Synergistic effect of magnesium oxide expansion agent and nano-silicon dioxide in UHPC
In the research and application of ultra-high performance concrete (UHPC), the combined use of magnesium oxide expansion agent and nano-silica has become an effective way to improve the performance of materials. This paper deeply explores the mechanism of action of these two materials in UHPC and their influence on mechanical properties, durability and processing properties, providing a scientific basis for the further optimization of UHPC.
Ultra-high performance concrete (UHPC) is increasingly widely used in the construction industry due to its excellent mechanical properties and durability. In order to further improve the performance of UHPC, researchers are constantly exploring new materials and technologies. Among them, the synergistic effect of magnesium oxide expansion agent and nano-silica has become an important research direction for improving the performance of UHPC.
The role of magnesium oxide expansion agent
Magnesium oxide expansion agent produces volume expansion through hydration reaction, effectively compensating for the shrinkage of UHPC and reducing the occurrence of cracks. In UHPC, the role of magnesium oxide expansion agent is not limited to improving crack resistance, but also can support cement stone through crystal growth, further improving the density and strength of the material[^19]. In addition, the morphology of the hydration product of magnesium oxide expansion agent under high temperature and high pressure environment also has a significant effect on the durability of UHPC.
Synergistic effect of nano-silica
The addition of nano-silica further reduces the porosity of the material and enhances the overall performance of the material by filling the tiny pores inside UHPC. The high specific surface area and activity of nano-silica enable it to fully react chemically with cement-based materials to form a denser cement stone structure. This optimization of the microstructure not only improves the mechanical properties of UHPC, but also significantly improves its durability.
Improvement of mechanical properties
The synergistic effect of magnesium oxide expansion agent and nano-silica significantly improves the mechanical properties of UHPC. Studies have shown that the modified UHPC has significantly improved in compressive strength, tensile strength and shear strength. Especially under dynamic loads, UHPC exhibits excellent dynamic mechanical properties, including higher impact strength and toughness.
Enhanced durability
In terms of durability, UHPC has shown excellent anti-carbonization, anti-chloride ion erosion and anti-freeze-thaw properties through the modification of magnesium oxide expansion agent and nano-silica. The improvement of these properties makes the application prospects of UHPC in harsh environments broader
The synergistic effect of magnesium oxide expansion agent and nano-silicon dioxide provides new possibilities for improving the performance of UHPC. Through this synergistic modification, the mechanical properties, durability and processing properties of UHPC have been significantly improved, laying the foundation for the application of UHPC in more fields. Future research will further explore the optimal ratio and action mechanism of these two materials to maximize the performance of UHPC.