What Is the Dense Packing Design Principle of UHPC Base Materials?

The close packing design principle of UHPC is based on the densest packing theory in granulometry. By optimizing the grading of particles of different sizes, it minimizes the porosity of the matrix. The core of this principle is to adopt a continuous grading system, in which the voids between large particles are filled by medium particles, and the voids between medium particles are filled by small particles, ultimately achieving maximum packing density.

In practical applications, the particle grading design of high-quality UHPC usually follows the Fuller curve theory, optimally combining particles with sizes ranging from 0.1μm to 1mm. Take the mix proportion of Qinglong UHPC as an example: cement particles (1-50μm) serve as the basic skeleton, quartz sand (0.1-0.6mm) acts as the main filler, and silica fume (0.1-1μm) fills micropores. This multi-scale particle system reduces porosity to 2-3%. Testing with a laser particle size analyzer shows that the packing density of this grading design can reach over 85%, far exceeding the 60-65% of ordinary concrete.

Particle Grading Optimization Technology

A three-grade system is adopted: coarse aggregate (0.6-1mm) accounts for 30%, fine aggregate (0.1-0.6mm) for 40%, and ultra-fine powder (0.1-100μm) for 30%. This grading achieves the densest packing.

Particle Size Distribution Control Methods

Real-time monitoring with a laser particle size analyzer; controlling the particle size distribution coefficient at n=0.3-0.5; ensuring continuous distribution of particles of different sizes. These controls achieve optimized grading.

Measures to Improve Packing Density

Determining the optimal mix proportion through compressed packing tests; using particle materials with high sphericity; controlling particle surface morphology. These measures improve packing density.

Pore Structure Improvement Effects

Total porosity is reduced to below 3%; harmful pores (>50nm) account for less than 15%; micropores (<10nm) account for more than 60%. This structure significantly improves performance.

Close packing design is the foundation of UHPC performance. Scientific grading optimization can significantly enhance material performance. Through precise grading design, Qinglong UHPC products achieve internationally advanced performance levels.