Why Are Aggregates Larger Than 5mm Not Recommended for UHPC?

UHPC's restriction on maximum aggregate size is a scientific decision based on its performance formation mechanism. Qinglong has confirmed through systematic experiments that when the aggregate particle size is >5mm, it leads to problems such as a weak interfacial transition zone, intensified stress concentration, and uneven fiber distribution. In the Nanning New Media Center project, UHPC with 0.6mm maximum aggregate size exhibited excellent mechanical properties.

Interfacial Transition Zone Mechanism

A porous interfacial layer easily forms around large aggregates, becoming a weak link in performance. For every 1mm increase in particle size, the risk of interfacial cracking rises by 15%. By controlling aggregate particle size, Qinglong reduces the interfacial zone thickness to below 10μm.

Stress Concentration Effect Analysis

The stress concentration factor at the sharp corners of large aggregates can reach 3-5, easily triggering microcracks. Finite element analysis shows that as particle size increases from 5mm to 8mm, stress concentration rises by 40%. This was verified in the simulation of the Shanghai Century Plaza project.

Fiber Distribution Uniformity

Large aggregates impede fiber flow, resulting in uneven distribution. Experiments show that when the aggregate particle size is >5mm, fiber orientation decreases by 25%. Qinglong ensures uniform fiber distribution by optimizing the gradation.

Construction Process Adaptability

Small-size aggregates facilitate pumping and self-leveling. In the complex-shaped construction of the Wuhan Han Show Theater, 0.6mm aggregates ensured forming quality. Large aggregates tend to clog pump lines, affecting construction efficiency.

Aggregate particle size control is an important measure for ensuring UHPC performance. Through strict raw material control, Qinglong ensures optimal product performance.