延安清凉山石窟砂岩表层防风化保护材料研究

Research on surface weathering-resistant materials for sandstones in Qingliangshan,Yan'an

针对陕西延安清凉山石窟砂岩由于水/盐运移活动频繁导致的病害,本研究选用商用硅酸酯(KSE-300)和现代合成两性离子聚氨酯(ZPU)、POSS杂化两性离子聚氨酯(POSS-D+ZPU)、CaCO_(3)寡聚体交联两性离子聚合物[CaCO_(3-)c-P(MPC-ran-MPS)]、POSS增强柔性硅氧烷(POSS-AHAPTMS)对砂岩进行实验室表面渗透保护试验,并对比评估保护性能。结果表明,分散体尺寸小、成膜性相对较差,且能够与砂岩基体化学键合的CaCO_(3-)c-P(MPC-ran-MPS)和KSE-300保护材料更易向砂岩内部渗透、且不易改变砂岩原有孔隙结构;与砂岩极性匹配较高的CaCO_(3-)c-P(MPC-ran-MPS)、ZPU和POSS-D+ZPU保护材料对砂岩的表面色度影响较小;CaCO_(3-)c-P(MPC-ran-MPS)保护材料因兼具加固与水/盐运输功能而使砂岩表现出最佳的抗盐结晶循环性能,而疏水性ZPU和KSE-300因阻碍了砂岩内部水/盐运移路径而使砂岩在盐结晶循环中表现出断裂和层状剥落的风险。综上,CaCO_(3-)c-P(MPC-ran-MPS)保护材料更适用于砂岩表层预防性抗盐结晶破坏。

In view of the diseases caused by frequent water/salt transport activities in the Qingliangshan Grottoes sandstone in Yan'an,Shaanxi,we selected commercial silicate ester(KSE-300)and modern synthetic zwiterionic polyurethane(ZPU),POSS hy-brid zwitterionic polyurethane(POSS-D+ZPU),CaCO_(3) oligomer crosslinked zwitterionic polymer[CaCO_(3-)c-P(MPC-ran-MPS)],and POSS enhanced flexible siloxane(POSS-AHAPTMS)to conduct surface penetration protection tests on the sandstone,comparing and evaluating the protection performance.The results showed that CaCO_(3-)c-P(MPC-ran-MPS)and KSE-300 penetrated into the sandstone easily without altering the pore structure of sandstone obviously due to their small sizes of dispersions,relatively poor film-forming properties and chemically-bonded abilities with sandstone.In addition,the protective materials of CaCO_(3-)c-P(MPC-ran-MPS),ZPU and POSS-D+ZPU were observed to slightly change the color of sandstone due to their similar polarity to sandstone.We also found that hydrophobic ZPU and KSE-300 hinder the internal water/salt transport pathway of sandstone,leading to the risk of fractures and layered peeling in the salt crystallization cycle.In summary,CaCO_(3-)c-P(MPC-ran MPS)protective material is more suitable for preventing salt crystallization damage on the surface of sandstone.