by MacAlpine

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Multi-strand -tensioning

Post-tensioning and Sustainable Construction Practices

As the global construction industry evolves, the pressing need to balance building efficiency with environmental sustainability has never been more urgent. 

Post-tensioning concrete slabs stands out as a technique that aligns with sustainable construction practices when compared to standard reinforced slabs. 

The Post-tensioning Method

Post-tensioning is a technique used in concrete construction that involves applying tension to tendons after the concrete has been castThis compresses the concrete and allows it to support more weight and span greater distances. This method strengthens the concrete, making it more efficient and durable.

Reducing Material Usage

One of the primary environmental benefits of post-tensioning is the reduction in materials used, particularly concrete and steel. 

Post-tensioning allows for slimmer slab construction compared to traditional reinforced concrete, so buildings and other structures require less concrete and steel to achieve the equivalent or improved performance. By minimizing the use of these materials, post-tensioning reduces the overall carbon footprint of manufacturing and transporting these materials.

Energy Efficiency in Buildings

Post-tensioned slabs can also contribute to energy efficiency in buildings. The ability to create larger, open-plan spaces without intermediate columns makes it easier to design buildings that make better use of natural light, reducing the need for artificial lighting. 

Moreover, they capitalise on concrete’s thermal mass properties, which absorb and retain heat, thereby minimising the energy demands for heating and cooling—a major component of energy consumption in buildings.

Lowering Transportation Costs and Emissions

The ability to use less material reduces the direct environmental impact of the materials themselves and the cost of transportation. 

Fewer materials mean fewer truckloads are required for transportation to the construction site, lowers fuel consumption, and reduces greenhouse gas emissions associated with transportation.

The environmental advantages of post-tensioning in concrete construction are significant, aligning well with sustainable development goals. 

By using fewer resources, enhancing the durability of structures, and improving energy efficiency, post-tensioning not only meets the demands of modern construction but does so in a more environmentally friendly manner. 

Case Study – Millers Quay, Merseyside UK

Interspan’s approach converted the 275mm thick reinforced concrete slabs to 250mm thick post-tensioned slabs. This strategic choice resulted in savings in reinforcement tonnes and concrete volume, leading to an impressive reduction in upfront carbon dioxide (CO2) emissions.

The numbers speak volumes:

The total reduction in CO2 emissions across the expansive 37,375m2 scope of the project equated to an astounding 1,250T.

To put this into perspective, this is equivalent to the carbon emissions from more than 1,450 flights between London and New York or the CO2 output of over 400 average family cars over an entire year.

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Interspan Solid, Stable, Sustainable

The environmental advantages of post-tensioning in concrete construction are significant, aligning well with sustainable development goals. 

By using fewer resources, enhancing the durability of structures, and improving energy efficiency, post-tensioning not only meets the demands of modern construction but does so in a more environmentally friendly manner. 

Interspan was created as an alternative to conventional post-tensioning companies. It focuses on providing an integrated design, manufacturing, and construction service rather than just a post-tensioning supply company for building projects.

Our core focus is designing and delivering superior post-tensioning systems and engineering solutions. We provide technical consultancy and support for the full range of works from initial design to complex, detailed dynamic analysis, construction engineering, and on-site activities.

Our commitment to continual improvement and innovation provides our clients with leading-edge technology and best industry practices. 

The results are cost-effective, reliable, and efficient post-tensioned and reinforced concrete construction engineering solutions.

REASONS TO USE POST-TENSIONED CONCRETE FOR CONSTUCTION

Longer Spans

Post-tensioning allows longer spans to be used. This means the number of columns per floor is reduced, which opens up the floor area and increases the flexibility of the structure.

Overall Structural Cost

Post-tensioning becomes more economical than plain reinforced concrete slabs for spans greater than 7 metres. This is due to the reduced cost of materials, labour and formwork.

Reduced Floor to Floor height

The slab thicknesses can be reduced when using post-tensioning. This results in savings for facade costs and allows more floors to be constructed within the original building envelope.

Deflection Free Slabs

Slab deflections can be eliminated with post-tensioning.

Rapid Construction

Post-tensioning allows for earlier removal of formwork and reduced back-propping requirements. This means faster construction cycles and quick formwork reuse.

Column and Footing Design

Reducing the slab thickness has the benefit of reducing the floor dead loads, which results in an economical design of the concrete columns and footings.

Waterproof Slabs

Post-tensioned slabs can be designed to be 100% crack free, which means the slabs are essentially waterproof. In order to construct a waterproof slab, the choice of concrete mix, curing methods, quality workmanship, and detailing are key factors.