纳米CaCO3对水泥基材料性能与结构的影响及机理

采用超声波分散方式将纳米CaCO_3掺入水泥基材料,研究了不同掺量纳米CaCO_3对水泥基材料性能与结构的影响,并利用X射线衍射和扫描电镜分析其影响机理.结果表明:掺入纳米CaCO_3后,水泥基材料流动度降低,浆体表观密度增大,抗折和抗压强度提高.纳米CaCO_3掺量为1.5%(质量分数)时,对水泥基材料的力学性能提高最为显著,纳米CaCO_3掺量过多则不利于强度发展.纳米CaCO_3的掺入会加速水泥的水化,早期使水化产物Ca(OH)_2等增加;纳米CaCO_3改善了界面结构和水泥石结构,使水泥基材料的结构变得更加均匀密实.结果显示纳米CaCO_3掺入后对水泥基材料的力学性能与结构有利.

Influence and Mechanism of Nano-CaCO3 on Properties and Structures of Cement-based Materials

Nano-CaCO3 was adopted into cement-based materials in the ultrasonic dispersion method. The influence of nano-CaCO3 with different contents on the properties and structures of cement-based materials was studied, and its mechanism was investigated by X-ray diffraction and scanning electron microscope. The results show that the fluidity is decreased, the apparent density of cement paste is increased, and the flexural strength and compressive strength are improved due to the addition of nano-CaCO3. The mechanical properties of cement-based materials containing nano-CaCO3 of 1.5% (in mass) are significantly improved. However, excessive dosage of nano-CaCO3 goes against the improvement of strength. The hydration can be accelerated, the hydration products such as Ca (OH)2 increase with the addition of nano-CaCO3 at the early age; the interface transition zone between aggregate and cement paste and the microstructure of hardened cement paste are greatly improved so that the whole structure can get more dense and homogeneous. The above results indicate that the incorporation of nano-CaCO3 is good for the physical properties and structures of cement-based materials.