This is turning into the year of the backyard improvements, and one of the things we'd like to do is a small addition to the concrete patio in the back. It's nothing much - just 5'x10', but I'd like to get it in sooner rather than later as we're also going to be having a patio cover constructed . Any tips? At 4" deep, I should need around 25 80lb bags. Would it be more practical to have a truck come out? It won't be able to drive to the area so even with a truck we'll need to huff the actual material to the backyard. But it still seems like it would save a bunch of time over dealing with 25 sacks of concrete. Of course it would probably cost more too.

I've got to take off in the morning for a business trip so I won't be real active in this thread for a bit, but I'll make sure to check back on Thursday when I get back home. Any tips on working with the concrete myself and opinions on the bags versus truck question are welcome.

This is probably just the first of a series of backyard advice threads I'll be starting the next few months...

What I'd do is get a bunch of wheelbarrows together, then hire about 5 illegals from a local street corner to haul the concrete from a delivery truck to my form in the yard. I plan on doing something very similar soon, although a bit smaller - mine will be more like 6ft x 6ft as a base for the BBQ I plan on building.

My advice as a mason.......You are probably gonna be better of getting a truck and doing it that way (with wheelbarrows).

If you do it with bags it wont work all that well. You can fit 2-3 bags in a wheelbarrow and by the time you get it all poured the fist ones will have started to harden. A pump truck will cost waaayyyy so you wont want to go that route.

Dig down a bit, lay crushed stone, form it and then pour it. Bug it to get all the air out then smooth. Edge it. Make sure you put expansion joints in to avoid cracking. Once it starts to dry, run a stiff bristled broom over it to texture, then edge again.

Good luck.

Jason

I might have a similar project coming up soon too. Considering pouring a 4x50ft walkway thru my yard.

Would anyone recommend renting one of these?

Rent a mixer like the one in the picture & bring it to the place you want to place the concrete. Figure out how many cu ft each bag will produce. Do not exceed the capacity of the mixer.

Read the bags direction for the amount of water to add. Measure out the quantity of water, don't redneck estimate the water or you will be sorry in the next few years. To much water will lead to scaling of the surface.

If the bag doesn't say how long to mix, follow this. Mix for 3 minutes, let is rest for 2 minutes, then mix for a final 2 minutes. Place the concrete.

Regular bag mix concrete will give you 45-60 minutes to play with before it starts to set. On a hotter day, it will set faster.

Once all the concrete is placed, screed it with a 2x4. After screeding, use aluminium trowels to smooth it out. Do not over work the concrete, you will be asking for scaling, Do not add water to the surface to help you finish, you will get scaling.

After you have got the slab relatively smooth, take a broom & lightly scratch the surface for a skid resistent surface. After brooming. edge the concrete & form your joint.

A 5x10 slab is big enough to require a joint. Joint it into two 5x5 slabs.

The concrete will start to bleed water to the surface, this is normal, do not work the water back into the concrete, let it sit.

Once the concrete has hardened, not dried, enough that it hard to put an indention with your finger (~1-2 hrs) cover it with wet burlap & plastic. This will help the concrete from developing small surface cracking. Try to kepp the burlap & plastic on for 5 days, keeping the burlap wet.

This is how your grandpa placed concrete so many years ago. His concrete is still holding up today, while many of the newer concretes placed are falling apart because of shortcuts taken.

Forgot to add, if you dig up the soil & place rock, compact the soil & rock. Settling is a major cause of concrete slabs breaking.

Your calculations were pretty close. If you buy the concrete in 80 lb bags, you will need 28 bags of concrete.

You get 0.6 cubic feet out of one bag. At four inches thick, your slab is 0.62 cubic yards.

The posters above gave a lot of good advice. You can do the prep yourself. Dig out the area, install the forms and make sure the soil is compact and even prior to pouring the concrete.

I would recommend digging lower then 4 inches and installing a couple of inches of stone gravel. Also use some wire mesh within the slab.

Have you ever worked with concrete before?

If you decide to mix your own concrete, the concrete mixers you rent from places like Home Depot usually can only mix two 80 lb bags at a time. You won't want to do a slab like yours mixing in a wheel barrel all day. You might consider renting two mixers and with some buddies having both going to fill in the pour.

The concrete truck is the best option, but you would also have to rent something else with a hopper that can carry the concrete mix into the backyard.

Wheel barrel loads from the truck to the backyard are possible. You'll need a number of people with wheel barrels and the driver will bitch and moan, but "fuhgettaboutit". There is also the possibility of making a bit of a mess.

Whatever you do, you want all that concrete in the forms as fast as possible while all still wet.

I know someone who extended their patio by using concrete patio pavers. It looks really good. Is that possibly an option for you?

I did mine using 1 foot square paver stones. For added stability, weed resistance, and to suit my anal retentive ways, I leveled the ground well, used 1 ton of pea gravel underneath, along with some stiff mesh wire, and laid mortar mix underneath the pavers to keep them in place and from sinking in spots, etc. The area I did was 12x16 feet.

It's held up great over the past 5 years.

The sidewalks in my back yard are also done with pavers with sand underneath.

As a concrete contractor we would use a tow behind redi-mix trailer for such a small job, such as Cart-A-Way. Mixing by hand is not a good way to go for quality, and back breaking. just trying to finish the concrete so it lasts a couple of years as a rooky will be a challenge.
A truck will cost more with short load and possible time. The tow behinds hold up to 1.5yds and are flexible on time. You will need a place to wash out though. Also, get a full blown mixer type, not the crappy old Ez-Carts.

Quick question(s). Where do you live, what's the water table elevation, and what's the frost line? That's important information, as it dictates how thick a gravel base you need to make. The stone's purpose is to prevent and eliminate frost heave, and if it's too thin, you may as well not even have it. W/o knowing where you live, I can't say how thick you need it to be; an easy way is to contact your local city highway department, and find out what their typical detail for a sidewalk is. That's what you need to go by for your patio section to make it last the longest. A lot of cities have their typical details available online. But make sure it's your city, or one nearby, as what's needed will vary due to the 3 questions I asked you first.

As to mixing it yourself vs. a truck... The small quantity you need isn't going to make it worth getting a truck, unfortunately. Don't try to mix it by hand in a wheelbaroow, though; your back will hate you, and you won't be able to do it fast enough, anyhow. Rent a concrete mixer. Once concrete sets up, you CAN'T just add more next to it and call it good. Concrete doesn't work like that.

Since your slab is 5'x10', hand-form (or saw cut down 1", if you're really ambitious) a joint line to make it two 5'x5' panels. It will crack along this line. The goal is not to try to keep it from cracking (that's a physical impossibility); the goal is to prevent it from cracking where you don't want it to crack. Don't put in an expansion joint, here. You don't want to build two completely independent slabs; you want to build 1 slab w/ a transverse joint in it.

While it's not necessary for strength, a wire mesh will help keep the slab together if it does crack. Make sure to keep the wire about 1" below the top of the slab for this to have its effect. Don't let it go any higher than the 1", or lower than the half-way mark. The lower you put this wire, the less ability it will have to contain the cracks. Wire is one of the things people have absolutely no concept as for its proper use; it's placement depends on what it's purpose is. Wire in the bottom of a slab is for strength; wire in the top of a slab is for crack control. Again, this isn't really necessary for the size that you're pouring, but if you do use it, don't put it in the bottom of the slab; it won't do you any good there unless you're building a driveway or something that'll have a hella' lot of point loadings.

Put in an expansion joint around the existing slab where you're butting up against. DON'T pour your new slab directly against the existing; do that, and something going to spall (really nasty surface chipping) and crack, either the existing or your new. I don't know how large your existing slab is, but I'd want around 1/4" to a 1/2" expansion joint based, if it were me. You should be able to pick up expansion joint material at your local Lowe's/Home Depot/etc, but if you can't, then just use a 1/2" thick piece of non-pressure treated wood (you don't want any chemicals f*ing with your concrete curing, aka, chemical reaction). The wood will shrink when it dries out, and provide enough space for the expansion; not to mention, it's soft, and the concrete will squeeze it if it needs to. Do yourself a favor, though; get a good outdoor caulk, and caulk over top of the expansion material (be sure to only use expansion material or wood that is only 3" tall, recessed 1" from the top of the slab) to prevent water from draining down to your subgrade. This will also give it a nice finished look, and will protect the expansion material and make last a lot longer.

Rent a concrete vibrator for when you're placing the concrete. Air bubbles are not your friend, and trying to do it by hand w/ a stick ain't gonna' cut it.

If the slab is free on three edges an expansion joint is not needed between the old & new concrete. This slab is to small to need one anyway.

To keep the old concrete from getting concrete slobbered over it, you can use a thin sheet of plastice at the joint. Trim it away after the new concrete has hardened.

Wire mesh nay not do much with the size of the slab. You can go with a pre-bagged mix that has fibers. This will help minimize cracking. If done right you will have a maximum of one crack, at the formed joint. This could happen in as little as a few days or in 20+ years.

The Colorado DOT uses a 4" sidewalk, no wire mesh in the standards. Sidewalks are low priority.

Do not use a vibrator on this concrete. Use a shovel to pack it in. A vibrator will make a huge mess & if overdone will knock out the usefull air bubbles.

If you need to shovel snoe in your area, do not salt the new concrete for 1 year.

Thanks for all the tips guys. I'm at the office so I've just skimmed, but it sounds like the best way to go is bags and a rented mixer. I'll read this thread in more detail when I get home tonight.

Props again to XOC members for lots of great yet practical advice.