What Are the Raw Materials of UHPC? In-Depth Analysis of Qinglong's UHPC Raw Material System

The exceptional performance of UHPC (Ultra-High Performance Concrete) stems from its precisely proportioned system of raw materials. As a professional manufacturer with 28 years of experience in the industry, Qinglong UHPC systematically analyzes the composition of UHPC raw materials and their functional mechanisms based on extensive experimental data and production practice. A complete UHPC formula comprises five major categories of raw materials—cementitious materials, reinforcing fibers, aggregates, chemical admixtures, and mineral admixtures—each of which must meet strict technical specifications.

In the Shenzhen Yirui Biotech Building project, the raw material system adopted by Qinglong UHPC is representative: Grade 52.5 low-alkali cement (alkali content ≤0.6%) accounts for 25%, Elkem silica fume (SiO₂≥92%) accounts for 12%, quartz sand (particle size 0.1-0.3mm) accounts for 38%, hooked-end steel fibers (length 13mm, diameter 0.2mm) at a volume fraction of 2.5%, and polycarboxylate superplasticizer (water reduction rate ≥35%) accounts for 2.3%. This precise proportioning keeps the compressive strength stable at above 150MPa. Particularly noteworthy, the silica fume in the raw materials significantly improves material density through its filling effect and pozzolanic reaction, while the copper-plated steel fibers achieve a bond strength of 3.5MPa with the cement matrix, ensuring excellent toughness performance.

Precise Proportioning of the Cementitious Material System

Grade 52.5 low-alkali cement is used to ensure early strength development, with alkali content controlled at ≤0.6% to prevent alkali-aggregate reaction; silica fume (specific surface area 18,000-22,000㎡/kg) fills micropores and enhances density; slag powder and fly ash optimize particle gradation and reduce hydration heat. This multi-component cementitious system allows the water-binder ratio to be reduced to below 0.18, laying the foundation for ultra-high strength.

Aggregate Gradation Optimization Technology

Carefully selected quartz sand has a maximum particle size of ≤0.6mm, a fineness modulus of 1.8-2.2, and a mud content of ≤0.3%. Gradation is optimized based on the densest packing theory, reducing the aggregate void ratio to below 20%. In the Wuhan Han Show Theatre project, this precise gradation ensures tight packing between particles, forming a rigid skeleton.

Innovation in Fiber Reinforcement Systems

Copper-plated steel fibers (tensile strength ≥2000MPa) with an aspect ratio of 60-80 are used at a volume fraction of 2-3%; surface treatment improves the bond between fibers and the matrix; fibers of different scales work synergistically to effectively arrest crack propagation. This reinforcement system achieves a flexural strength of 18-25MPa.

Precise Control with Chemical Admixtures

Polycarboxylate superplasticizer with a water reduction rate of ≥35% ensures workability at low water-binder ratios; retarding components control setting time to meet construction requirements; defoamers ensure material density. Qinglong's custom admixtures achieve an initial flow of 700-800mm.

The quality of raw materials directly determines UHPC performance. Qinglong has established strict supplier audits and incoming inspection procedures, requiring every batch of raw materials to pass 28 indicator tests to ensure stable and reliable product performance.