目的 通过对核桃壳进行改性，降低其亲水性、吸水率和微生物降解，改善含核桃壳砂浆的工作性能和耐久性能;增强核桃壳与水泥浆的界面结合，提升含核桃壳砂浆的力学性能。方法 首先，分别用不同浓度的硅烷偶联剂KH560、不同浓度的钛酸酯偶联剂和不同热解温度对破碎核桃壳进行改性处理。然后，用扫描电镜观察改性前后核桃壳表观形貌的变化，用傅里叶红外光谱表征改性前后核桃壳官能团的变化。其次，分别测试改性前后核桃壳静态接触角和吸水率的变化，观察核桃壳与砂浆在界面处的结合情况。最后，用核桃壳部分替代标准砂制备得到砂浆，分别测试各组砂浆的流动度、抗压强度、抗折强度。结果 改性后核桃壳的静态接触角由104.9°分别增加为135.9°(KH组)、133.3°(TO组)和128.5°(TI组)。偶联剂用量越大，核桃壳的吸水率越小。KH组核桃壳1 h和24 h的最小吸水率分别为17.6%和25.5%，分别比对照组低43.6%和35.6%;TI组核桃壳1 h和24 h的最小吸水率分别为17.6%和28.7%，分别比对照组低43.6%和27.5%;TO组核桃壳1 h和24 h的最小吸水率分别为17.5%和34.3%，分别比对照组低43.9%和13.3%。改性后，KH组、TO组、TI组的砂浆流动度均大幅增加，最大流动度分别为250、200、200 mm。轻度热解能明显改善砂浆的力学性能，砂浆的抗压强度和抗折强度最高分别可达41.8、7.12 MPa。结论 3种改性方法均能增加核桃壳的疏水性，降低核桃壳的吸水率，改善砂浆的流动性。KH560改性处理方法引入的酸性物质抑制了水泥水化，导致砂浆力学性能降低。钛酸酯偶联剂部分封堵了核桃壳内表面的孔隙，弱化了水泥浆体与核桃壳的机械咬合，导致砂浆力学性能降低。而轻度热解后，核桃壳表面的灰分和半纤维素部分分解，使多层堆叠形状的木质素结构凸显，增加了核桃壳的比表面积，有利于浆体与核桃壳的结合，从而使砂浆的抗折强度和抗压强度均得到提升。150 ℃条件下轻度热解是提升含核桃壳砂浆综合性能的核桃壳最佳改性方案，在该条件下，砂浆的流动性增加4.6%，抗折强度增加15.6%，抗压强度增加3.2%。同时150 ℃轻度热解在有氧条件下进行，便于操作，而且施工成本不高，有利于在工程中推广应用。

Silane coupling agent has been a highly efficient interface modifier, which can form a binding layer of organic matrix-silane coupling agent-inorganic matrix at the interface to enhance the compatibility between organic aggregate and cement matrix. Titanate coupling agent has a good effect in connecting inorganic fillers and polymer matrix. Mild pyrolysis can enhance the hydrophobicity of biomass materials, kill some bacteria, preventing the fungal degradation of biomass materials. Walnut shell has high content of organic matter and poor compatibility with inorganic cement matrix, so it’s difficult to form effective chemical connection in the interface area, which leads to poor mechanical properties of mortar. Moreover, walnut shell is rich in strong polar hydroxyl groups, has a strong ability to absorb water and moisture, and the mechanical properties of saturated walnut shell are reduced, and it is easier to be biodegraded. When used as aggregate, the bearing capacity is greatly reduced. In this paper, walnut shell was modified by three methods, the effect of modification on the structure and properties of walnut shell was investigated, and the properties of mortar with modified walnut shell as aggregate were further studied.