Posted: 5/24/2010 11:08:22 AM EDT
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I know of at least 2 concrete truck drivers here. I am widening my back driveway about 10X40 feet. It is steep. I have it dug out 4-5 inches. If I throw in a bunch of rebar do I need to put gravel down first? I don't plan on anything over 10,000 lbs. with 4 wheels being on it. Any advise on types of concrete?
I just had a guy tell me I need to put a couple of inches of gravel in first, that would mean digging it out more. I am going to have somebody else do forms and concrete but I want to know what is needed. |
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The rule of thumb, and often building code too, is to never pour over any fill. So it sounds like you're good to go. Specify plenty of control joints. Anything larger than 10'x10' is pretty much guaranteed to crack, no matter what it's poured on, and no matter how much reinforcement is utilized. |
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Well depth has a lot more do with "how much concrete do you wanna buy" rather then "will it settle?". 1" thick by 400 square feet is approx. 1.3 cubic yards. Thats an extra $100+ in concrete. No idea what the current price of concrete is, but I can guarantee its more then a yard of road mix and 20 mins with rake/shovel/hose/plate compactor. 3.5" iches ( the depth or a 2x4) is fine for most driveway type applications provided the ground underneath is compacted well enough.
You can use wire mesh instead of rebar, or you could tie it into your existing slab with rebar dowels, or you could buy fibermesh( ground up fiberglass) in your concrete and skip the rebar completely. As posted, control joints ever 10 feet or less, your shit is gonna crack, you want it to crack inthe control joints and not across the slab face. I havent done residential concrete in years but we didn't go crazy with driveways when I did, unless the owner wanted something extra thick for some reason and wanted to pay for the extra mud. |
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Quoted: I am widening my back driveway about 10X40 feet. Like NWRed said, 1.3 yds per inch. If you think its actually 5 inches, figure 6". 8 yards firm order. Dont run short over a hundred bucks. It is steep. Tell the order taker to put STEEP GRADE-4" SLUMP MAX on the ticket I have it dug out 4-5 inches. 10,000 lb max? Plenty deep? Remember a 2x4 is not 4 inches. If I throw in a bunch of rebar do I need to put gravel down first? I would use fibermesh, mixed in at the plant over rebar or wire mesh. Price is probably same, much easier to use and better results imo. You do not need gravel-but make sure your base is well compacted. I don't plan on anything over 10,000 lbs. with 4 wheels being on it. Thats not a lot of weight. We cross 50 yr old sidewalks daily at 35+ tons and most dont break. Any advise on types of concrete? A standard 4000 with air will do you well. If you let the producer, they will charge you list price. Call around and shop price-there is a recession, make them price it good. When you place the order ask for a couple test cylinders to be sent out with the load. It will keep a shady producer honest, and a good producer give you a better mix. I am going to have somebody else do forms and concrete but I want to know what is needed. Its needed that they not destroy your quality concrete by adding a bunch of water, before, during or after the pour. Its needed that you are there to insure they dont. 10 gallons wont hurt a full load. 50 will. Take lotsa video, before, during and after. If the price is too cheap, the quality will match. You nare going to pay $1500 or the mud, dont let some Goober trash it. Your grandchildren will play on a quality slab years from now... |
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Quoted: What are test cylinders? Samples, of the specific batch used that can be tested later on. More often required for larger commercial or public projects. I have some around here somewhere, from work when we built. Can't recall if the building inspector or contractor requested them. |
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Afterthought....I dont know where you are, weather has a few considerations. Frost/freeze...It needs to set before it freezes. Period. Rain- While some rain isnt bad, a steep hill has a couple things with rain. 1) Getting the truck where you need it if it turns to mud, 2) Steep hills can have river sized runoff. You dont need that on your fresh slab. Curing- In the old days they ALWAYS covered it with burlap and kept it wet for 7 days. Now days you dont see wet curing much. I know their concrete lasted years and years. We dont know if ours will or not. If you plan on backing the truck up inside the forms, the more the truck sinks (not uncommon to see 4" ruts) you can go through an extra yard easily. |
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Quoted: I am going to have somebody else do forms and concrete but I want to know what is needed.
I've poured a bunch of concrete at my place recently: ––driveway with fibermesh ––large patio with rebar and short wall on one side ––10' high x 60' foundation/retaining wall ––machine trowelled garage floor Some opinions: ––pay for a professional for flatwork - it will look much better. foundation walls you can do yourself ––hire a pumper if there are any truck access or concrete placement issues. A boom truck is way better than a line pumper and not much more in price. Ralph's gave me great service and price––even for a DIY-er. ––assume not just 10' control joints but more like 8' (both axis). If you think you can get away with "just a little bigger spacing" you can't. It will crack. Don't let the "pro" talk you out of insisting on more as opposed to fewer control joints. You need to mark where you want them if they're going to be trowelled in. ––the old two-by- in the pour for control joints looks like crap. rent or hire a concrete cutter and cut the control joints in––much better looking. If you cut them in it's easier when the concrete is about two days old. I'm not a fan of trowelled in control joints. If you cut them for goodness' sakes anchor a two-by to serve as a guide so you get them straight. ––the fiber mesh seems to be working fine for me. it isn't a substitute for control joints. ––if you have a short wall capped with a slab- be sure to have set some angled rebar to anchor the slab to the wall. ––for a driveway I think the wire mesh is sufficient instead of rebar. ––I hate exposed aggregate, I think it's a slipping hazard. Go brushed. Sorry, it's my preference. |