Caltrans encourages recycling of concrete.In a recent memo to contractors, Caltrans encourages the use of returned plastic concrete. Returned plastic concrete is concrete that is still in a fresh and useable state and can be recycled for further use. The memo specifically mentions sidewalks, driveways, and drainage pipe covers as suitable applications. The Caltrans memo, "Contractor Option to Use Returned Plastic Concrete" points out that up to 15% returned plastic concrete can be used. The specification is found in Section 90-9 of the 2015 Revised Standard Specifications.
The specification was the result of an intensive work effort between members of CalCIMA's Technical Committee, ready mixed concrete operators, and Caltrans. It was developed in order to find options for use of returned plastic concrete besides disposal in a landfill. An accompanying report, Environmental Impacts of Recycled Plastic Concrete, found that for every yard of returned plastic concrete that can be re-used, there is a 15.3% reduction on carbon footprint and 16.2% percent reduction in embodied energy. The report concluded, "The reuse of fresh, returned plastic concrete offers the opportunity to directly reuse the water, cement, and aggregate used in the production of concrete."