Effect of Vibration Mixing on the Mechanical Properties of Carbon Nanotube-Reinforced Ultra-High-Performance Concrete

Vibration mixing, characterized by the high-frequency vibrations of the mixing shaft, can enhance the mechanical properties of ultra-high-performance concrete (UHPC). However, the effects of vibration mixing on carbon nanotube (CNT)-reinforced UHPC have not been previously reported. To investigate the impact of vibration mixing on the properties of CNT-reinforced UHPC, a comparative study was conducted using different vibration mixing durations and twin-shaft mixing. The results indicate that for CNT-reinforced UHPC, vibration mixing achieves better flowability, higher wet apparent density, and superior mechanical properties in shorter mixing times compared to twin-shaft mixing, making it a more favorable method. Considering vibration mixing times ranging from 3 to 7 min, the optimal time was found to be 3 min, during which the axial compressive strength increased by 3.3%, the elastic limit tensile strength and tensile strength improved by 14.6% and 15.8%, respectively, and the initial cracking strength and flexural strength increased by 12.6% and 13.4%, respectively, compared to values after 10 min of twin-shaft mixing.