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. If this all seems a bit overwhelming, we suggest reaching out to a professional concrete contractor.
You should not pour concrete directly on the ground before preparing a proper concrete base. The minimum best practice is to thoroughly prepare the ground by leveling and compacting the subgrade. Then add a subbase of gravel for additional load support of the final slab if needed.
Concrete slabs require a hard and compact soil for a foundation to hold it in place! If the slab was poured on the native ground then Mother Nature has done the contacting with the rain and gravity over a long period of time.
As a general rule, stay away from using sand as a subbase. You're better off using gravel. Your concrete will last longer and have less of a chance of cracking over time.
Can you pour concrete over wet dirt? Yes, you can the water will make it take longer to set up and extend your finish time. I wouldn't pour concrete on it though unless the compaction of the ground is compact enough. Wet dirt is fine as long as its compacted wet dirt.
What Material is Used for a Slab Base? The base in concrete construction is usually a form of crushed stone. Most concrete contractors want a mix of coarse and fine aggregate to create a compactable base that is going to be safe for settlement and drainage.
You are not required to have a vapor or moisture retarding barrier for outside concrete pads or unheated buildings. Although a vapor or moisture retarder or barrier is not necessary beneath concrete floors used for unheated carports, driveways, and outbuildings, some DIY enthusiasts and builders recommend it.
A 4 inch thick concrete slab must be covered with 3 inches of gravel. The best gravel is gravel with a depth of 3 inches, but it is also ideal for a 4 slab floor. Most driveways require at least 6 inches of stone crushed or gravel.
As a rule of thumb, concrete slabs supporting lighter weights such as paths, patios and shed bases will need to be 75-100mm thick, while driveways and garages need to be at least 100mm thick. Slabs intended for commercial use should be at least 175mm thick and reinforced.
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.
Paint – Paint is another material that has no natural bonding agents, so concrete generally won't stick to it very well. Oil – Oil or oiled surfaces are often used to make the surface resistant to concrete bonding.
Why Do Builders Need an Under Concrete Slab Vapor Barrier Plastic? An under-slab vapor barrier protects the subfloor and, subsequently, the main floor from moisture by adding a protective layer underneath the concrete foundation before it is poured on wet. Underneath every building, in the ground, is water.
Concrete has relatively high compressive strength, but significantly lower tensile strength. As a result, without compensating, concrete would almost always fail from tensile stresses (Stress (mechanics)#Mohr's circle) even when loaded in compression.
It is important to keep in mind that dry-pour concrete may not offer the same level of strength and durability as wet-mix concrete. Dry-pour concrete can also be more prone to cracking and shrinkage, which can lead to structural issues and the need for costly repairs over time.
Although the terms cement and concrete often are used interchangeably, cement is actually an ingredient of concrete. Concrete is a mixture of aggregates and paste. The aggregates are sand and gravel or crushed stone; the paste is water and portland cement.
Instead, use a layer of gravel underneath your concrete slab. Because concrete is porous, it absorbs water. If you place concrete directly onto dirt, water will collect under the concrete and slowly erode the bottom of the pad. Gravel prevents this erosion by allowing water to drain away from the concrete.
Mudjacking. A type of sand-cement slurry (called “mud” in the industry) can be used to fill voids under concrete slabs. This mixture of sand, cement, and water is pumped through holes drilled in a slab foundation to fill voids underneath.
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. If this all seems a bit overwhelming, we suggest reaching out to a professional concrete contractor. Razorback Concrete is always willing to work with you.
Because concrete is a very porous material, it will absorb any moisture that it contacts. This can cause pooling. Without crushed stone, pooling water will settle under it and erode your slab. Adding a layer of crushed stone will add proper drainage, as well as create a barrier between your slab and the ground.
To prevent cracking and crumbling, concrete patios need to be built on solid, well-drained soil. If you live in a region with lots of clay in the soil, you will need to dig down further and backfill with layers of compacted sand and gravel.