基于杨木木屑改性的隧道工程透水砂浆性能研究

为研制出一种既能适用于初期支护基面找平又具有一定透水能力的砂浆，将杨木木屑加入砂浆试块中对其进行改性。通过对杨木木屑的降解特性进行分析，并将不同掺量的杨木木屑加入砂浆试块中，改变其养护方式，对其体积密度、孔隙率、吸水率、抗压强度等基本性能指标及微观结构进行测试和分析。由试验结果可知： 1）加入杨木木屑后普通砂浆试块的孔隙率和吸水率均提升了2～3倍，但同时也会使砂浆试块的体积密度和抗压强度降低； 2）内掺碱并加碱溶液养护方式的孔隙率和吸水率最高，体积密度和抗压强度最低。对砂浆试块吸水率和抗压强度进行线性拟合后发现其吸水率和抗压强度呈负相关关系。研究结果表明，通过杨木木屑提升砂浆透水性能是可行的，但是杨木木屑掺量和养护方式对砂浆其他性能的影响还有待进一步研究。

Performance of Permeable Mortar for Tunnel Engineering Based on Poplar Sawdust Modification

To develop a new type of mortar suitable for base surface leveling of primary support with some permeability, poplar sawdust is added into the mortar test block to modify its performance. The degradation characteristics of poplar sawdust are analyzed, and poplar sawdust with different dosages is added into the mortar test block to change its curing mode. Furthermore, the basic performance indices and microstructure, such as volume density, porosity, water absorption, and compressive strength, are tested and analyzed. The results reveal the following: (1) The porosity and water absorption of the mortar test block increase by 2~3 times after the addition of poplar sawdust, but the volume density and compressive strength of the mortar test block decrease. (2) Under the conditions of alkali addition and curing in alkaline solution, porosity and water absorption are the highest, whereas volume density and compressive strength are the lowest. After linear fitting of the water absorption rate and compressive strength of the mortar test block, these factors are found to be negatively correlated. The results show that it is feasible to improve the water permeability of mortar using poplar sawdust, but the influence of poplar sawdust dosage and curing mode on other properties of mortar needs further study.