What Are the Raw Materials of UHPC? Core Components and Material Selection Standards Explained

The raw materials of UHPC consist of five core components: cementitious materials, aggregates, fibers, admixtures, and active mineral admixtures. Material selection must strictly follow the principles of “high performance, high compatibility, and high stability”; high-quality raw materials are the foundation for ensuring the strength and durability of UHPC. Drawing on 28 years of formula R&D experience, Qinglong analyzes the core raw materials and material selection standards.

1. Cementitious Materials: The Core Support of Strength and Durability

Cementitious materials determine the basic strength and stability of UHPC. Core components: low-alkali sulfoaluminate cement or portland cement, which must meet a strength grade of ≥52.5 and an alkali content of ≤0.6% to avoid corroding fibers; Qinglong uses custom-grade low-alkali cement to ensure compatibility with fibers. Material selection standards: cement must pass tests for fineness, setting time, and compressive strength, with fineness ≤45μm, initial setting time ≥4 hours, and final setting time ≤12 hours. Quality control: a batch sampling inspection system is adopted, and each batch of cement must be accompanied by a third-party testing report; Qinglong's raw material pass rate reaches 100%.

2. Aggregates: Key Guarantee of Density and Workability

Aggregates must feature high purity, high hardness, and optimized particle gradation. Core components: high-purity quartz sand with a particle size range of 0.15-1.2mm, divided into coarse, medium, and fine gradations to ensure tight particle packing. Material selection standards: quartz sand purity ≥99%, mud content ≤0.5%, and Mohs hardness ≥7 to prevent impurities from affecting strength. Special requirements: ordinary river sand and sea sand are prohibited; the salt content of sea sand causes corrosion. Qinglong processes aggregates from natural quartz ore, increasing density by 30%. Function: optimized particle gradation can reduce the water-binder ratio and improve the compressive strength and impermeability of UHPC.

3. Fibers: The Core Reinforcement for Tensile Strength and Toughness

Fibers are the key component that distinguishes UHPC from ordinary concrete. Core types: alkali-resistant glass fiber or stainless steel fiber, with lengths of 6-12mm and diameters of 10-20μm. Material selection standards: alkali-resistant glass fiber must have an alkali resistance retention rate of ≥90% and a tensile strength of ≥1500MPa; stainless steel fiber must meet corrosion resistance standards, with a dosage of 2%-3%. Qinglong uses imported alkali-resistant fibers, which disperse well with no agglomeration. Function: fibers form a three-dimensional support network that solves the weak tensile resistance of ordinary concrete, giving UHPC a flexural strength of 20-35MPa and 5-8 times greater toughness.

4. Admixtures and Active Mineral Admixtures: Key Components for Performance Optimization

Admixtures and mineral admixtures improve the workability and durability of UHPC. Admixtures: high-efficiency polycarboxylate superplasticizer with a water reduction rate of ≥30%, controlling the water-binder ratio at 0.16-0.22 to ensure flowability; retarders and air-entraining agents are added as needed to suit different construction environments. Active mineral admixtures: silica fume and ultra-fine mineral powder, with a dosage of ≥30%; silica fume with a specific surface area of ≥15000m²/kg fills internal pores and improves density. In Qinglong's patented formula, admixtures and mineral admixtures work synergistically, enabling UHPC to reach an impermeability grade of P20 or above and withstand ≥500 freeze-thaw cycles. Material selection requirements: admixtures must be well compatible with cement and fibers, and mineral admixtures must have a purity of ≥95% to avoid introducing impurities.