We're going to be placing two 60-foot-high concrete structures with a footprint that's 17x24 feet. They're to be placed in dewatered navigation locks and we have only 10 days to form and pour the concrete. The mix is very lean because engineers are concerned about heat buildup caused by cement hydration. We only need to hit 2500-psi compressive strength in 90 days. We'll be doing the pour when air temperatures are 30 to 40 F. We'll be using jump forms, but I'm concerned about form pressures and allowable stripping times. Because of the limited time, we need to make the lift height 20 feet. What kind of system should we use for forms this high? And when will the concrete be strong enough to support the anchorages used for the jump forming system?
You need to get help from your form manufacturer or from a forming consultant. With cold weather and a lean mix, form pressures will be high and you may have to design for pressures produced by a full liquid head of concrete. Lifts 20 feet high will require some pretty stout forms and bracing. You also may need some early-strength test results to decide when to strip the forms and when the concrete will be strong enough to support jump form anchorages. Get engineering help for these problems.