采用硅烷偶联剂KH550改性纳米二氧化硅（SiO₂），并将改性前后的SiO₂作为填料，制备二氧化硅/聚丙烯（SiO₂/PP）塑料混凝土材料，通过扫描电子显微镜观察改性前后纳米二氧化硅的微观结构，研究SiO₂的用量对塑料混凝土工作性能、导热性能及耐久性的影响。结果表明：随着填料用量的增加，样品的流动度逐渐降低，工作性能逐渐降低，材料的热导率逐步上升，热量会通过孔隙流失，使保温性降低，但仍然满足相关标准要求。当改性二氧化硅（M-SiO₂）的质量分数为3%时，塑料混凝土的抗压强度最大，为5.66 MPa，同时表现出较佳的耐久性，经过50次抗硫酸盐试验，抗压强度仅下降9.54%。因此，加入质量分数3% M-SiO₂的塑料混凝土具备较好的保温性能。

Nano silica (SiO₂) was modified by silane coupling agent KH550, and SiO₂ before and after modification was used as filler to prepare silica/polypropylene (SiO₂/PP) plastic concrete material. The microstructure of nano silica before and after modification was observed by a scanning electron microscopy, and the effect of SiO₂ dosage on the workability, thermal conductivity, and durability of plastic concrete was studied. The results show that with the mass fraction of filler increases, the flowability of the sample gradually decreases, the working performance gradually deteriorates, the thermal conductivity of the material gradually increases, the heat is lost through the pores, and the insulation performance gradually decreases, but still meets the relevant standard requirements. When the mass fraction of modified silica (M-SiO₂) is 3%, the plastic concrete has the highest compressive strength, reaching 5.66 MPa, and also exhibits superior durability. After 50 times of sulfate resistance test, the compressive strength only decreases by 9.54%. Therefore, the plastic concrete added 3% M-SiO₂ has good thermal insulation performance.