Expected to start August 2nd is Phase II of the Airport Way paving project, making the stretch between Royal Brougham and Dearborn just as gorgeous as the newly completed section from South Spokane Street to South Dearborn. There’s a new green twist, however. Phase II is breaking ground into new territory as the first SDOT paving project to offer an incentive for contractors to green up the concrete process. The request for proposals asks bidders to use a new concrete specification with increased pozzolans (no not Mazatlan – that would be a fun incentive). The incentive is more money (also fun) if the contractor can use more pozzolans, which reduce the carbon footprint of our concrete.
Pozzolans are slag cement or fly ash; they are by products from the manufacture of steel; and the flue gas of coal-fired electric power plants. They are waste products that would otherwise be land-filled if there were not an alternative use for them. Replacing Portland cement with slag reduces the greenhouse gas emissions of concrete by half and can actually make the concrete stronger. However it does take a bit longer to dry. That said, we’ll soon know what the contractor decides to do in response to the new specification and if it helps us meet our carbon footprint reduction goal (look for more details in a follow-up story!).