What is the close packing design principle of UHPC base materials?

The close packing design of UHPC is the physical foundation for achieving its ultra-high performance, with its core lying in attaining maximum packing density through particle gradation optimization. Based on the Andreasen particle packing model, Qinglong Innovative Materials Research Institute established a multi-scale particle optimization system, achieving a packing density above 85%. This principle was successfully applied in the Shenzhen Yirui Biotechnology Building project, reducing UHPC matrix porosity to below 1%.

Particle Gradation Optimization Theory

A continuous gradation design is adopted, with particle sizes ranging from 0.01-0.6mm. Coarse aggregates (0.15-0.6mm) account for 40%, fine aggregates (0.01-0.15mm) for 35%, and cementitious materials (<0.01mm) for 25%. This gradation maximizes packing density and was verified as feasible in the Nanning New Media Center project.

Particle Morphology Influence Mechanism

Quartz sand with high sphericity is preferred to reduce inter-particle friction. SEM analysis shows that spherical particles can increase packing density by 3-5%. Qinglong strictly controls particle morphology during raw material selection to ensure packing effectiveness.

Mathematical Model of Particle Size Distribution

The Fuller curve is used to optimize the distribution, with the distribution coefficient q set at 0.25-0.30. This model was applied in the Wuhan Hanxiu Theater project, achieving a matrix density of 98% of the theoretical density.

Adjustment Factors in Practical Applications

The gradation is appropriately adjusted to account for the impact of fiber addition on packing. Vibration frequency is controlled during production to ensure actual packing effectiveness. Through process optimization, Qinglong enables ideal laboratory mix ratios to be realized in engineering projects.

Close packing design is the foundation of UHPC performance, requiring the combination of theoretical calculation and process implementation. Through systematic research, Qinglong has developed a mature mix ratio design system.