There are 3 ways to bend a 2 x 4.
I made a bridge with a curved top.The bridge has a curved 2 x 4 x 8' hand railing.
The hope is that the boards will bend easier.They are treated with pressure.I don't know if I'll be able to bend along the bridge top with the clamps.
The lumber is soaked in a water-based preservative that makes it "pressure treated".You will be well into retirement before soaking in water.Some folks use steam on thin strips of wood, but not lumber. If it's going to take more than one 8' board, how will the transition be handled? Some curved boards are created by making multiple partial parallel saw cuts.Most of the lumber is pine which will warp and twist as it dries.I wouldn't build a curve on the bridge.After it has dried a bit, build it against a form and install it.Don't install it if it turns out to be crooked.
Does the great room need a 4'x4' end table if I style them in a U?
The 96" board is a little more than 1/3 of the way around.Attach vertical stakes around the perimeter of your circle with a sheet of plywood.You can bend the board by making saw cuts that allow you to remain in contact with the stakes.You can use a 2x4 that is already dry to figure out how many and how deep each saw cut needs to be.Glue on the back side of the board when it is dry to help it retain its shape.
I haven't tried this myself, but I have seen on a few very high end decks that curved wooden handrails are typically laminated, in other words you will need to rip your stock into whatever thickness it will bend at, maybe 1/2 " or 6mm, and then lay them over theThe method was prescribed to me by the designers of those rails.If you use a form with adequate plot points, you'll be able to get a radius instead of the other way around.
If the stock isn't long enough a simple scarf joint is made but you never stack the scarfs, you overlap them for strength.
I'm afraid that the handrail will be neither strong nor appealing with your method.
The back cuts to bend the board will need to be most of the way through to the front surface, so do you suggest filling them in with some material after the rail is at it's desired form and in place?I have never seen this method of board bending used in a concrete form.I don't understand how gluing the backside will help the board retain it's shape unless the glue is adhering the rail to something, but over the long run mechanical fasteners will probably be a better choice because of the minimal surface area to be glue at the points of attachment.The large area being glued relative to the thickness will not be a problem.
You can make a form from scrap plywood or particle sawn if you want, but you have to look through the 2x12 or 2X10 lumber for the ones that will give you the most straight grain knot free strips.
The radious is about 50 and it will take 1 8 ft board.I'm not sure what that means.It's weird to work with, it is long lasting if applied correctly.Lots of draw backs...