When we repave a street, we recycle all the material we take out of it. Nothing is sent to the landfill. Usually, asphalt is taken to a facility to be “reground” for use in a future paving project. For example, the “hot mix” we use to pave streets has 20% recycled content. City crews also use recycled asphalt in a mix to repair road shoulders. Sometimes, recycled asphalt is used to build up the road base.
We are also using materials in our concrete that reduce the carbon footprint of our concrete. The materials are called fly ash and slag cement. 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 almost half and can actually make the concrete stronger. We have required 25% replacement of Portland cement with slag or fly ash in all our sidewalk projects.