Pouring a Concrete Slab: Mistakes to Avoid
Pouring concrete slab seems like it should be relatively simple to but there are many things that can go wrong. Most of these mistakes can easily be avoided. The information below will explain some of the more common mistakes that can be made when pouring concrete slab.
One of the biggest mistakes you can make when pouring concrete slab is by having the concrete mixture wrong. If there is too much water or too much concrete the slab will not properly cure. Always follow the mixing guide on the back of the bag. Keep in mind when mixing concrete that certain elevations and humidity will hinder the curing process. So, when pouring concrete slab, always be mindful of the mixture.
Concrete is fairly strong all on its own but it does lack tensile strength. In order to keep the concrete slab in one piece for years to come you have to add more reinforcement to the mix. One way is to use glass, plastic or metal fibers mixed with the concrete prior to pouring the slabs. The concrete hardens around these fibers creating a strong bond. You can also use rebar or steel mesh inside the area where you are planning on pouring the concrete slab.
Improper Steel Mesh Placement
One of the problems you may face with using steel mesh as reinforcement in your concrete slabs is difficulty placing them. In order for steel mesh to be effective it has to stay in the middle of the concrete slab. For this to happen you have to pour half of the concrete first and then place the steel mesh. The remaining concrete is then poured on top of the mesh. A good rule of thumb is to pour a little more than half of the concrete so to account for the mesh sinking when new concrete is added.
Not Enough Curing Time
When pouring a concrete slab (and anything else with concrete) you need to make sure that the concrete has enough time to cure. This is important if you plan to walk on it or place furniture on the surface. This is even important if you plan to paint the concrete slab when you are finished. Concrete will harden in 24 to 48 hours but will not be fully cured for up to a week depending on temperature and humidity. Make sure this curing time is in your mind when you are pouring a concrete slab. It is also a good idea to cover the concrete with a tarp until it has fully cured.
Form not Set
When you're pouring concrete slab you need to use a form, which is wood nailed together in the desired shape. It prevents the concrete from spilling out into the yard, garden or other areas. Building the form is easy but just placing it inside the excavated area is not always enough. To use a form correctly a shallow trench should be dug out, the form inserted and then dirt filled in to secure the form. This prevents any leaks.