Common Models and Specifications

The specification of a steel strand is usually denoted by "structural configuration + nominal diameter + strength grade."

1. Classification by Structural Configuration

*   1×7 Structure (Absolute Market Mainstream): Consists of 1 central wire and 6 outer wires twisted in a spiral. It accounts for over 90% of the market share, with nominal diameters typically ranging from 9.53mm to 21.60mm. Among them, 15.20mm (or 15.24mm) is the most universally used standard specification in domestic and international bridge and building construction.

*   1×3 Structure: Formed by twisting 3 wires in a triangular arrangement. It is commonly used in small prefabricated components, floor slabs, and foundation engineering, with typical diameters of 6.2mm, 8.6mm, and 10.8mm.

*   1×19 Structure: A multi-layer structure (e.g., 1+9+9) mainly used for large-diameter, high-load-bearing scenarios such as cable-stayed bridge cables and suspension bridge main cables. Common diameters include 17.80mm, 21.80mm, and 28.60mm.

2. Classification by Strength Grade

Tensile strength is the key indicator of load-bearing capacity. Currently, 1860MPa is the absolute mainstream grade in engineering. Other common grades include 1720MPa, 1770MPa, and 1960MPa. For super-large-span bridges or special engineering projects, high-strength grades can reach 2000MPa, 2200MPa, 2230MPa, and even 2360MPa.

3. Classification by Surface Treatment and Application

*   Bright (Uncoated) Steel Strand: The most common type, requiring post-grouting for anti-corrosion protection, suitable for general prestressed engineering.

*   Galvanized Steel Strand: Features a galvanized surface for extreme corrosion resistance, suitable for coastal, highly corrosive environments, or outdoor storage.

*   Unbonded Steel Strand: Coated with anti-corrosion grease or wax and wrapped in a High-Density Polyethylene (HDPE) sheath. It is highly convenient for construction and widely used in cast-in-place floor slabs, underground garage roofs, and foundation engineering.

*   Epoxy-Coated Steel Strand: Used in marine, nuclear power, and other special projects with extremely high requirements for corrosion and chloride ion resistance.

*   Indented/Compacted Steel Strand: The surface is altered to increase the grip strength with concrete or to make the structure denser, suitable for specific anchor gripping.

Specification Marking Example:

Taking "1×7-15.20-1860" as an example, it indicates that the steel strand has a 7-wire structure, a nominal diameter of 15.20mm, and a tensile strength grade of 1860MPa.