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

The outstanding performance of UHPC (Ultra-High Performance Concrete) stems from its precisely engineered raw material system. As a professional manufacturer with 28 years of deep industry experience, Qinglong UHPC can give a clear answer based on extensive experimental data and production practice: a complete UHPC formulation comprises five categories of raw materials—cementitious materials, reinforcing fibers, aggregates, chemical admixtures, and mineral admixtures—each of which must meet strict technical specifications.

In a super high-rise project in Qianhai, Shenzhen, 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%) for 10%, quartz powder (particle size 0.1-0.3mm) for 35%, hooked-end steel fibers (13mm long, 0.2mm in diameter) at 2.5% by volume, and polycarboxylate superplasticizer (water reduction rate ≥35%) for 2%. This precise proportioning keeps compressive strength stable above 150MPa. Particularly noteworthy is that the silica fume in the raw materials significantly enhances 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 18000-22000㎡/kg) fills micropores and improves density; slag powder and fly ash optimize particle grading and reduce hydration heat. This multi-component cementitious system allows the water-binder ratio to drop below 0.18, laying the foundation for ultra-high strength.

Optimized Configuration of the Aggregate System

The selected quartz sand has a maximum particle size of ≤0.6mm, fineness modulus of 1.8-2.2, and mud content of ≤0.3%; the grading is optimized through maximum density packing theory, reducing the aggregate void ratio to below 20%. In the Wuhan Han Show Theater project, this precise grading ensured tight particle arrangement, forming a rigid skeleton.

Innovation in the Fiber Reinforcement System

Copper-plated steel fibers (tensile strength ≥2850MPa) with an aspect ratio of 60-80 are used at 2-3% by volume; surface treatment improves the bond between fibers and matrix; fibers of different scales work synergistically to effectively prevent crack propagation. This reinforcement system achieves flexural strength of 18-25MPa.

Precise Regulation with Chemical Admixtures

Polycarboxylate superplasticizer with a water reduction rate ≥35% ensures workability at low water-binder ratios; defoamers control air content at ≤2%; retarding components adjust setting time. Qinglong's customized admixtures achieve an initial fluidity of 700-800mm.

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