聚丙烯纤维、偏高岭土和细砂对水硬石灰改性的研究

Research on the modification of hydraulic lime by polypropylene fiber,metakaolin and fine sand

为改善水硬石灰的力学性能,适当提高其抗压与抗折强度,本工作设计并制备了添加不同配比的聚丙烯纤维、偏高岭土和细砂的水硬石灰,并对其力学强度,矿物成分和微观形貌进行试验研究。结果表明,单独添加30%偏高岭土、0.1%聚丙烯纤维或者50%石英砂的水硬石灰抗压强度相对较高。在偏高岭土-水硬石灰中,单独添加0.1%短长度聚丙烯纤维或者共同加入0.1%聚丙烯纤维和50%石英砂可以提高其长期抗压强度。添加聚丙烯纤维还可以提高水硬石灰抗折强度。钙铝水合物不稳定和长期抗压强度下降有关,添加1%聚丙烯纤维可以提高碳酸化反应。聚丙烯纤维还能够增大水硬石灰内部的摩擦力和锚固力。在南京市罗廊巷太平天国建筑壁画保护中,对于地仗层脱落部位的修补采用改性水硬石灰进行了局部应用,效果良好。

In order to improve the mechanical properties of hydraulic lime and to appropriately increase its compressive and flexural strength,we designed and prepared hydraulic lime with different proportions of polypropylene fiber,metakaolin and fine sand,and experimentally studied the mechanical strength,mineral composition and morphology of each mixture.The results show that the compressive strengths of hydraulic lime mixtures containing 30%metakaolin,0.1%polypropylene fiber or 50%quartz sand only are relatively higher.Metakaolin-hydraulic lime presents improved long-term compressive strength when 0.1%short-length polypropylene fiber is added alone or 0.1%polypropylene fiber and 50%quartz sand are added together.The flexural strength of hydraulic lime containing polypropylene fiber is also increased.The decrease of long-term compressive strength is related to the instability of calcium-aluminum hydrate,and the carbonation reaction can be increased by adding 1%polypropylene fiber.The friction and anchoring forces can also be increased by adding polypropylene fiber.Modified hydraulic lime was used in the conservation of architectural murals of the Taiping Heavenly Kingdom at Luolang Lane in Nanjing.Its application to the local restoration of ground layers achieved good effects.