How Precast Discover Digital | Undergoing A Digital Revolution
Over the past couple of years, precast concrete has been quietly undergoing a digital revolution. Since the government mandated BIM on all major public projects in 2016, precast specialists have been investing in technology and training, and the sector is now one of the most advanced adopters of digital technology in the construction industry.
From complex architectural details, such as the façade of Techrete’s V&A Dundee, to structural cores, including Creagh’s new HSBC headquarters in Sheffield, and even modular housing kits like Sterling’s HexxHome – precast concrete firms are delivering services across a wide range of projects using BIM and digital technology. And they may have only scratched the surface of its potential.
“Precast is perfectly placed to exploit BIM,” says Matthew Butcher, environmental and technical officer at British Precast. “Precast firms are working in a controlled factory environment, which is ideal for the principles of design for manufacture and assembly.”
BIM software house Trimble, whose Tekla product was used on the V&A Dundee, agrees that there are exciting digital possibilities for the sector. “Our software has been developed with each precast construction stage in mind, from design and pre-construction through to when the building is erected on site,” says business manager, Ismail Makda.
“Digital construction can also facilitate the workflow between different stakeholders on one project. An architect can send their 3D model to the precast firm, who can create a highly detailed model with all the embeds, reinforcement, and so on, and at the same time, the engineer can use the model to assess the structural characteristics of the proposed building, such as wind loading.”
FP McCann became the first precast specialist to achieve BIM Level 2 accreditation with BSI, two years ago, and completed its first BIM Level 2 project last year, a warehouse job at the Daventry International Rail Freight Terminal (DIRFT). Senior technician Colin Mackenzie says the BSI accreditation helped formalise FP McCann’s internal processes.
“We have created clearly defined roles and responsibilities, as outlined in PAS 1192, to ensure project control,” he explains.
FP McCann has worked hard to implement BIM and it is starting to pay off. “The shift to working in a data rich 3D environment has created significant additional work, training people in new software and developing components with embedded data,” says Mackenzie. “Benefits have included clash detection, for example, on industrial schemes, allowing steel frame issues to be highlighted early.”
The company typically works with the architect’s 3D model, or on industrial projects the steel fabricator’s model, and Mackenzie saying federated models are rare.
“We generally work at LOD (level of detail) of 4 or 5,” he says. “More recently, we have started receiving received BEPs (BIM execution plans), where the LOD and LOI (level of information) have been specified for various project stages.”
On the DIRFT scheme, Mackenzie adapted Tekla’s software to speed up design of bespoke precast units, from the usual two hours to “just a couple of minutes”.
Mackenzie says FP McCann’s greatest gain from BIM adoption has been the parallel development of internal production processes.
“Using the embedded data in our Tekla software, we have been able to transfer information to lasers allowing quicker and easier mould set up,” he says. “Additional investment in data driven mesh/rebar machines, adopting simpler reinforcement configurations, will accelerate rebar cage fabrication. On box culverts, we’ve reduced cage fabrication time by 50-60%.”
The next step in FP McCann’s BIM transformation is coordination with logistics. “Software firm StruSoft has supplied us with their Impact system, which links with our modelling data, and allows our planners to assign units to casting beds in the factory and then link up with deliveries to site,” Mackenzie explains.
Meanwhile, Creagh is also seeing advantages from BIM adoption. Connor McMahon, project manager on the company’s digitally-driven Sheffield HSBC project, says the business has committed to implementing BIM across the business.
The firm uses Autodesk’s Navis Works and BIM 360 Glue to coordinate design and highlight clash detection, and McMahon says he has appreciated being able to “extract and share information from the model,
so we can work collaboratively with other design teams”.
“The increase in productivity we’ve seen has increased Creagh's trust in BIM,” McMahon explains. “We can work quicker, with more accuracy on cost build-up for estimates, reduced lead times, and improved timeframes during the critical path process.
“We are seeing better quality control, with a reduction in remakes and miss casts, plus we can be sure of ordering the exact quantities of cast-in components. BIM has promoted more sustainable and lean manufacturing processes internally.”
Creagh has also developed an internal BIM library, with details of standardised components, which “improves BIM authoring in the design process”, McMahon says.
To date, precast objects in the NBS National BIM Library have been mostly limited to infrastructure products, FP McCann, for instance, has uploaded pipes, rings and manhole covers.
However, Mackenzie says there is limited demand to extend the provision of standard components across other product groups.
He believes there needs to be more drive from clients for BIM to be fully implemented on projects. “We currently find that while there is intent, it is not necessarily followed through with full adoption,” Mackenzie explains.
“We have worked on three projects where the client wanted BIM Level 2 protocols, but the schemes did not end up being managed that way.”
Makda feels there is still “a lot of work to do to enable external stakeholders to collaborate more effectively through digital construction”. There is a culture of retaining certain information they consider sensitive, he says, but BIM is about “openness and transparency”.
However, he adds: “I have observed a leap in the use of our software and clients finally realising the long-promised benefits.” Makda feels most digital benefits to date have been at the preconstruction stage and thinks work onsite has so far been excluded. “There is great promise with new technologies like robotic total stations and virtual reality headsets,” he says.
Meanwhile, digital strategies in Westminster and among major clients would also seem to favour precast. “The government is prioritising use of offsite manufacturing, and now wants a ‘platforms’ system of standardised components, while major clients like Heathrow are also moving in this direction,” says Butcher. “Precast is a material and concept that can fulfil that vision."
“Consistency in construction methods and the subsequent cost savings is what is driving the Government’s policy on DfMA – and it presents a unique opportunity for the precast sector,” agrees Makda. “Standardised panels can be modelled and then stored indefinitely, ready to be used on buildings that have similar designs and layouts, high-rise buildings, schools and hospitals.”
From an environmental perspective, precast also has a BIM advantage. British Precast has already created Environmental Product Declarations (EPDs), with life cycle assessment data, for several product groups, and these are expected to be used more commonly once the BRE Green Guide is discontinued in the early 2020s.
“In future, designers will be able to call up EPD data from all products on a project using the BIM model, and obtain up-to-date environment assessments on those materials to inform the specification,” explains Butcher.
Meanwhile, British Precast is continuing to work with the Construction Products Association on Lexicon, the plan for a single data standard across all industry product categories.