Arizona State University’s new research facility has achieved LEED (Leadership in Energy & Environmental Design) platinum certification for including low-carbon concrete into their build.

Martin Marietta AZ, the leading supplier in construction aggregates and materials during this project, was quoted: “This project was a great opportunity for our team to further increase fly ash use in the pursuit of CO2 reduction for mix designs. As an example, through mix optimisation, we were able to reduce the CO2 of one mix design by 59kg CO2e per cubic yard, which equated to approximately 624,000 kg CO2e savings.”

Cement is carbon-intensive to produce, so reducing the amount of cement in the building’s concrete mix was an essential element in lowering the project’s embodied carbon footprint.

The team set out to utilise the post-consumer by-product, fly ash, to reduce the total amount of Portland cement in the building structure by at least 40%.

“If you can replace a high percentage of cement with a recycled material like fly ash, you can offset a significant amount of carbon” said McCarthy Building Companies Senior Project Manager Carlos Diaz.

The concrete also needed to be aesthetically pleasing, being used in Class A architecturally exposed columns, walls, stairs, and polished concrete floors.

Ready-mix producer Martin Marietta AZ, concrete contractor McCarthy Building Companies, and admixture supplier GCP worked closely together to identify the right concrete mix that could substantially reduce the amount of cement in the mix.

Martin Marietta AZ used fly ash along with WRDA 64® water reducer & ADVA® 195 superplasticizer from GCP.

Once they selected this mix, the team started batch trials to ensure it performed as structurally intended. Based on the success of those results, they finalised the mix and began the concrete pour.

“Using high fly ash mix design for the 6,000 PSI mix is beneficial as it reduces permeability to water and produces a densified product. GCP’s admixtures played a big part in the success of this mix design, as in help with water reduction by using WRDA 64 and increasing concrete workability by using ADVA 195” said Joel Lopez Martinez, Martin Marietta AZ quality control manager.