Hollow, monitored piles that can be reused and incorporate services.

Last updated: 4th February 2022

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Innovation Lead: Christine Coonick
Project number: 104797
UKRI funding: £614,357


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A collaboration of leading construction firms have reimagined foundations. Keltbray Piling, Converge, DB Group and Arup have turned passive, static piles that only load bear, into hollow and impression piles that offer greater value to a building throughout its lifecycle. HIPER Pile uses a hollow and impression pile design and light-weight cement-free concrete to provide the same shaft-bearing capacity with fewer piles or narrower piles. The pile incorporates smart technology to monitor performance and the void can be used to integrate renewable technologies. With up to 80% reduction in materials and emissions possible, and greater on-site productivity, HIPER Pile helps achieve carbon reduction and circular economy aims.

Innovation type: Digital, Energy, Manufacturing, Process
Organisation type: Construction tier 1 contractors, Manufacturer, Supply chain

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Project pioneers

Keltbray Piling is part of the Keltbray Group which has been supplying specialist services to the UK construction industry for more than 40 years, not least through its involvement in high-profile projects such as HS2 and the redevelopment of Battersea Power Station. Driven by a decade of technical and construction experience, Keltbray Piling has a vision to develop a range of innovative pile foundations that are more than just highly efficient structural components, but incorporate carbon-saving elements and turn foundations into fully functional, valuable long-term assets.

The problem

Bored piling mechanical methods have seen very little development since their introduction after the Second World War - where deep cores are drilled and filed with concrete. In redevelopments, typically time is now spent coring through existing piles only to replace them with larger or deeper piles which is time consuming and resource intensive. Underground spaces in developed inner cities are heavily congested with transport networks, services and foundations, and we are fast running out of usable space. If piles could be reused, or are optimised to use less concrete, savings could be made on cost, time and emissions when building national infrastructure.


HIPER Pile offers groundbreaking technological advancements in deep foundations that will revolutionise the productivity of large-scale construction programmes, and make foundations a smart component in the life of the building. Bored piles no longer just deliver dumb foundations with a single load-bearing function. HIPER Pile has the potential to incorporate offsite manufactured components, increase the shaft-bearing capacity, while using significantly less material and reducing embodied and construction-related carbon emissions. It enhances the whole-life cycle of a building by offering better use of space and the ability to reuse piles at the end of building life. They can also enable integration of renewable technologies that enhance building use.

Key Insight

Keltbray Piling has an ambition to radically change how the industry regards deep foundations and bored piling, as well as a desire to increase delivery of value-engineered solutions to its clients and hold a competitive edge in the market. The Transforming Construction programme offered the chance to accelerate innovation in the area and fitted well with the needs of a product platform approach to buildings.

First step

A key moment came in October 2018 when Keltbray signed a collaborative agreement with City, University of London to develop commercial and technical solutions for the hollow pile, that could create unprecedented efficiencies in the design and construction of deep foundations. The collaboration was supported by the Knowledge Transfer Partnership (funded by Innovate UK) which allowed Keltbray to gain new skills and access to the latest academic advances in science and technology in order to deliver this specific and strategic innovation project. Keltbray Piling also engaged the services of Arup Geotechnics to critique the trial data as they went, and assist in ensuring each element of the HIPER Pile was well-reviewed and fit for purpose.


Currently bored piling offers little to the whole-life value of a building. Pouring concrete is a quick, cheap solution but comes with high material cost and emissions impact as well as creating problems at end of life. Using sensors to monitor piles means performance and re-use can be assured. The hollow design offers further benefits in emissions savings and the potential to integrate systems that provide value to the building through its life.

Process innovation

HIPER Pile stands for Hollow, Impression-enhanced, Precast, Energy-generating and Re-useable piles. It's a completely new approach to bored piling that pairs re-designed piles with improved processes and smart technology. The innovation uses hollow and impression pile designs and light-weight cement-free concrete to provide the same shaft-bearing capacity while using fewer piles or piles with a reduced diameter. This reduces the material needed but it also dramatically increases the rate of production on site per day by 20-50%. Further advancements are in progress to develop a prefabricated solution, which will improve quality control and mitigate the risk of non-conformances, further speeding up construction on site. Using HIPER Pile on large-scale construction will have a huge impact on carbon-reductions in bored piling. The void through the pile means less material is used. Plus it uses an ultra-low-carbon cement-free alternative to concrete which will reduce carbon emissions involved in its manufacture, transport and use by as much as 80% - a significant contribution to Net Zero targets.

Digital Innovation

Sensors embedded within the HIPER Pile continually record and transmit live data relating to strength gain and will soon also include strain, tilt and relative humidity capabilities.

Whole life innovation

Keltbray Piling were determined to be able to assess the performance on the deep piles during the life of the build, but also to see if they could be reused for future developments. To do this, the team embedded wireless monitoring that would record long-term data. Thanks to the smart monitoring of its performance, designers can assess the performance of the piles and decide whether they can be uses again in other builds. And the pile void could be used for a range of functions with the potential to integrate as part of a future energy system. The space in the pile could be used, for example, for generating and storing geothermal energy, for batteries to store electricity, or for storing water - making the purpose of foundations more than just load-bearing but offering significant social, economic and environmental benefits in the short and long-term.


Development of HIPER Pile required significant collaboration across R&D and the supply chain. The civil engineering department at City, University of London holds the patent for the hollow pile concept and were involved in testing and further optimising the impression pile design. Keltbray tasked Converge, experts in concrete sensors and wireless, cloud-based technologies, to develop the smart technology that would be embedded in the pile. DB Group developed Cemfree, an ultra-low-carbon cement-free alternative to concrete that can reduce carbon emissions associated with its manufacture, transport and installation by up to 80%. Other collaborators included Arup's Geotechnics who have monitored and peer reviewed progress ensuring the final product stands up to technical scrutiny and is accepted and specified by the market; G-Core who design and commission geothermal heat exchangers; Mayflower Engineering Ltd. who designed a bespoke piece of apparatus crucial for constructing full scale HIPER Piles; and Socotec Laboratories who have been involved throughout, carrying out maintained load tests on HIPER Piles and conducting independent material tests on both conventional OPC and Cemfree concrete mixes.

  • Active Building Centre
  • Arup
  • Converge
  • DB Group
  • Mayflower Engineering
  • Socotec Laboratories

Lead support

The Transforming Construction Challenge team has supported the project to help identify and connect the HIPER Pile team with new potential sites to trial the technologies. The team also linked Keltbray up to research capabilities at Loughborough University for 3D concrete printing of future variations of a pre-cast HIPER Pile, and the Active Building Centre who are trialling the latest energy generating and storage innovations to support the UK’s shift towards renewable energy.
Keltbray has also joined the Infrastructure Industry Innovation Partnership (i3P), an independent innovation community open to major infrastructure projects and construction clients and their supply chains, providing them with the opportunity to disseminate the results of the HIPER Pile project and gain much valued feedback from potential clients.

Long Term Vision

The HIPER Pile project is bringing pioneering developments in deep foundations, with wide-ranging benefits that are driving notable changes in UK construction and beyond, helping us improve the performance of materials, reduce carbon emissions, monitor performance during the life of the building, and even go as far as reuse foundations for future buildings. The longer term vision is to integrate HIPER Pile technology within hybrid environmental control systems that combine ground source heat pumps and geothermal systems with rain water collection and renewable energy generation as part of an active building - transitioning from individual buildings to a harmonious district scale thermal energy model.

Human Stories

The HIPER Pile combines precast components to make the shift towards off-site manufacturing. This reduces the people, processes and traffic on site, mitigating the risk to the health, safety and welfare of staff.
The product also incorporates capacity to generate and store renewable thermal energy; reducing reliance on national grid infrastructure and also takes a positive step towards sourcing and using green energy. Wider adoption of this technology at scale will support the move towards cleaner energy, reducing the likelihood of developing health issues related to air pollution and fuel poverty.

Powerful Processes

As part of the research project Keltbray Piling had an ambitious testing and demonstration schedule, engaging existing clients to obtain space on live construction sites to support prototyping trials around the installation and testing processes of the various technologies. This allowed the team to trial each step of the innovation - from optimising the impression forms, refining the concrete mix designed for early strength gain, and testing and revising the wireless sensor monitoring technology. Each set of trials brought about a new iteration of the approach and technical capabilities, delivering continuous performance improvement and an evidence base of data that could be independently interrogated by Arup.

Fascinating Facts

HIPER Pile reduces carbon emissions by as much as 80% due to the use of Cemfree (developed by DB Group) that is an ultra-low carbon, cement-free concrete. Due to the improved structural and geotechnical efficiencies of the HIPER Pile, smaller piles using less material can now provide the same bearing capacity, speeding up daily production rates by 20-50%. HIPER Pile provide a competitive engineering solution and enable the client to consider otherwise unachievable alternatives such as shorter more efficient piles. This means structures can be supported on fewer or reduced diameter HIPER Piles, which can reduce labour costs, by shortening construction programmes, and cut material usage by up to 70%.


Active Energy
In delivering this project, Keltbray has identified the huge potential HIPER Pile will have in integrating with building components that generate, manage and store energy as part of an active building. The team is forming a proof-of-concept around the HIPER Pile void providing a well-insulated thermal heat sink and offer a more thermally efficient method of storing heat than the ground (which is currently used in standard ground source heat pump systems). HIPER Piles will also play an important role in coordinating environmental control systems at building and district scales to support the journey to NetZero carbon.

To remove the risk in using these new materials and technology, Keltbray Piling needed to provide the assurances required for market acceptance. HIPER Pile are connected to Converge's patented wireless 'smart site' sensing networks providing live data capture. This gives the site teams improved monitoring of concrete strength gain and pile behaviour under load. It also gives future designers confidence that the piles have performed as expected and so can be reused in new developments.

HIPER Pile provides a competitive engineering solution and enables the client to consider otherwise unachievable alternatives such as shorter, more efficient piles. This means structures can be supported on fewer or reduced diameter HIPER Piles, cutting material usage and cost by up to 70%.

HIPER Pile can be constructed using Cemfree, a material developed by DB Group. Cemfree is an ultra-low-carbon, cement-free alternative to concrete. Field trials have shown that Cemfree can save as much as 80% of the carbon emissions involved in its manufacture, transport and use in construction. The void through the hollow pile can also be used for rainwater storage, backfilling with surplus soil or thermal energy generation which can be incorporated with a buildings heating and cooling system.
The added capability for the potential to reuse HIPER Pile in future builds is a massive step for the construction industry towards a circular economy; seeing these critical structural building components as having continued use beyond the life of the initial building.

The HIPER Pile combines precast components to make the shift towards off-site manufacturing. This enables faster delivery by reducing the number of processes and people on site and decrease the frequency of vehicle movements, such as concrete wagons. This all contributes towards a safer, better-controlled construction site, mitigating the risk to the health and safety of staff.

Due to the improved structural efficiency of the HIPER Pile, smaller piles are now able to provide the same capacity, speeding up daily production rates by 20-50%, reducing construction programme timescales and streamlining the handover process to other contracting teams.

Whole-life Value
Re-using deep piled foundations can deliver greater sustainable outcomes, cost and time savings. Through the integration of sensors, 'smart' piles can deliver performance data providing the assurance required by future developers and insurers to re-use existing piles. And the huge carbon reductions realised by using Cemfree (80%), means that the bored piling sector can play a significant role in helping construction meet net zero targets.