Cold Joint

There are epoxy compounds for this situation, but this incidence should be covered in your specifications. If cold joints aren't allowed then you'll need engineering approval to proceed. If the raft (unfamiliar terminology) is a spread footer and was over excavated; then if I were the constructor; I would proceed with placement. Especially if I hadn't covered any rebar yet. If the raft is a pile cap for a pier I would take the same approach, but only after seeking engineering approval. If the raft is above grade (beam cap on a pier or bent) I would propose the the use of epoxy to the Engineer of Record.

Your production is suffering, but to proceed without engineering approval could cost more time, and hence money in materials and labor.

If you want to keep your crew working without delay, demo the 300mm (1 ft.) of concrete and start over. This time with a standby pump. Which brings up another topic: if it wasn't your pump, the pump operator should be responsible for all the costs of delay and/or rework.