modify SAP/NHL.The adsorption of PCE was tested by TOC and zeta potential meter,the fluidity of the paste was characterized by fluidity test,the rheological properties and microstructure of the paste were characterized by a rheometer and ultra-deep field microscope,and the compressive strength of the cured paste was tested by universal testing machine.The results show that PCE can effectively improve the rheological properties and ultimately the flowability of the paste(>337 mm)through the synergistic effect of electrostatic repulsion and spatial resistance.In addition,PCE increases the compressive strength of the cured paste in small doses(28 d strength from 4.8 MPa to 5.9 MPa)and decreases in excessive doses.