Effect of UiO-66 and UiO-66-NH2 Synthesized Using In Situ Self-Assembly on the Mechanical Properties of Cement-Based Materials

To meet the demands of the construction industry for cement-based materials, nanomaterials are frequently used as additives to enhance the mechanical properties and durability of cement-based materials. This study investigates the effects of UiO-66 and its amino-functionalized derivative UiO-66-NH2 on the mechanical properties, hydration process, and microstructure of cement-based pastes with a water-to-cement ratio of 0.4. The experimental results indicate that compared to the blank group (pure cement), the addition of 0.05% of these two metal-organic frameworks (MOFs) can increase the compressive strength of cement pastes by 13.2% and 21.8%, respectively, and the flexural strength by 21.2% and 25.5%, respectively, at 28 days. X-ray diffraction results demonstrate that UiO-66 and UiO-66-NH2 exhibit similar stability behavior in cement pore solutions. The incorporation of these two MOFs enhances hydration levels in the cement hydration process, fostering increased production of hydrated calcium silicate gel. Concurrently, it fine-tunes the cement's pore structure, amplifying its mechanical strength. This research confirms UiO-66 and UiO-66-NH2 as promising nanocement additives, laying a theoretical groundwork for incorporating UiO-66-type MOFs in composite materials based on cement.