微米和纳米Al2O3对水泥基材料力学与耐久性的影响

为了明确微米和纳米Al₂O₃对水泥基材料力学性能与耐久性的改性作用,采用细度分别为1 μm和10 nm的Al₂O₃替代水泥,制备低水胶比水泥基材料。通过宏观和微观测试手段,分析微米和纳米Al₂O₃对水泥基材料力学性能与耐久性的影响规律,并探析其作用机理。试验表明:掺量为0.5%~4.0%的微米Al₂O₃和纳米Al₂O₃能增强水泥基材料的力学性能,降低其干燥收缩;0.5%~2.0%微米Al₂O₃和0.5%~4.0%纳米Al₂O₃能降低水泥基材料的渗透系数,但4.0%微米Al₂O₃会增大水泥基材料的渗透系数。相对而言,纳米Al₂O₃对水泥基材料的改性作用优于微米Al₂O₃。电镜扫描和文献研究结果发现,纳米Al₂O₃和微米Al₂O₃在水泥基材料水化、硬化过程中发挥尺寸效应、填充效应和表面活性效应,进而达到增强水泥基材料的力学性能和耐久性的目的。研究成果为水泥基材料的改性提供试验基础。

Effects of Micron-Al2O3 and Nano-Al2O3 on Mechanical Properties andDurability of Cement-based Material

By replacing cement with Al₂O₃ of 1 μm and 10 nm, respectively, cement-based materials with low water-binder ratio were prepared for researching the modification effect of micron-Al₂O₃ and nano-Al₂O₃ on the mechanical properties and durability of cement-based material. Macro-and-microscopic approaches were adopted to examine the change law of mechanical performance and durability and to analyze the modification mechanism. Results demonstrated that both micron-Al₂O₃ and nano-Al₂O₃ at a dosage of 0.5%-4.0% could enhance the mechanical performance while reducing the drying shrinkage of cement-based material. Micron-Al₂O₃ at a dosage of 0.5%-2.0% or nano-Al₂O₃ at a dosage of 0.5%-4.0% could reduce the permeability coefficient; however, a 4.0% micron-Al₂O₃ would increase the permeability coefficient. The modification effect of nano-Al₂O₃ is superior to that of micron-Al₂O₃. SEM result and previous research findings prove that in the process of cement-based material’s hydration and hardening, micron-Al₂O₃ and nano-Al₂O₃ ameliorate the mechanical performance and durability through size effect, filling effect and surface activity effect.