What is Post-Tensioned Concrete?

Engineered with Precision: Post-Tensioning for Today’s Structures

Interspan delivers world-class post-tensioning solutions for new structures, combining global expertise with deep local knowledge. Our integrated approach ensures your project benefits from enhanced efficiency, superior quality, and a commitment to sustainability from concept to completion. We don’t just supply a product; we provide a fully engineered solution managed by our expert in-house team.

More Than a Product: A Fully Engineered System

Post-tensioning is not a simple component; it is a sophisticated, engineered system where success depends on the seamless integration of three critical elements:

• Specialized Materials: The specific properties of the high-strength steel strands, anchorages, and ducts are fundamental. These components must be designed, tested, and supplied as a complete, integrated system—not as individual parts—to guarantee performance.
• Integrated Design: The structural design must be precisely tailored to the capabilities of these materials to maximize efficiency and safety.
• Expert Installation: The on-site execution by skilled installers is crucial to realizing the design’s intent and ensuring the system functions correctly.

The true efficiency of post-tensioning is unlocked only when these elements work in perfect harmony. Interspan provides this crucial holistic approach. By managing the design, the materials, and installation, we ensure every part of the system is optimized for a superior structural outcome.

Understanding Post-Tensioning: The Principle and Method

The Principle: What is Post-Tensioned Concrete?

Post-tensioned concrete can be defined as “pre-compressed” concrete. Before the structure begins its working life, a compressive stress is strategically introduced into areas where tensile (stretching) stresses will later develop under load. Since concrete is inherently strong in compression but weak in tension, this pre-compression effectively counteracts the future tensile forces, allowing the concrete to behave as if it had a significant tensile strength of its own.

The Method: How is it Applied?

The post-tensioning method is typically used in concrete that is cast on-site. Ducts or sheaths containing unstressed steel strands are positioned within the formwork before the concrete is poured. This combination of an anchor, duct, and strand is called a “tendon.” Once the concrete has gained sufficient strength, the tendons are hydraulically stressed (tensioned) with jacks and locked off by permanent anchorages, putting the concrete into a state of compression.

The Interspan Advantage: Certainty by Design, Quality in Construction

Choosing Interspan means partnering with a team dedicated to delivering optimal outcomes. Our process is built on a foundation of in-house control and uncompromising quality, giving you a distinct advantage in the market.

In-House Design & Engineering

Our team of design and project staff are your greatest asset. They develop innovative, efficient, and practical solutions tailored to your project’s specific needs, ensuring a seamless transition from engineering to on-site execution.

Uncompromising Quality Assurance

Quality is embedded in our culture. From material selection to the final stressing of tendons, our rigorous QA processes guarantee that every component and procedure meets the highest industry standards, ensuring structural integrity and long-term performance.

Sustainable & Efficient Construction

We help you reduce the embodied carbon of your project. Our post-tensioning designs lead to:

Thinner Slabs & Lighter Structures: Reducing concrete volume and overall dead loads.

Longer Spans: Increasing design flexibility and reducing the number of columns and foundations required.

Faster Construction Cycles: Allowing for earlier removal of formwork and accelerating your project timeline.