We caught up with Tony Jones, Technical Director at The Concrete Centre, to find out more about the benefits of using precast concrete and its important role in the wider offsite construction sector.
Q: For those unfamiliar, can you give a bit of background to MPA The Concrete Centre and what it provides for those operating in the offsite sector?
Tony Jones (TJ): The Concrete Centre is part of the Mineral Products Association (MPA), that means that it is funded by the UK cement, concrete and aggregates sector. The sector invests in The Concrete Centre so that it can provide guidance and resources to enable specifiers and constructors to design and use concrete. These resources include online webinars, design tools such as Concept, and RC Spreadsheets, together with a wealth of best practice guidance, all available online. The resources of The Concrete Centre are relevant to all types of concrete as well as all those using concrete – whether the construction method uses cast in situ concrete, or offsite, factory produced solutions, or even hybrids of the two.
The Concrete Centre also champions innovation in concrete and the sustainable use of concrete, whether that is material efficient design, or using low carbon concrete. With the support our roduct expert colleagues across MPA we are also able to provide designers with updates on the decarbonisation of cement and highlight the excellent work and progress of our members, including those in MPA Precast.
Q: Where do precast concrete products provide specifiers with the most flexibility and range of options – structural products, cladding and facades or via volumetric modular units?
TJ: Whilst volumetric precast systems and volumetric systems that are partly concrete exist, the maximum flexibility comes from designs that combine precast elements, as that gives the designer more options to meet the design brief. Manufacturers can either provide the product elements, or guidance on a system approach for certain building types. They can also provide bespoke solutions that can be developed for just one project, or for a client’s whole project portfolio. Often the most efficient solutions incorporate both standard and bespoke products. For example, standard precast floor planks are used with a variety of construction systems. They can be paired with precast concrete frame solutions or precast wall panels and bespoke precast concrete cladding to give the desired aesthetic. Precast solutions are therefore able to accommodate virtually any practical structural layout and through the treatment of the façade provide limitless opportunities for the external aesthetic.
Q: What benefits does precast concrete have compared to competing materials such as light gauge steel frame or engineered timber?
TJ: Precast concrete is non combustible and does not need fire protection. This means that in the event of a fire the structure does not contribute additional fuel to the fire and is not reliant on following trades to achieve either its fire resistance or its fire separation function. This means that fires in concrete buildings generally cause less damage. Whilst the performance of concrete in fire is well documented in codes, standards and legislation, as an industry it is important to continue to review the state of the art. With this in mind, MPA Precast commissioned a full-scale test on a precast concrete cladding panel system by the Fire Protection Association and has demonstrated the fire performance benefits of this form of cladding.Concrete is also tolerant of water. Therefore, any water used to extinguish a fire, persistent leaks or accidental flooding in a precast concrete building is unlikely to cause any structural concerns. Precast concrete can also be used in combination with timber and steel, where there are advantages of using an optimised hybrid solution. Concrete ultimately provides superior structural and occupant safety, as well as providing a durable structure that can deliver the best whole life carbon outcome.
Q: Decarbonisation is hugely important across the construction industry generally – how is the precast concrete sector addressing the many issues surrounding the circular economy, embodied carbon and overall sustainability? Is net zero concrete possible?
TJ: The UK concrete industry was one of the first construction product sectors to introduce a sustainability strategy in 2008 and continues to report annually on a wide range of sustainability metrics.Early action since 1990 has seen the absolute carbon emissions of the sector have reduced by 53% - meaning we have been decarbonising faster than the UK economy as a whole. The UK concrete and cement sector has a detailed and viable roadmap setting out how it will achieve net zero by 2050. The industry also has the potential to go beyond net zero to become net negative when factoring in elements including the effects of carbonation, where concrete absorbs carbon dioxide from the atmosphere. MPA Precast also report on the precast and masonry sector’s performance annually and provide their members with annual sustainability audits. This ensures that all the sustainability principles identified in the strategy are sufficiently understood and addressed. Since 2010, our members’ factory carbon emissions and waste to landfill have dropped by 50% and 66% respectively. The use of supplementary cementitious materials (SCMs) has risen by a third in just two years (from 2019 to 2021).
Many precast concrete manufacturers are introducing new low carbon mixes to their products and investing in renewable and low carbon energy solutions within their factories. We’re under no illusion about the scale of the net zero challenge for both our and the entire construction industry, but it is possible. It will require further investment and innovation, not only by precast manufacturers and their supply chains, but also by government through the introduction of the infrastructure to enable a net zero economy. To demonstrate the sustainability of precast concrete and to promote best practice across the sector, The Concrete Centre and other MPA groups have worked with One Click LCA on customised templates, based on the One Click LCA tool, to generate Environmental Product Declarations (EPDs) for a number of precast concrete products. One Click LCA is one of the most widely used Life Cycle Assessment and carbon assessment tools by the construction industry in Europe and is already used by many engineering consultants and architectural practices in the UK.The templates developed are robust and comprehensive and were supported by an extensive list of hundreds of background datasets and EPDs, including MPA’s own latest cement EPDs. This would ensure that any concrete product EPDs generated by the new templates are as representative, accurate and comprehensive as possible. The tool has been externally verified by an Eco-Platform member EPD scheme, the International EPD® System, earlier this year.
Q: How do you see the offsite and precast concrete sector developing over the next 18 months? Any technical advances that will have an impact such as the revision to Eurocode 2?
TJ: The precast concrete sector continues to develop its concrete technology using the benefits of factory production and control to implement lower carbon and material efficient solutions. Currently the standard for the specification of concrete is being updated. This will give further options with regards to the use of lower carbon mixes including multi-component cements using limestone, GGBS and/or fly ash to increase the percentages of SCM within a concrete mix. There is more research underway to demonstrate the performance of calcined clays as an SCM, and even recycled concrete fines. Cement technologies and concrete mix designs will continue to evolve to achieve lower carbon concretes, and to use available constituent materials. Eurocode 2 is being revised, this will, for the first time allow durability performance to be demonstrated through testing. This approach is particularly attractive to precast concrete as the materials sources are well known and the factory control can ensure a high level of precision. The revision to the Eurocode will also cover the use of steel fibres, which should enable material savings in some applications.
For more information visit:
www.sustainableconcrete.org.uk
