Post-Tensioned Concrete for Sustainable Design, Part I

January 12, 2024

At Odeh Engineers and WSP, we’ve made a commitment to a more sustainable and resilient future through our Future Ready® initiative, and our participation in the SE2050 Challenge. In this, the first of two blog entries, we explore how we are reducing the embodied carbon impact of concrete structures by using post-tensioned concrete structural solutions.

What is Post-Tensioned Concrete?

Concrete structures rely on reinforcement to provide the system with its full capacity. Traditionally, non-prestressed reinforcement (RC) has been utilized. However, by replacing the non-prestressed reinforcement with prestressed reinforcement, such as post-tensioned cables, we can significantly enhance the performance of the system while reducing the overall material usage.

In post-tensioned (PT) concrete structures, workers strategically position high-strength cables, known as tendons, before pouring the concrete. Once the concrete has hardened, hydraulic jacks are employed to stretch the tendons and secure them in place. This process effectively compresses the concrete, reducing tension and improving its strength. Additionally, if the tendons are draped, they tend to straighten, generating an upward force that counteracts the applied design loads.

Advantages of Post-Tensioned Concrete

PT slabs and beams can typically span longer distances with less material and less thickness than RC structures. For many buildings, this delivers significant construction advantages, including:

  • Buildings can be shorter, and basements can be shallower, with fewer columns, creating more open space in floor layouts.

  • PT slabs are usually flat, making it easier to arrange mechanical systems.

  • Precompression provides improved crack control and water tightness, reducing the need for maintenance and increasing the lifespan of structures.

In addition to reducing construction materials, PT solutions can also provide indirect sustainability and cost advantages. For example, reduced depth of basements leads to shallower support of excavation, less soil to be removed, and fewer trucks hauling soil away from the site. Shorter buildings also equate to reductions in vertical transportation systems, exterior cladding and interior finishes. With less material handling and shorter construction times, the embodied carbon savings and cost savings can add up quickly.

Future innovations, such as substitute cementitious materials and carbon sequestration, promise to deliver even more sustainability advantages.

Odeh Engineers offers a variety of Post-Tensioning related services from design through construction inspections. Our team is eager to help you determine if post-tensioning is the right solution for your next project!

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