Cal. Pub. Res. Code § 42701

(a) In purchasing any materials to be used in paving or paving subbase for use by the Department of Transportation and any other state agencies that provide construction and repair services, the State Procurement Officer shall contract for those items that utilize recycled materials in paving materials and base, subbase, and pervious backfill materials, unless the Director of Transportation determines that the use of the materials is not cost effective. In determining the cost-effectiveness of the materials subject to this section, the factors that the director shall consider include both of the following:
1. (1) The lifespan and durability of the pavement containing the materials.
2. (2) The maintenance cost of the pavement containing the materials.
(b) This section also applies to any person who contracts with the Department of General Services or with any other state agency to provide these construction and repair services.
(c) The recycled materials shall include, but are not limited to, recycled asphalt, crushed concrete subbase, foundry slag, and paving materials utilizing crumb rubber from automobile tires, ash, and glass and glassy aggregates. The specifications shall be based on the standards of the Department of Transportation for recycled paving materials and for recycled base, subbase, and pervious backfill materials.