Which is the most effective compaction system for placing large amounts of PI clays per day with scrapers: Cat 815F/Ks, towed weighted sheep feet behind tractors, or impact rollers behind a tractor?
I’d say you should look to an 825 if placing large volumes of fill.
As long as we have the room we run a 825. In tight places like keyways we use a ride on sheeps foot.
I have placed fill behind 631's many times with both an 815 and an 825. Depending on how many yards a day you are putting down and the condition of the clay, that will determine what works best. An 815 can never get the compaction you need if the fill is nasty and there are a lot of loads per hour. An 825 has enough size and horsepower it can eliminate the need of a dozer on the fill if you have one on it. We seldom used 815's on scraper fills. They were used mostly on truck fills.