They are doing auger pressure grout piles in other words they drill a hole into the ground to a predetermined depth and as they withdraw the auger they pump grout (cement mixture) into the hole. Once that’s fully pumped with grout they install the rebar cage to give it rigidity and strength. Berkel and Company is the subcontractor hired to do the work. Auger Pressure Grouted Piles | Berkel & Company Contractors, Inc.
I'm amazed they can put the cage in after its been poured. It must be a really thin grout.