Mechanical properties of oil well cement stone reinforced with hybrid fiber of calcium carbonate whisker and carbon fiber

To decrease the brittleness of oil well cement stone, the effects of carbon fiber, calcium carbonate whisker and hybrid fiber of them on mechanical prosperities of the cement stone were studied by experiments. The microstructures and micromechanical behaviors of the cement stone were investigated using scanning electron microscopy. The strengthening and toughening mechanisms of hybrid fiber were discussed. The experimental results show that: the compressive, flexural, split tensile strengths of the cement stone can be improved effectively with each of carbon fiber, calcium carbonate whisker and hybrid fiber; compared with adding a single fiber, the hybrid fiber can strengthen the cement stone better; the mechanical deformation capacity of the cement stone added the hybrid fiber is significantly improved, and the cement stone shows obvious toughness. Observing the microstructures and micromechanical behaviors of the cement stone and analyzing the reinforcement mechanism of hybrid fiber reveal that, the calcium carbonate whisker and carbon fiber have different sizes, morphologies and performances, which can work in different structure levels and loading stages, controlling generation and development of microcracks and fractures and improving the strength and toughness of the cement stone. Key words: oil well cement stone, carbon fiber, calcium carbonate whisker, mechanical properties, well cementin