I have previously done about 10 fillings without any problems, using Weber EXM 702. Perfect results every time. My local building supplies store switched from Weber's products to Finja's this spring, so I used Finja expanding concrete Fine. An HEA140 support beam that was filled at both ends. Filled up with expanding concrete and everything looked good. Covered the exposed area with plastic, then kept it moist. The pouring was done on Saturday and yesterday when I took a closer look, I suspected things had "gone wrong." Did an early form removal and surely there were some curses from me. What happened is that the expanding concrete "shrank"... I have about 1-2 mm distance from the expanding concrete to the steel beam... on both pours... My first thought was that it wasn't sealed properly and that there was a leak, but I couldn't find anything and that it happened the same way on both sites... Arrr. I should mention that I filled up with expanding concrete 10 mm above the underside of the steel beam and carefully stirred to ensure there were no air pockets.
Has anyone experienced anything similar? And what could cause this? I'll have to tackle it tonight after work, have considered several different solutions but the only one I keep coming back to is trying to break out the mess and recast (it won't be fun to knock it out but I probably don't have many options).
