Stack or layer the pour?

[sive]

First off I am really impressed with all of the input from this Forum.

This time my question involves dealing with the pour as it begins to harden long before I am finished. I am mixing my own, filling the 5-1/2x6 foot sections. Should I spread the early pours to the far reaches first, leaving room for 2 inches or so once I get the entire area covered to that depth? I will be covering the sections with plastic after each mixer full pour, but I am concerned that the area where the first pours are may start to get hard before I can get more on top of it. I was told to try filling up the far 1/2 of the section, screed it and then work on the section closer to the mixer.

M.Sive

[Rich]

That's a good method of pouring.. far then close. If you lay down 2" and it begins curing before you get the next pour on top of it you'll have a layered cold seam. A typical cold seam is vertical through the cross section of the slab - this isn't good but it'll just crack there first much like a control joint. When you have it in a layer it'll end up cracking the concrete everywhere there is a bump in the first slab.

[RobBase]

sive, even at 5.5' x 6' x 4", you're only talking about less than 1/2 yard of concrete. Most mixers can make that up in 2 batches or less. At 10-15 minutes per batch, you should be able to mix enough up for 1 panel without any cold joints. You really don't want any joints in a panel especially because your redwood dividers are your control joints.

Some things to help........cover the subbase/gravel with poly sheeting to help slow the dissipation of the mix water. Also, spread your first batch all over the area of the panel and use it to hold your wire mesh up half the thickness of the slab where it's supposed to be. Dump your second batch on top and jab and poke it all over so the two batches mix together.

Do your best to fill up the panel in 15 minutes or less and you'll have good results.

[Tom R]

Both Rich and Rob always give absolutely 'expert' concrete advice, and then some. But aside from all these 'technical' details, how about just buying a case of beer and getting a 'buddy' to mix batches at the same time you do. Just remember to 'water' down the beer so you don't get a 'staggered' finish! :D

[RobBase]

Thanks Tom R, but if I was a true "expert", I would not have neglected to offer the "beer and a buddy" advice. :D