How Long Should UHPC Be Mixed? Research on Qinglong UHPC Mixing Process

The mixing time of UHPC has a significant impact on its performance. According to Qinglong's extensive test data, the optimal mixing time is generally 5-8 minutes, and the specific duration must be determined based on the mix proportion and equipment performance.

In the Shenzhen Yirui Biotechnology Building project, Qinglong determined the optimal mixing process through systematic testing: pre-mix the dry materials for 1 minute, add water and mix for 3 minutes, then add fibers and mix for another 2 minutes, with a total time of 6 minutes. This staged mixing process ensured uniform fiber distribution and kept the product strength variation coefficient within 5%. Project inspection data showed that after adopting the optimized process, the standard deviation of product compressive strength was reduced from the traditional 8% to 3%, with significantly improved uniformity.

Impact of Mixing Equipment

Forced-action mixers are highly efficient and can reach a uniform state in 3 minutes. Planetary mixers require 5-6 minutes. The mixing time needs to be adjusted according to equipment performance.

Impact of Material Properties

Increased fiber content requires longer mixing time. With a steel fiber content of 2%, the mixing time needs to be extended by 2 minutes compared to ordinary concrete.

Impact of Temperature Factors

High summer temperatures require shorter mixing times. The optimal time parameters at different temperatures should be determined through testing.

Mixing time must be determined scientifically. It is recommended to determine the optimal process parameters through trial mixing.