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Thursday, June 30, 2022

Sustainable aggregate

 

Gareth Moores, MD at Lytag Ltd, discusses how using lightweight aggregate concrete can help to meet sustainability targets, while also providing time and cost efficiencies 

 

The issue of improving sustainability credentials has risen to the top of the property and construction industries?? agendas and architects have a key role to play in finding cost effective and time efficient ways of incorporating sustainability into projects, without compromising the quality of design.  

 

There are quick wins that can help. One tried and tested approach is the use of high quality lightweight aggregate (LWA) in concrete, which can reduce the weight of the concrete in a structure while maintaining its structural strength. This can help improve the sustainability credentials of a project, while also enabling greater design flexibility and allowing cost savings.

 

Lightweight concrete 

A recent report commissioned by Lytag Ltd identified the potential savings that can be secured by using concrete made with LYTAG LWA in 6 storey and 30 storey buildings, with both a steel and concrete frame.

 

The report shows significant savings can be made in both building types and with both frame types. For example, in the high rise steel frame design, floors cast in LYTAG Lightweight Concrete can reduce the volume of concrete required in the foundations by 18%. It can reduce the volume of steel required by 7.5% in the steel framework, and 25% in the foundation reinforcements.  Significant savings can also be made through a reduced need for piling and minimising pile diameter and frequency. So what do these savings mean for architects?

 

Firstly, the cost savings to be passed on to the client can be significant ?? not least through the reduction in piling.  In addition, the lighter concrete and reduced dead loads can allow a greater flexibility in terms of design, such as larger structures, greater spans and a reduced number and width of columns.

 

The Shard provides a good example where, on the floors dedicated to offices, it is important that usable space has been maximised, in part by limiting the need for supporting pillars and walls.  

 

The composite floors were constructed using a steel frame and corrugated metal topped with the lightweight concrete using LYTAG LWA. The dead load of the floors was decreased, reducing the number of columns needed, and helping to deliver the desired open office spaces.

 

A sustainable option

For many architects, environmental considerations are also at the top of the agenda. Using concrete made with this LWA can help here too, both through the weight savings and because of the provenance of the aggregate. 

 

Manufactured from Pulverised Fuel Ash (PFA), a by-product of coal fuelled power stations, this material reduces the need for quarried aggregate and diverts PFA from landfill. A tried-and-tested material, it has been used in iconic and environmentally impressive projects including the Shard, Heathrow T5 and West Thames College.  

 

The environmental benefits of the material are exemplified by Bradford University??s Sustainable Enterprise Building. Meeting the requirements for a BREEAM ??Outstanding?? rating was an important aim of the design. Concrete made with LYTAG LWA was used in the floors of the building, reducing the dead load. This allowed a sustainable timber frame to be incorporated, with the use of LYTAG LWA contributing towards the BREEAM rating. 

 

To get the best results from concrete made with LWA, architects should speak with their supplier from the earliest stage of design in order for the building to secure the maximum design, cost and environmental advantages.

 

Sustainability is a key requirement of all new build projects today, and Government targets to reduce the environmental impact of the built environment show that this trend is set to continue. With reliable ??quick wins?? widely available, it is now up to architects to make sure that they are taking full advantage

 

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