How Thin Can You Pour Concrete Over Existing Concrete? The thinnest that is usually used when pouring concrete, in general, is about 2 to 2 ½ inches. That also applies to this pouring new concrete over old concrete. Any thinner than 2 inches would be too thin.
Your new layer needs to be at least 2 inches thick. If it's any thinner than that, it'll easily crack under pressure and won't adequately bond to your surface.
Pouring Too Thin
This is the most common application for DIY concrete pouring. Be sure you never make your slab thinner than four inches for any application. Six inches is the minimum thickness for a concrete slab that may see any kind of heavy vehicle traffic.
The minimum thickness of concrete that can be poured depends on several factors, such as the type of concrete mix, the strength of the concrete, and the intended use of the concrete surface. Generally, a minimum thickness of 2 to 3 inches (5 to 7.5 cm) is recommended for concrete slabs.
The usual thickness of a concrete slab is around 10 cm; however, any concrete slab should be a minimum of 5 cm (a 4-inch slab) in thickness no matter what the application.
The thinnest that is usually used when pouring concrete, in general, is about 2 to 2 ½ inches. That also applies to this pouring new concrete over old concrete. Any thinner than 2 inches would be too thin.
Concrete should be at least 2 inches thick to maintain its stability and quality. Most concrete slabs fall between 4 and 6 inches thick, but you should be careful not to make the new slab too high or heavy.
To prevent load-stress cracking, make sure a slab is built over a uniformly compacted, well-drained subgrade, and is thick enough to withstand the kind of use it will get. In residential concrete, 4 inches is the minimum thickness for walkways and patios.
For residential properties, a concrete slab needs to be at least four inches thick to comply with building codes. An additional two inches are recommended if your concrete will regularly receive heavy loads like motor homes or garbage trucks.
Thickness of concrete slab depends on loads and size of the slab. In general, 6 inch (150mm) slab thickness is considered for residential and commercial buildings with reinforcement details as per design. Methods used for finding slab thickness varies for different types of slabs.
A 3- to 4-inch slab will work for the floor of a storage or tool shed, workshop, garden shed, or playhouse.
Concrete that is not moist-cured at all dries too rapidly, and reaches less than half its potential design strength. It will also have a greater number of shrinkage cracks.
Long story short, yes you can pour concrete over dirt. However, you need to follow the process outlined in this article for the best results.
Sidewalks should be at least 4" (100mm) in thickness. Simple slabs for small foundations, bases, etc., normally 4" to 6" (100mm to150mm) thick, depending on the load they must bear. Slope the walk away from buildings to provide proper drainage.
In hot weather, concrete may crack if joints are not cut within 6 – 8 hours after finishing. The rule of thumb is to cut joints as soon as the concrete is hard enough that the edges don't ravel (dislodging the aggregates) by the saw blade.
Rebar is not necessary for every concrete project. The general rule of thumb is that if you are pouring concrete that is more than 5 inches in depth, you are probably going to want to add in some rebar to help reinforce the entire structure.
Another "old rule of thumb" for mixing concrete is 1 cement : 2 sand : 3 gravel by volume. Mix the dry ingredients and slowly add water until the concrete is workable. This mixture may need to be modified depending on the aggregate used to provide a concrete of the right workability.
Working With Ready-Mix Concrete
And, if you mix it yourself, it's the cheapest way to make your slab. For most do-it-yourselfers, the best material for building a concrete slab is a ready-mix, crack-resistant concrete product. The wet mix is poured into a prepared wood form, then left to cure.
The general rule of thumb is that concrete takes about 28 days to dry for every inch of slab thickness. Within 24 to 48 hours, the concrete will be ready for foot traffic.
Moreover, the minimum thickness of any two way slab without interior beams should not be less than the following: For slabs without drop panel 125 mm. For slabs with drop panel 100 mm.
How thick will your patio slab be? Four inches is the minimum thickness for a concrete patio. You'll want to make it six to eight inches thick if the patio will support a structure such as a gazebo or hot tub.