Q&A for How to Pour Concrete

It really depends on the application, but generally, you'll want to use three parts concrete and one part water. If you're pouring a concrete foundation for a wall or post, you can use more water since the finish won't matter.

Make sure you put mesh or rebar in the form that you built using wood. This will stabilize your concrete and give it better structural integrity.

Yes. Wetting the concrete after it has initially set is a process called wet curing. During the curing process, concrete needs to be protected from moisture loss, and this process helps keep it moist.

If you get quick-dry, then no. But if you get a slow-dry, you can.

You can either vibrate the sides well so that the concrete fills in all the voids on the sides, or you can apply hydraulic cement to the outside when the forms are removed to cover the aggregate.

Call your local foundation contractor. It's not as simple as just pouring a slab onto specific area. In order to pass a routine building inspection, the floor slab for your house is required to sit on a footing and wall foundation. This is not something you should attempt yourself.

Once you rip it out see what your underwater looks like. A stone base is used primarily to help drain water away from underneath the concrete and to keep soil erosion from occurring, which can lead to cracking, etc. If your underwater is solid with hardpack and stone mixture already underneath them you should be fine. If you had your driveway for 45 years then I'm sure something proper is occurring underneath that slab.

It must be above freezing, but the minimum recommended temperature is 40F.

No, remove it and start again. If you had used a slow-drying concrete you could have added to it.

I would not recommend using topsoil under your slab. Topsoil contains organic material and can hold water, causing moisture problems with the slab and potential for the slab to move. A gravel base course will give you the best results.

Yes, but if you ever want to move the fence, it might shake and crack the concrete leading to other bigger cracks.

High strength bleach, unless it's rust stains. If that doesn't bring it up, use boric acid.

Lots has been done using fiberglass as an additive to the concrete. I've had occasion to jackhammer out some fiberglass reinforced concrete and it was much more difficult. One benefit of the glass fibers is that unlike a welded wire mesh or rebar, the fiberglass is everywhere in the concrete.

I would always use a well compacted sub-base. The firmer the sub-base, the less likely it is that the pad will crack.

Your forms should come to the top of the concrete. After putting the concrete inside the form, you will need to use a 2x4 to "screed" the concrete flat and raise the concrete cream to the surface. Your form provides a flat, level surface on both sides of the pad for the 2x4 screed board to slide back and forth. Here's a tip - if your form boards are not quite 100% straight, that's alright. Nail them in so that the high side is upwards in the middle. In doing so, you are ensured that water will run down and away from the middle of the slab.

4 inches minimum with rebar and/or wire mesh. Rebar reinforces your concrete for heavy traffic. (i.e cars) and keeps you from getting large cracks. Mesh does little to help with the heavy traffic but will prevent small cracks from appearing. I prefer to place the rebar and then the mesh on the garage door side of the garage.

Remove or pump out the water first, otherwise it will dilute the concrete.

We poured on plastic for years as a vapor barrier. Now they recommend 2 inches of sand or gravel over the plastic so the water will migrate in both directions instead of going to the surface.

It depends on the depth of your grade and whether you run into any roots or not. More than likely the roots will destroy your slab before the slab hurts the tree.

You'll want to 'tie it together' using a hammer drill with a diamond concrete drill bit, drill 4-6 inches into the side of you're existing slab. Epoxy some rebar into the holes, tying the slabs together. I would also carve an expansion joint there because it will still crack.

Before you consider fixing your floor you will want to figure out what is causing such a major issue. If there are issues such as erosion from improper drainage under the floor then pouring a new floor on top will not fix the issue.

The best conditions are a dry, slightly overcast day (avoiding direct sunlight), you don't want it drying too quickly.