I work at a camp center in the Alps in France and we teach beginner climbers on one of the building's concrete walls. Until now we've used the iron beams as anchors (using a redundant sling set-up) for toproping, which is safe and works well, but it takes 40 minutes to rig. We are looking at drilling anchors in the bomber reinforced concrete and were wondering which set-up to go for? Do we use rap-chain with rings, gym double clips, pitons with cable hangers?
Most climbing bolts, with the exception of Fixe and Petzl, were actually designed for use in concrete rather than rock. Options are nearly unlimited, but since the loss of a student or two would be counterproductive, let's go with the really bomber anchors.
Hilti, in my experience, makes the best bolts for concrete. Now, don't fret, I know you are in France and the French and the Germans have been going at it for close to a hundred years, but while Hilti sounds Teutonic, they are in Liechtenstein, a German-speaking principality that like Switzerland has preferred to keep their noses to the grindstone and let the other folks murder each other while they reap the rewards. In short, they make great bolts.
The bolt you want is the HSL-3-GM 10/20. This bolt is much like the Rawl (Powers) 5-piece, but better made and has a nut on one end so you can replace the bolt hanger and other gear as needed. Get the 15 mm (roughly .59-inch) by 115 mm (4.5 inches). I've used a ton of these bolts, and will personally vouch for them.
A couple of pointers. Use a new, sharp bit so you get a nice hole that is within the tolerance of the bolt. As you drill (with a power drill), note whether you suddenly encounter formidable resistance -- concrete is almost always reinforced with rebar or other bits of steel and you won't be able to drill through it with a carbide-tipped bit. If you think you have hit steel, give up and move to a different anchor location. As always, use a piece of aquarium tubing to blow out the drill dust, then tap in the bolt and tighten. Use two bolts per anchor and set the bolts about eight inches apart. For the hardware, I recommend the Fixe V-Anchor with Draco carabiners. This all-steel rig costs about $90, but will last just about forever, and has reversed carabiners to prevent the rope from unclipping itself. If you are on a budget, you can make a lesser-quality though still plenty strong anchor by using steel quick links and chain, available here in the U.S. at any hardware store, though in France they might require a permit. Next!