纳米二氧化硅改性混凝土宏观性能及微观调控机理分析

Analysis on Macroscopic Property and Microcoscopic Control Mechanism of Nano-SiO2 Modified Concrete

系统研究了纳米SiO2对水泥净浆流动性、水泥砂浆强度、混凝土强度和动弹性模量、混凝土渗透性能的影响,并采用X射线衍射(XRD)分析了不同掺量纳米SiO2对混凝土不同水化阶段水化产物的影响规律,同时借助电镜扫描(SEM)分析了水化产物微观结构受到的影响,从宏观性能和微观机理两方面探讨了纳米SiO2对水泥基材料的影响。结果表明,纳米SiO2会影响水泥水化尤其是早龄期水化速度,从而提高混凝土和砂浆强度,提高混凝土的抗渗性能,降低混凝土的动弹性模量。一定范围内,随着纳米SiO2掺量的增加,水泥水化产物受影响的程度逐渐增大,通过XRD和SEM分析水化产物微观结构变化规律,发现与宏观力学性能和耐久性能吻合较好。纳米SiO2本身的特性(粒径大小、表面活性、分散性能等)决定其对水泥水化过程和产物的影响程度。

Effect of nano-SiO2 on the fluidity of cement slurry,the strength of cement mortar,and the strength,elastic modulus and permeability of concrete were studied.The influence law of nano-SiO2 with different content on the different stages of concrete hydration products was analyzed using X-ray diffraction(XRD).At the same time,the microstructure of hydration products was analyzed with scanning electron microscope(SEM).The effect of nano-SiO 2 on cement-based materials was discussed from the macroscopic properties and microscopic mechanism.The results show that nano-SiO2 can affect the hydration process of cement and improve the strength of concrete and mortar.The impermeability of concrete is significantly improved.And,the dynamic elastic modulus of concrete is reduced.In a certain range,with the increase of nano-SiO 2 content,the influence of cement hydrate gradually increases.XRD and SEM analyze the microstructure changes of hydration products,which are in good agreement with the macroscopic mechanical properties and durability.The properties of nano-SiO2 itself(particle size,surface activity,dispersion,etc.)determine the degree of its influence on the hydration process and products of cement.