Opinions on Flatwork

[Anonymous]

I am currently in the process of preparing to do the flatwork for a 30'x40' metal building with a 30'x20' pad out front and was wondering if I should put a vapor barrier under my slabs. After my slabs are done, how long should I wait before walking on them, moving furniture (shelves, workbenches, etc.) on them, driving on them, and putting up a basketball goal pole with j-bolts embedded in a thickened area of the slab.

Thank you

[Rich]

You're going to get about 70-80% of your strength in 7 days or so. Full strength in 28 days - or you should anyway. Walking on them could be as quick as a few hours or as long as a day - it really depends on the mix and environmental factors. I've had slabs flash that we can walk on in a few hours of pouring and scrambling to get it finished. On the other hand I've had to wait for 24 hours before I could snap lines on it. These extreme cases are rare but do happen - flashing happens more than often than not. I would say you should be safe to walk on the following day and wait at least 7 days to drive on and put up the basketball hoop backboard.