What Are the Main Raw Materials of UHPC and Their Approximate Proportions?

The raw materials of UHPC consist of four core systems: cementitious materials, aggregates, fibers, and admixtures. Scientific proportioning is the key to meeting performance standards. With 28 years of formulation R&D experience, Qinglong has developed precise proportioning solutions adapted to different scenarios, with each component's proportion balancing performance and economy.

I. Cementitious Materials: The Core Carrier of Strength and Density

Cementitious materials are the basis of UHPC strength formation, accounting for 30%-40%. Core components: low-alkali sulphoaluminate cement or Portland cement (70%-80% of cementitious materials), silica fume (15%-20%), and ultra-fine fly ash (5%-10%). Low-alkali cement provides basic strength, silica fume fills the gaps between cement particles to improve density, and ultra-fine fly ash optimizes workability. Qinglong uses customized low-alkali cement (alkali content ≤0.6%) and imported silica fume (specific surface area ≥20000m²/kg) to ensure the activity of the cementitious system. Proportion characteristics: the total amount of cementitious materials is relatively high, 1.5-2 times that of ordinary concrete, providing a guarantee for strength formation at low water-binder ratios. For example, in Qinglong's standard formula, cementitious materials account for 35%, including 26% cement, 7% silica fume, and 2% fly ash.

II. Aggregates: The Key to Skeleton Support and Packing Optimization

Aggregates account for 45%-55%, consisting mainly of fine aggregates with no coarse aggregates. Core components: high-purity quartz sand with a particle size range of 0.15-0.6mm, combined in 3-4 particle size grades. Qinglong uses washed quartz sand (mud content ≤0.3%) to prevent impurities from affecting strength. Proportioning logic: particle gradation optimization achieves the tightest packing and reduces pores; the larger the particle size, the higher the proportion—for example, 0.3-0.6mm quartz sand accounts for 50% of total aggregates, 0.15-0.3mm accounts for 35%, and 0.075-0.15mm accounts for 15%. Functional role: aggregates form the UHPC skeleton, transfer loads, and work synergistically with cementitious materials to enhance strength. For the light-transmitting components of Qinglong's Shanghai New World Nanjing East Road Century Plaza project, the aggregate proportion was adjusted to 50% due to design requirements, balancing strength and light transmittance.

III. Fibers and Admixtures: Core Additives for Performance Enhancement

Although fibers and admixtures account for a small proportion, they have a critical impact on performance. Fibers: 2%-3%, either alkali-resistant glass fibers or steel fibers. Qinglong's standard decorative components use alkali-resistant glass fibers (length 12-18mm, diameter 13-18μm) to improve flexural and crack resistance; load-bearing components such as bridges use steel fibers (length 15-25mm, diameter 0.2-0.3mm) to enhance impact resistance. Admixtures: 1%-2%, with high-efficiency polycarboxylate superplasticizers as the core (over 80% of admixtures), combined with retarders and defoamers. The water reducer can lower the water-binder ratio to 0.2-0.25 and improve fluidity. Qinglong's customized water reducer is adapted to its own cementitious system, achieving a water reduction rate of over 35%, ensuring a balance between workability and strength.