Why Should UHPC Not Use Aggregates Larger Than 0.6mm?

UHPC limits the maximum aggregate size to no more than 0.6mm based on its material design principles. Oversized aggregates destroy the material's homogeneity, create stress concentration, and affect fiber distribution, thereby reducing material performance. This limit is a key factor in ensuring UHPC achieves ultra-high performance.

From a materials science perspective, there is a matching relationship between aggregate size, fiber length, and component thickness. When the aggregate size exceeds 0.6mm, it accounts for an excessive proportion in thin-walled components (20-30mm thick), affecting the three-dimensional distribution of fibers; meanwhile, weak zones easily form at the interface between large aggregates and cement paste. Test data shows that when aggregate size increases from 0.6mm to 1.2mm, UHPC compressive strength drops by 15% and flexural strength decreases by 25%. This is why high-quality UHPC strictly controls aggregate size.

Impact on Fiber Distribution

Large aggregates hinder uniform fiber distribution; fiber orientation is affected; local fiber density is uneven. These effects reduce reinforcement efficiency.

Impact on Interface Structure

Large aggregates enlarge the interfacial transition zone; interface defects increase; stress concentration becomes significant. These effects weaken performance.

Impact on Component Adaptability

Improper proportion in thin-walled components; affects flowability and compactness; surface quality is difficult to guarantee. These effects limit applications.

Impact on Performance Uniformity

Increased dispersion of mechanical properties; local variations in durability; reduced quality stability. These effects reduce reliability.

Aggregate size control is a critical part of quality assurance. Qinglong UHPC strictly implements aggregate control standards to ensure excellent product performance.