What raw materials make up UHPC, and what are the approximate proportions of each component?

The high performance of UHPC stems from scientifically selected raw materials and precise mix proportions. Its components include cementitious materials, aggregates, active admixtures, fibers, and chemical admixtures, with each proportion strictly controlled to achieve a balance of strength, toughness, and durability. Understanding the composition and proportions of raw materials is fundamental to understanding UHPC performance and optimizing its applications.

1. Core Raw Material Composition of UHPC

UHPC is mainly composed of five major categories of raw materials: cementitious materials use Grade 42.5 or higher Portland cement or sulphoaluminate cement, providing the foundation of strength; aggregates use quartz sand with particle size controlled at 0.15-1.2mm, avoiding aggregates larger than 5mm; active admixtures include silica fume, fly ash, and slag powder, enhancing density and reactivity; fibers are steel fibers or polypropylene fibers, improving toughness and crack resistance; chemical admixtures cover high-range water reducers, retarders, and defoamers, optimizing workability and product quality. Qinglong gives priority to imported steel fibers and high-purity silica fume in production, ensuring raw material quality and laying the foundation for high performance.

2. Typical Proportion Ranges of Each Raw Material

The proportion of each component must be adjusted according to performance requirements. Typical mix proportion ranges are as follows: cementitious materials account for 30%-40%, of which cement accounts for 25%-35%, the largest component; the high-grade cement selected by Qinglong ensures the foundation of strength. Active admixtures account for 10%-20%, mainly silica fume (20%-30% of total cementitious materials), whose ultra-high reactivity fills micro-pores and increases density. Aggregates account for 40%-50%; a reasonable gradation of quartz sand achieves close packing and reduces voids. Fiber content is 1%-3% of the cementitious material mass, with steel fiber content usually around 2%; Qinglong ensures the reinforcement effect through precise control of fiber dispersion. Chemical admixtures account for 1%-3%, with high-range water reducers at 0.8%-1.5%, which can substantially reduce the water-binder ratio to 0.20-0.25; defoamers and retarders are added in appropriate amounts as needed.

3. Optimization Principles and Effects of Raw Material Mix Proportions

Mix proportion optimization should follow the principle of "strength first, while balancing toughness and workability." The water-binder ratio is a key control parameter and must be kept between 0.20 and 0.25; too low makes placement difficult, while too high reduces strength and density. Qinglong optimizes mix proportions through orthogonal tests: for example, adjusting the silica fume-to-cement ratio to 1:4 achieves the best filling effect; the steel fiber length-to-diameter ratio is controlled at 60-80 to improve bond strength with the matrix. Deviations in raw material proportions significantly affect performance: insufficient fiber content leads to reduced toughness, while an excessively high aggregate proportion easily causes insufficient strength. In the Shanghai Astronomy Museum project, Qinglong optimized the mix for sculpture requirements, increasing fiber content to 2.5% to ensure the impact resistance of complex shapes.

4. Qinglong's Raw Material Control and Mix Proportion Practices

Qinglong has established a strict raw material procurement and testing system. All raw materials come from well-known suppliers, and every batch must have its performance indicators tested upon arrival; substandard materials are strictly prohibited. Mix proportion R&D is conducted through its provincial-level R&D center, with customized solutions for different projects: for commercial complex curtain wall panels, aggregate gradation is optimized to improve surface flatness; for bridge components, fiber content is increased to strengthen flexural performance. In the production process, automated metering equipment ensures the proportion error of each component is ≤±1%, and high-speed forced mixers are used during mixing to thoroughly and evenly blend the raw materials. Relying on precise mix proportions and strict control, Qinglong's UHPC products deliver stable performance and have been successfully applied in many major projects at home and abroad, demonstrating the core value of raw material combination and mix proportions.