Study on the impermeability and microstructure of cement mortar blended with silicon carbide nanowhiskers

Silicon carbide (SiC) nanowhiskers have many application prospects owing to their excellent mechanical properties, thermal conductivity, and good chemical stability. Herein, we examined the effect of enhancing the mechanical properties and impermeability of cement mortar (CM) by improving the microstructural compactness and reducing the porosity after mixing CM using SiC nanowhiskers. Macroscopic and microscopic tests and analyses of CM blended with different amounts of SiC nanowhiskers were performed using an electro-hydraulic flexural and compressive testing machine, cement mortar penetration tester, field-emission scanning electron microscopy, energy-dispersive spectrometry, X-ray diffraction, and three-dimensional X-ray microscopy. Results demonstrated that the incorporation of SiC nanowhiskers can lead to the following: (1) enhance the mechanical properties of CM, especially in the early stage; (2) fulfill the role of crystal nucleation and promote the hydration reaction; (3) fill the pores, play the role of micro-aggregate filling, improve the compactness, and reduce the porosity and relative permeability coefficient; and (4) play a bridging role and connect internal structures. Our results provide a valuable reference for developing nanowhisker-blended CM.