Lendlease wanted to find a new ingredient to help reduce the carbon footprint of its cement mix.
Replacement materials for Portland cement frequently use slag cement and fly ash — byproducts of steel production and coal-fired power generation, respectively, so instead Lendlease pivoted elsewhere for a plentiful substance: recycled glass.
“We know that there’s a lot of glass available because, unfortunately, the U.S. is not fantastic about recycling glass through municipal recycling,” said Amanda Kaminsky, director of sustainable construction for Lendlease’s Americas portfolio.
For its 1 Java Street project in Brooklyn, New York — a 834-unit residential development that broke ground in April — Lendlease replaced 40% of the foundation concrete’s Portland cement with ground glass pozzolan.
The material not only lowers the embodied carbon of the concrete, it also utilizes waste from municipal glass recycling programs, which don’t always have an end market, according to Lendlease. In addition, the ground glass product is less permeable than cement made with slag or fly ash mixes, the company says.
When finished, Lendlease claims 1 Java Street will be fully electric and become New York state’s largest geothermal residential building.
Here, Kaminsky talks with Construction Dive about the 1 Java Street project and efforts to make projects more sustainable in the future.
The following has been edited for brevity and clarity.
CONSTRUCTION DIVE: What is your biggest takeaway from the 1 Java Street project?
AMANDA KAMINSKY: I think making sure that you engage with the supplier, structural engineer and subcontractor early on to ensure there’s buy-in from everybody involved. Also, testing [the concrete] before we decide on the final mixes.
It’s just a matter of choosing your partners carefully and thinking ahead to what the marketplace is going to look like five years down the road, seven years down the road, 10 years down the road. Are there steps that we can be taking right now to prime ourselves and the industry for that?
You teed me up for my next question. What does five, seven, 10 years down the road look like to you?
There are a lot more innovations coming into play. One of the reasons we’re focused where we’re focused right now is because these are materials that are available right now. But I do think there’s going to be options that enable us to even more fully decarbonize, and we will become more efficient with the materials that we’re purchasing.
We have our work cut out for us right now too, it can’t just be the manufacturers like working in their laboratories and factories. We have to be hyper collaborative with them right now.