It is really encouraging to see the amount of innovation that has been activated by the climate and biodiversity crisis. The latter will be a key theme of my next post, but here are some of the key innovations that I believe will help to tackle the decarbonisation aspect of the challenges we face in the construction industry:
- Recycled cements - Not all cement is hydrated and activated during concrete production, so recovering concrete waste more carefully and re-separating constituents may allow us to recover cement for re-use. Whilst this will require additional energy, cost and new equipment, the upcycling benefits would help to reduce new clinker production, which is the ultimate requirement for decarbonisation. If you do have to demolish, its really important to look into the viability of cement recovery.
- Calcined clays and high filler blends - these will help to reduce portland cement use in the short term and replace GGBS and Fly ash in the longer terms as these products become unavailable (due to decreases in primary steel production and the use of coal respectively). Waste heat recovery and the abundancy of calcined clays and limestone fines helps to make this commercially viable and low carbon. In addition, high filler cement blends seem to help mitigate the 'overshoot' problem associated with early striking for programme gains leading to concretes that achieve a higher ultimate strength then required (and thus wastefully use cement).
- It was interesting to hear from Holcim that they don't see any viable future for AACMs which have been pushed quite heavily in certain places as a zero carbon solution. The alkali activators have a higher carbon footprint than Portland cement, and compared to GGBS, much more alkali activators are required to be compatible with clays which would be the future primary SCM for this technology.
- Digital Tools - There is a huge opportunity for digital tools to help decarbonisation, for example using sensors in concrete pours and through using feedback loops to optimise mixes. At the moment this seems to be used mainly to aid programme times (striking can be done as soon as the sensor provides information that concrete has reached sufficient strength), but the same technology could be used for cement/ reinforcement reductions which we should push for.
- Digital tagging -? This is at very early stages, but could involve inserting chips into concrete mixes to create an in-situ digital material passport which can be accessed by scanning the concrete. This creates an exciting opportunity to aid future re-use and retention and also engage the public in the materials in our buildings. Perhaps with more thinking (not currently being developed), reclamation for re-use elsewhere could also be aided using these chips if a methodology for different end of life cases are thought about in initial design and information stored on the chip.
- Graphene - This is an incredibly complex material only invented 20 years ago, with multiple types and methods of production, which all ultimately impact the potential use in concrete. What has been found is that certain graphene nanotechnologies (in combination with certain cements) provide strength and durability benefits to concrete, which could (through careful design) lead to reductions in concrete quantities and rebar requirements. Lightly reinforced slabs such as grade slabs and metal decks seem like good potential uses.? But there are a number of obstacles to overcome, not least the even distribution of this nanomaterial into the mixes to ensure we don't end up with weak spots in the concrete.
- The European Trading System impact - By 2035 Holcim anticipate that CCUS will be cheaper than the taxes they would have to otherwise pay through ETS carbon taxes. Whilst I still think the industry is over-reliant on CCUS in their decarbonisation plans (~36%), its great that the ETS is pushing the concrete industry to decarbonise more broadly. This will push up the cost of concrete unless efficient solutions are found, which would in turn promote material reduction and material substitution which I think we need for a regenerative future .
- 3d Printing - I can't decide if this will provide benefits or if it's just cool. In theory, more complex and optimised geometries can be formed with this technology which could reduce material use. But the mix composition, minimum thicknesses and issues with reinforcing create several obstacles that may prevent any actual benefits from being realised. If it does take off, I'll at least be able to claim being one of the first to create something using the 3D printing concrete 'ink' (as pictured).
- My final positive outcome was the collaboration and passion from others in the group, the energy and knowledge of the staff at HIC - particularly Madhura Joshi Let’s connect for hosting us, and for Nick Powell ILM7 for facilitating engagement which is crucial in accelerating this journey.?
