Breaking new ground … Firth EcoMix® EC50
It’s common for people to upgrade their smart phones every year or two because technology is changing so fast ... and it’s not too different when it comes to the technology to decarbonise concrete … a space that market leader Firth is happy to be in and one that is constantly evolving.
So when it comes to reducing environmental impact and meeting aspirational project objectives, Firth will go to great lengths to work with those willing to push the boundaries – such as Jonathon Chan, Associate Principal for Landscape Architect Boffa Miskell.
“In the middle of last year, I was working on the landscape design for a sustainable new commercial complex for a well-known New Zealand brand,” says Jonathon. “When looking at the concrete paths for this new facility there were no specific sustainability landscape targets. However, at Boffa Miskell we work hard to produce designs that are environmentally sensitive, which involves reducing the carbon footprint through material selection.”
“For starters we actively tried to minimise the area of concrete required in the design, while maximising greenspace... and then I thought I would check to see what I could find online in the way of decarbonised concrete mixes, and I came across EcoMix® from Firth.
“I spoke to Bernice Cumming, the Architectural Consultant at Firth, and we looked at what was possible. I learned that the calculations for these mix designs are very complicated, and even need to take into account the type of sand used. I asked her if it was possible to attain EC50 — reducing the CO2 by around 50% — to achieve the best result for the project. Bernice took my request away and came back and said that EC50 was new for Firth, but they would like to do a test slab to assess the performance of the mix which, considering that the project hadn’t been awarded yet, was really something!”
Peter Robinson, Director from By Design Concrete says, “Bernice asked if I could pour a test panel of EC50 at our yard which I was happy to do. We poured a panel approximately 2.5m(W) x 8m(L) a 100mm (D) on 19 October with a light exposed finish. It was left for five days before we drove light vehicles over it and then after 28 days later we had our normal traffic use that area.”
Jonathon Chan (left) with Peter Robinson checking out the newly laid EC50 panel.
Five months later and Peter says that he is surprised, and happy, with the performance of the test panel. “There was no mesh used, there are also no expansion cuts ... and it has no cracks. We concrete guys are always very happy when there are no cracks in the concrete we lay.”
“You wouldn’t know that there was anything different about it. Our loader and trucks, which weights up to about seven tonnes, drive over it every day. This photo was taken in late February, and it still looks great … and it’s crack free.”
“Completing our first EC50 mix was breaking new ground for us at Firth but it’s good for designers and specifiers to know it is possible,” says Bernice. “Charles Mah, our Firth Technical Engineer, was pivotal in the development of the EC50 mix, the testing and performance to reach strength and 28 day performance requirements.”
“There are a lot of factors that come into the calculations. Elements such as 10% black oxide or 10% white pebble all have their own carbon numbers and can drop the overall EC calculation. We are happy to push the envelope and try new things because we’ll never progress if we don’t.”