An interesting article in the September Issue of ProLandscaper magazine, discussed the feasibility for the industry to move away from using cement. 2023 RHS Chelsea, featured low-carbon products (Cemfree) in both the Savills Garden designed by Mark Gregory, as well as the Horatio’s Garden designed by Harris Bugg Studio’s. Cemfree’s presence at RHS Chelsea Flower Show marked a significant step towards a greener future in the world of garden design, but the crucial question is to whether or not the industry adopts their example.
The problem with cement is in the calcination production process. Quarried rock is crushed and put into a cement kiln (with other materials) and heated up to around 1480°C to produce ‘clinker’. Once cooled, clinker is ground, and then mixed with gypsum and limestone. The issue lies in the heating of the clinker to extreme temperatures where considerable gas and intensive energy is used, and responsible for the considerable CO2 emissions. Alternatives, such as Cemfree don’t go through this process, but are alkali- activated meaning that it uses various activators to replicate cement – saving a reported 85% of embodied carbon.
Cemfree is viable environmentally friendly option, but comes with a 40% higher price tag. That will change if usage becomes mainstream, but currently those costs will need to be absorbed somehow. According to the article, Liz Nicholson of Nicholson’s Nurseries in Oxfordshire has taken the brave step to use only products that are free from Ordinary Portland Cement (OPC), absorb the costs and accept lower profit margins. An unusual, but impressive business model.
There are many hurdles to jump, especially as cement free alternatives are yet to be listed by British standards, which may cause reluctance on the part of contractors to use them. Cement, being cheaper, easier to work with, known to all and faster to work with, is still an alluring option and may deter swift adoption in the near future.