Archive for category: Building News

_{Image: UK Hempcrete}

It really doesn’t look like much, but hempcrete is the green building material that’s got eco-savvy homeowners and architects excited by its potential to be a sustainable alternative to environmentally expensive bricks and concrete.

It is made using a carefully calibrated mixture of hemp shiv – the dried inner core of the hemp plant – mixed with lime and water.

But although hempcrete seems like a very modern building material, it has a history stretching back over 1,500 years.

Hemp plaster from the sixth century still lines the walls of the UNESCO-designated Ellora Caves in India, and hemp mortar has been discovered in ancient Merovingian bridge abutments in France – which is fitting, as France was at the forefront of the 1980s drive to modernise hempcrete and introduce it to a new generation.

Back then, wet hempcrete was cast onsite, as concrete is today, but the challenge of getting the mixture right made it a tricky product for laypeople to use. Too much of any of the three ingredients could make the material runny and weak, while not enough could cause crumbling.

Its drying time also posed problems. In fair conditions, cast hempcrete can take between four and six weeks to cure. But a cold damp winter could slow the process to at least six months, restricting its mass use across northern Europe.

Impeccable environmental credentials

Despite the challenges, hempcrete’s undeniable environmental credentials have meant it was a case of when, rather than if, it would muscle its way into the mainstream building trade.

Image: UKHempcrete

Liam Donohoe, chief operating officer at UK Hempcrete – a Derbyshire-based company designing and supplying materials to building projects using hempcrete – tells Euronews Culture that sustainability plays a part in every area of the product’s development.

“Hemp, unlike conventional crops, doesn’t require a lot of fertilisers or pesticides to protect it as it grows. The type of fibrous hemp usually used in construction is a tall plant that grows quickly and so can be cropped and planted quite close together, naturally suppressing weeds,” he says.

“I’m not saying it takes no energy to produce hempcrete, it does. But when you compare it to man-made insulation and wall infills, it has an unlimited life span and the primary ingredient is a renewable crop that costs a lot less energy and carbon to produce.”

Research and development changed everything

Experiments in France and at Belgium’s University of Leuven in the early 2000s saw researchers begin tackling the barriers preventing hempcrete from realising its full potential as a mainstream building product.

The eureka moment was the development of the hempcrete block or ‘green brick’, which took the specialist skill and guesswork out of using the material.

The lightweight fibrous block opened up a new world of possibilities for the material without diminishing any of its eco-credentials. It is free from volatile organic compounds (VOC) and indefinitely retains its acoustic, moisture absorption and thermal conductivity properties – in sharp contrast to synthetic insulation that decompresses over time to become less effective.

It is now a consistent, lightweight and reliable product that can be easily transported to sites and used by jobbing builders without extensive training.

Hempcrete versus concrete

Despite its versatility, experts are quick to dismiss comparisons between hempcrete and concrete. Concrete is a reinforced, structural building material that can support its own weight, while hempcrete is used around a frame of wood, steel or concrete. Think of it as insulation that doesn’t cost the Earth.

“When hempcrete is made into blocks, it’s strong enough to support itself, so can be used to build multi-storey buildings. There are a number of examples in the Netherlands, South Africa and France, so it’s not that you can’t build high or strong structures with it, but you need to use it around a frame,” Donohoe says.

“Researchers are working on developing a structural application for hempcrete, but that currently means usually tweaking the recipe. The sweet spot is finding something that’s very consistent, that goes onto the building site just like any other building product, without compromising too much on the carbon inputs to the recipe by using ingredients that are less sustainably produced.”

Hempcrete’s time has come

Europe is setting the pace in hempcrete use

Image: IsoHemp

The major players in the hempcrete world hail from Europe. In the Netherlands, France, Belgium, Germany and Italy, hempcrete is routinely used to retrofit old buildings and form the core of new builds.

One of the biggest producers is Belgian company Isohemp. The Fernelmont-based business has been trading since 2011 and operates in five countries.

It produces more than a million hempcrete blocks a year and claims that the projects it has worked on have saved 18,000 tonnes of C02 from the environment – that’s equivalent to the emissions produced by a patrol car circumnavigating the planet 32,000 times.

Although the UK is a few steps behind the pack, the gap is closing fast. UK Hempcrete knows of 300 to 400 houses in the UK that have been built with hempcrete and sees a bright future for the product.

“The future of hempcrete will be in prefabrication using modular methods of construction. We already have timber-framed houses largely assembled in factories, brought to the site and constructed there. There’s no reason why hempcrete houses can’t be similarly prefabricated,” Donohue says.

“In Britain, companies are building conventional family homes with hempcrete that look just like estate homes anywhere in the country, but with vastly superior eco-performance benefits.

“A focus for us is retrofitting pre-1940s housing stock. We are working with community housing cooperatives around the country who have old houses that are cold and leaky. The biggest opportunity is developing that market alongside the growing newbuild market.”

But perhaps the full potential of hemp and hempcrete has yet to be realised. BMW currently use a weight-saving hemp polymer in the door panels of its i3 electric car, while in southern Italian earthquake zones hempcrete is used as a flexible building material that can cope with Earth movement, rather than rigid, brittle concrete.

The future of hempcrete as a green building material looks assured. But with researchers working on ever more innovative ways to use it, perhaps we’ve only seen a tantalising glimpse of the difference it can make.

Source: The Phoenix Newspaper

Railways from France, Hungary, the USA, South Korea and elsewhere have expressed interest in the prototype Adaptable Bridge & Lift System. This modular stainless steel footbridge is designed to improve the passenger experience and exploit the latest industrial techniques to lower the environmental impact of production and maintenance and provide opportunities for British manufacturing.

The bridge aims to be ‘simpler, better and greener’ than current designs, according to Hazel Needham, Associate Structural Engineer at Expedition Engineering.

Infrastructure manager Network Rail currently installs about 20 new or replacement footbridges a year, according to Professional Head of Buildings & Architecture Anthony Dewar who has been investigating ways to increase this output. He told Rail Business UK that the modular design developed by the AVA consortium offers the possibility of higher production volumes and a new approach to procurement, with modules prebuilt and stored ready for use.

Construction could begin as soon as a contract is awarded, with an estimated total site time of 15 weeks of which installation would require a 36 h track possession; it is hoped that this can be reduced to 27 h. The target is an overall footbridge project timescale of 20 months from contract award to handover.

‘We anticipate a robust demand pipeline that leverages AVA’s design and construction principles, capitalising on manufacturing efficiencies through batch procurement, economies of scale, and incremental enhancements’, said Eva MacNamara, director of Expedition Engineering.

Seeking fresh ideas

The origins of AVA lie in a Footbridge Design Ideas Competition which Network Rail organised through the Royal Institute of British. Architects in 2018 in an effort to attract some fresh ideas.

Dewar said some existing bridges offer a poor passenger experience, and there has been little innovation in footbridge procurement, design or construction until now.

Network Rail felt there was the potential to further develop the design which had been selected as the runner up in the competition. This led to a spin-off project to produce a prototype which has now been erected on an industrial site at Sittingbourne in Kent.

Modular elements

The AVA bridge is designed to offer an ‘elegant and timeless’ design and to be suitable for ‘any station anywhere’, said Bob Atherton of steel supplier Outokumpu.

The modular approach reduces the time needed on site, ensures quality, is adaptable and provides economies of scale. ‘It should be straightforward to adapt the bridge for the vast majority of station configurations’, said Dewar.

The visible parts of the bridge are the actual structure, not cladding, with the main span being assembled from standard modules made from Forta LDX 2101 high strength duplex stainless steel plates. The steel is produced by Outokumpu using low carbon electricity, and processed by its UK subsidiary in Sheffield. According to Atherton, it has double the strength of typical stainless steel, enabling the thickness to be reduced without impacting on performance and meaning smaller foundations are required.

The steel is suitable for most locations in the UK, but a higher grade such as Forta DX 2205 with higher corrosion resistance could be used in more corrosive coastal or polluted environments.

The sheet steel is laser cut and folded to shape using ‘Industry 4·0’ manufacturing processes which are now well established outside the rail sector. The steel has inherent durability without needing painting, a bead-blasted permanent anti-glare treatment and is graffiti resistant.

The 1 200 mm long modules are joined together to form a maximum span of up to 20 m, with symmetrical custom length modules at each end of the span to provide the precise length required. The stairs are similarly modular, with the span above the landing modified to provide the required height.

The bridge is bolted together with using pre-loaded bolts supplied by Bumax which will not loosen over time. Assembly does not require specialist skills, and this approach simplifies maintenance; the bridge could even be dismantled and relocated if desired.

The walking surface is aluminium, which has a 25-year warranty and 60+ year design life with the ability to be easily replaced.

Network Rail is particularly keen to ensure that all critical parts of the structure are visible or easily accessible for inspection and maintenance. There is integrated lighting, and internal cable routes with hinged access panels.

Options include a roof, not fitted to the prototype, and privacy screens if there is a need to prevent users seeing over the side of the bridge.

The consortium expects the bridge to offer lower capital and whole-life costs than the current generation of footbridges, and even greater benefits over the full life cycle. A traditional bridge needs periodic painting, but there is always a temptation to delay this into the next budgeting period, meaning major work is required when the job is eventually tackled and ultimately leading to a shorter overall life.

The AVA bridge has an expected life of at least 120 years, requiring minimal maintenance which can be undertaken without requiring a track possession. ‘What you see today is what it will look like in 100 years’, said Atherton.

Accesibility

The AVA bridge is intended for use at stations, where passengers increasingly expect the provision of lifts for accessibility. However, it could be built without lifts.

The lift shafts are modular units, assembled off-site by ARX and delivered complete and ready for erection. This has reduced installation time from 26 weeks to 2 weeks.

The lifts draw on experience from the industrial lift sector. Features for reliability included two motors for redundancy, and a single section door. The motors are housed at platform level, rather than on top of the structure, facilitating simpler maintenance.

There are two layout options for the lifts. The narrow variant has the lifts in line with the stairs, and is suitable for locations with restricted space on the platform. The preferred wide variant has the lifts alongside the stairs, which takes up more space but eliminates the need for a wheelchair user to change direction. The prototype has one lift of each type.

Because the lifts are separate modular structures, they could be added to an existing bridge of an alternative design; studies are underway for a potential installation at Seven Sisters.

Prototype

The prototype bridge is a ‘version 0·9’, according to the project partners. Changes have been made based on the experience gained during manufacturing and assembly, and would be incorporated into production bridges from new.

One example is the laminated glass, which is designed to provide a more open feel than high steel sides. The glass is it at a slight angle to reduce glare, but this proved complex to install, and a simplified way of achieving the correct angle was developed to reduce costs.

When Rail Business UK visited the prototype on a hot day, the sunlight reflecting from the floor was dazzling, but production bridges would have a different deck surface treatment.

The first production AVA bridge is scheduled to be installed at Stowmarket in May 2025.

Source: Railway Gazette

Forest of Dean-based engineering group Versarien enters into a contract with national not-for-profit organisation, Building For Humanity, to assist in a major project in Lancashire by providing £200,000 worth of 3D printing services.

A huge deal worth £200,000 has been struck between advanced materials engineering group Versarien and national not-for-profit CIC, Building For Humanity, to build a village of new homes for veterans and low-income families in Lancashire using 3D printing technology.

The Forest of Dean-based group will act as a ‘print partner’ for the charity’s flagship project in Accrington, providing a full service from design to construction.

46 ‘high-quality, affordable’ homes will be developed in the project, set in five blocks alongside a community hub led by Building For Humanity for residents to access its range of supportive resources — the building of the hub and the first block will make up phase one of the project, set to commence imminently now that the contract has been signed.

Versarien will provide support to Build For Humanity’s design team, to ensure alignment with its 3DCP printing parameters, before moving on to supply staff and printing services at the construction stage.

3D construction printing (3DCP) involves using 3D printing methods including extrusion, powder bonding and additive welding to fabricate buildings or construction parts.

The method is hailed for being more environmentally-friendly than traditional building practices, as it produces less waste, while also allowing for design flexibility — if successful and properly invested in, the UK could see 3DCP being used more and more in the construction industry as a sustainable alternative that could alleviate the current housing crisis.

CEO of Versarien, Dr Stephen Hodge, said:

‘This initiative is the first 3D printing housing construction project in the UK and one ideally suited to the services we can provide.

This project is a pivotal opportunity to showcase Versarien’s capabilities in enabling low-carbon, efficient construction solutions, exemplifying our commitment to innovation and sustainability.’

Source: SoGlos