This weekend, I poured a concrete slab behind my shop to put my trash cans on, out of the mud and out of sight. Since the thought of pouring a concrete slab seems a bit daunting, I wanted to write a quick post on the basic steps. The task can be physically exhausting, but a basic slab can be done by anyone! I poured this 3 foot by 10 foot slab in one day!
Click below to download my free concrete checklist and shopping guide!
Rubber boots are also a good idea! And old clothes!
Start with a flat, packed surface. I used a tamper to pack down my soil.
Next, lay a thick base layer of gravel. Mine is 2-3 inches thick. For a small pad, you can buy gravel in bags at your home improvement retail store or most stores with a garden center. For larger quantities you can go to a landscape company and have the gravel loaded in a truck or trailer. Or, many of them will also deliver for convenience.
Next, build a frame for the concrete with 2x4s (at a minimum).
Level the frame, but keep water in mind. I have mine angled slightly so the water will run away from the shop when it rains.
Bracing the frame with wood stakes will help it hold it’s shape when you add the concrete later.
Use rebar inside the frame to add strength to the concrete and help prevent it from cracking in the future. Rebar is available in many different lengths at Lowes and Home Deport or similar stores. I was able to find lengths that would work and didn’t have to worry about cutting it.
Next, Wire together the rebar where it crosses each other so it doesn’t move when you pour concrete into it.
Mixing the concrete
I was able to borrow a concrete mixer from a friend for this project but, these can be rented from Home Depot or your local rental center for a decent price! My local Home Depot has one to rent for $45/day. If you have a lot of upcoming cement projects, I saw a mixer at Harbor Freight for $209!
Concrete can also be mixed by hand for a small sized pad. Last time I did this, I used a big beach bucket like this one, but they actually make pans specifically for it like this one. I won’t lie, it is a lot of work to do it this way, but it’s possible!
Concrete comes in several different types (smooth, quick drying, rough with gravel, etc) so, choose one that will provide a smooth/rough surface as you would like. I didn’t choose the quick drying because I was afraid it would dry before I had time to get the whole pad poured and the imperfections fixed!
Concrete comes in 40, 60, and 80 pound bags. The 80 pound bags are a little bit cheaper per pound, but I did the math and for 20 bags it only saved me a couple of bucks. For the sake of my back, I shelled out the extra $6 dollars for 60 pound bags. Also, for my back I accepted help loading it so I only had to lift each bag once!
I poured two bags at a time into the mixer.
The back of the concrete bag has specific instructions on how much water to add.
This technique lasted for one round of concrete mixing and then I thought “who has time for this?” And this is how I mixed the rest…
Pouring the concrete
I was looking for a wet, mushy consistency without making it too watery. When it felt right to me, I shoveled it into my frame. You could potentially just tip the mixer up and pour the concrete into the frame, but mine didn’t have wheels and I didn’t have a lot of room around my frame to work with.
As soon as you have filled your frame, you screed (fun word, huh?!) by using a 2×4 to scrape the excess concrete from the frame. You’ll want to do this by resting the 2×4 on either side of the frame and sliding it back and forth as you pull it across the frame.
After the frame is full and you have slid your 2×4 back and forth across the entire frame, screeding (had to sneak the fun word in again), you will use a hand float to smooth the surface of the concrete. Lightly tapping the concrete will bring the water up and make it easier to smooth.
If you would like rounded edges on your concrete, you will go around the edges with this concrete edger to make smooth round corners.
If you are pouring a large slab, you will want to put joints in it (like the cracks in sidewalks). These grooves are designed to guide the cracks that will happen as the concrete expands/contracts during the drying process or during temperature changes. You can use this concrete groover to place cracks across the slab. The cracks should be 1/4 the depth of your slab. The spacing should be 2-3x the slab thickness in feet. So, a 4 inch slab should have joints every 8-12 feet. This can also be done with a saw after the concrete dries, but seems more complicated to me.
To give the concrete a texture which can add traction drag a broom across the surface before it dries.
Strong concrete needs to dry slowly, so keeping it moist for the rest of the day will help. You can do this by misting it with the hose or by putting a tarp over the wet concrete and allowing it to dry slowly.
Allow the concrete to cure for 24 to 48 hours before removing your 2×4 forms.
These are the tools that I used for this project:
I hope that you will be able to put this to good use if you’ve been contemplating concrete on your property, and I would love to hear your feedback or success stories!!