Concrete

Concrete takes a lot of energy to produce and transport, making it one of the biggest sources of greenhouse gas emissions among building materials. To reduce its impact, builders can use recycled concrete aggregate or choose cemental alternatives like fly ash and slag, which need much less energy to produce.

Concrete also affects water flow. Porous pavement helps by letting water soak into the soil instead of running off. Options include pervious concrete, porous asphalt, pavers, and plastic grid systems. These surfaces reduce stormwater, recharge groundwater, and improve habitats in streams and rivers.

Washington State Department of Transportation -- Standard Specifications for Road, Bridge, and Municipal Construction

• Recycled materials are required under SHB 1695 (2016). Bidders must state the total percentage of construction aggregate and concrete materials in the project that are recycled. These percentages must follow the limits in Section 9-03.21(1)E, Table on Maximum Allowable Percent of Recycled Material.
• For recycled aggregates, projects must set goals and plans for reusing and recycling construction aggregates and recycled concrete materials (RCW 70A.205.700).
  
   

King County's Sustainable Purchasing Executive Policy (CON 7-22-EP)

• Lowering embodied greenhouse gas (GHG) emissions associated with a product’s manufacture, transportation and use
• Purchase of recyclable and/or recycled products

King County’s 2020 Strategic Climate Action Plan

• GHG 67. Reduce embodied carbon of materials used in King County capital projects

All agencies with capital programs are required to evaluate which capital programs and projects in their CIP use the largest volumes of high-embodied carbon materials such as concrete, asphalt, carpet, steel, gypsum, rebar, and wood and to identify which capital projects and programs will use lower embodied carbon contract specifications for the highest impact materials.