PCI, the Precast/Prestressed Concrete Institute, is the technical institute for structural and architectural precast and prestressed concrete: things like beams, girders, double-tees, wall panels, and other engineered building components.
PCI publishes design handbooks and quality-control manuals, and runs a plant certification program that many projects require. Where NPCA is the common reference for underground and utility precast, PCI is the reference most often cited for structural and architectural work. Both underpin the QC practices a well-run plant follows.