Pea gravel or crushed rock?

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  #1  
Old 04-21-05, 03:20 AM
hermmona
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Pea gravel or crushed rock?

Hello! I am putting a concrete patio in our backyard. It will be approx. 21ft x 18ft. I have been told by 2 different people to use different materials for my base. Which is better, or does it matter? One guy told me to lay 5ins. of crushed rock w/dust and tamper it level to 4ins. deep. Another guy told me to lay 4ins. of pea gravel, level it, and not tamper it, because it didn't need it. Both then said to lay the concrete on top of the base.

So, does either one work better than the other? I have found that the pea gravel is much cheaper, so if it works just as well, then I'll go that route. But if crushed rock is better, then I have no problem with that either.

Also, can you tell me when should the forms be placed? Should I lay the base first, with it being outside the dimesions of my concrete pad, and then stake the forms on top of the base, using 2x4's? Or should I use 2x8's and lay the base inside the forms along with the concrete? I do plan on putting rebar mesh on top of the base before pouring the concrete for reinforcement.

Thanks for any imput you can give me!
 
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  #2  
Old 04-22-05, 07:34 AM
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you don't need either if you have good clay bottom . if not use either if you pack it, it will be tight with no room for the cement to get arond and bond to the rocks. If you leave it unpacked your cement will get a better bond to the rocks. Always form it up first, get the ground level and how ever many inchs of rock you want leave the form that high off the ground. form it, lay the rocks and pour it.

I never put a sub layer, the only time you relly need it is if it is going to be suppoting weight, like a pool foundation or a house.

I have torn up slabs that had been down for years and found brick layers as a sub.
 
  #3  
Old 04-22-05, 04:07 PM
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If the soil is disturbed and packed or unstable such as some clays, a base will provide a solid underpinning for the slab. If you use crushed rock and dust, it will need to be packed. It will pack substantially. Pea gravel, on the other hand won't pack. Place forms after the base is down.

Hope this helps.
 
  #4  
Old 04-25-05, 04:34 AM
hermmona
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Great! Thanks a lot for the advice!
 
  #5  
Old 04-29-05, 03:10 AM
hermmona
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Ok, I just found out that there are different sizes of pea gravel, and not all suppliers carry the same ones. What would be the best size to use for my project? Remember that it will only be used as a patio/basketball court, nothing else, no additions or cars will ever be parked on it. I have now heard of pea gravel #8, #57, and decriptions such as blackeyed pea size, nickel-dime-quarter size, etc.

Thanks for any help you can give me!
 
  #6  
Old 04-29-05, 06:17 AM
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For this application, buy the cheap stuff.
 
  #7  
Old 04-29-05, 01:10 PM
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Pea Gravel vs. Crushed Stone

It's pretty cut and dried. Pea gravel is used for drainage and Crushed Stone is used for support. Sit on any bean bag and the beans will displace themselves in the area of least resistance. Sit on a bag full of cubes and pyramids and you'll feel a little uncomfortable.

The rigidity of crushed stone makes it an ideal base material to support concrete if you have cracking concerns. But don't be fooled. Your concrete will crack, guaranteed. But a good rigid and compacted base will keep the individual mini-continents from shifting. The concrete doesn't need to adhere to the stone base, there is no advantage to that. If your going to use pea gravel, in my opinion, your wasting time and money. It simply doesn't compact as someone else mentioned. If you think you need stone, do the right thing and rent a compactor, put in the 5 or so inches of 1/2- 5/8ths crushed, and then set your forms. Compact the whole thing at least three times, and make sure you compact the empty hole first.

George
 

Last edited by Doug Aleshire; 05-07-05 at 08:46 PM. Reason: No Advertising or Soliciation Allowed
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