What Are the Advantages of Unbonded Prestressed Steel Strands?

Unbonded prestressed steel strand is a core specialty material in modern construction projects. It is widely used in critical structures such as bridges, high-rise buildings, and subways, providing stable support and offering significant advantages in construction efficiency and durability. As a seasoned manufacturer specializing in the production and supply of unbonded prestressed steel strand, we understand the crucial impact of material quality on project safety, efficiency, and cost. 

Choosing high-quality unbonded prestressed steel strand is more than just selecting a building material; it provides a multi-layered defense for project quality and safety. The following provides a detailed introduction from multiple perspectives.

I. Basic Structure

- Diameter Specifications: Common diameters include 12.7mm, 15.2mm, 15.7mm, and 17.8mm. 15.2mm is the most common diameter in construction projects, suitable for most common structural requirements.

- Core Load-Bearing Body: Composed of multiple high-strength steel wires twisted together, the core structure features a seven-wire structure (six side wires surrounding a central wire), primarily made of high-strength low-alloy steel. This section offers excellent tensile strength, with standard products reaching 1860 MPa and custom designs exceeding 2000 MPa, ensuring the structure resists deformation under long-term loads.

- Anti-corrosion Grease: This specialized grease, applied to the exterior of the steel strand, performs a dual function. It provides excellent lubricity, ensuring smooth tensioning operations and minimizing construction losses. It also isolates the strand from moisture and oxygen, preventing rust and aging, significantly extending the life of the structure. It's particularly suitable for outdoor or underground projects exposed to humid, salt-fog environments.

- Protective sheath: Usually made of high-density polyethylene (HDPE), it is resistant to cold, heat, abrasion, and UV rays. It protects against damage during construction and later from environmental corrosion, fully protecting the internal steel strands and anti-corrosion grease from mechanical damage, chemical corrosion, and environmental influences.

Ⅱ. Working Principle

1.Simplified Construction Process: Unlike traditional bonded prestressed products, workers can directly begin tensioning operations without the need for on-site grouting of holes. This reduces construction steps by approximately 30%, significantly shortening the construction period while also lowering labor and equipment costs.

2.Efficient Force Transfer: After tensioning, the strands are secured by anchors at both ends, allowing the prestressed force to be directly transferred to the building components. This pre-stresses the structure, instantly improving crack resistance and bearing capacity. Furthermore, the strands slide flexibly against the concrete, eliminating the need for bond strength to transfer stress. This ensures more uniform force distribution and facilitates subsequent maintenance.

III. Key Features

- Simple and Efficient Construction: Eliminates the complex steps required for bonded prestressing, such as pre-drilling, strand insertion, and grouting. This reduces construction steps, saves labor and time, and is particularly suitable for the rapid construction of cast-in-place concrete structures.

- Flexible and Adaptable Layout: Based on structural design requirements, the prestressing can be flexibly arranged in curved and broken-line configurations within the concrete member to accommodate various load conditions, such as bidirectional loads in long-span floor slabs.

- Excellent Corrosion Resistance: The three-layer protection system of "steel strand material properties + anti-corrosion grease + HDPE sheath" effectively resists external corrosion, extending the service life of the structure and making it highly adaptable to humid and corrosive environments.

- Stable Mechanical Properties: Featuring high strength (typical tensile strength of 1860 MPa, with some models exceeding 2000 MPa) and low relaxation, it maintains stable prestressing over time, ensuring structural safety and reliability.

- Customized production is supported: Our professional technical team can provide customized services for special requirements such as special diameters, higher strength grades, and specific sheath colors. Mass production can be achieved within 15 days, precisely matching various special project requirements.

IV. Application Areas

Unbonded prestressed steel strands are suitable for a wide range of applications, making them a versatile material in construction projects. Specific applications include the following:

- Bridge Construction: Providing uniform tension to long-span beams, reducing cracks, improving bridge stability and durability, and extending service life.

- High-rise Buildings: Used for prestressed reinforcement of floor slabs and walls, enhancing overall structural strength, helping to withstand external shocks such as earthquakes, and improving seismic performance.

- Underground Projects: In underground projects such as subways and utility corridors, their excellent corrosion resistance allows them to withstand humid underground environments and ensure long-term structural safety.

- Other Applications: From small factory reinforcement to large-scale venue construction, customized production allows for adjustable diameters and strength grades to meet the precise needs of projects of varying sizes.

Unbonded prestressed steel strand is indispensable in modern civil engineering, offering significant advantages in increasing structural spans, reducing building weight, and enhancing durability. Produced in strict compliance with national standards, our unbonded prestressed steel strands offer reliable quality, efficient construction compatibility, and durability, helping projects achieve cost reduction, speed improvement, and safety. 

Please contact us with any inquiries, and we welcome you to visit our factory at any time to learn more about our production processes and comprehensive quality inspection system.