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Pour a concrete slab and a mortar screed

Pouring a slab requires a large amount of concrete to make it all at once, which results in a perfectly flat and horizontal surface. Make a screed mortar that will cover this sole will be used to support the floor covering (here tiles). A plastic sheet (Polyane) associated with the hedgehog (bottom layer of pebble) prevents rising damp.

Necessary material

  • Cement mixer
  • Shovel
  • watering
  • Cement trough
  • Bubble level
  • Trowel
  • Float
  • Folding Meter
  • Mallet
  • Mass
  • Rake
  • Lady
  • Wood wedges
  • Mallet
  • Lattes and rules of wood

Steps

  1. Concrete manufacturing
  2. Pouring concrete
  3. Pouring mortar screed
  4. Smoothing and drying

Concrete manufacturing

Pouring a slab that requires a large amount of concrete to pour at one time (possibly gradually) you will have to, at least use a concrete mixer or, ideally, order the required quantity of concrete ready, available by a truck. Concrete mixers for DIYers have a deep-drawn steel tank with pallets that ensure a homogeneous mixture of concrete components: cement, sand, gravel, water and any additives. A concrete mixer of this type makes it possible to prepare 100 to 150 l of concrete in one go. The rotation of the tank is obtained by an electric or thermal motor, by a ring gear. The tilting of the tank to dump the contents is obtained by a metal wheel. The concrete mixer, perhaps mounted on wheels with rubber or pneumatic tires, to facilitate the movement. Since the concrete layer must be about ten centimeters thick, you must calculate the cubic volume of the concrete: plan for 300 kg of cement (CEM II 42.5 N, ex CPJ 45) per cubic meter of concrete. The standard dosage follows the 1 + 2 + 3 rule:
- 1 volume of cement
- 2 volumes of sand
- 3 volumes of gravel

Introduction of cement in the tank

Introduction of cement in the tank

1. First introduce the cement into the concrete mixer. If, as here, you use a shovel to load the components, note that its volume is about 5 liters (if you work in the bucket, it has a capacity of 10 to 12 liters).

Introduction of the gravel in the tank

Introduction of the gravel in the tank

2. Then load the gravel. They should normally be of different sizes to ensure a gradual grain size. Use clean river gravel.

Introduction of sand in the tank

Introduction of sand in the tank

3. Introduce the sand into the tank. It must be exclusively clean and dry river sand. If it is wet, it occupies more volume (it is said that it "abounds"). In order not to distort the proportions, it is necessary to correct this according to the rate of humidity.

Addition of water and rotation of the concrete mixer

Addition of water and rotation of the concrete mixer

4. Add water with the watering can. This will allow you to dose the volume. Allow 15 to 20 liters of water per 35 kg bag of cement. Rotate the concrete mixer. The mixing time is about 2 minutes, about twenty turns. To prevent concrete from sticking to the tank wall when you pour it, hit it regularly with a rubber mallet to avoid denting it.

Tilting of the tank

Tilting of the tank

5. Turn the bowl control knob to toggle it. Recover the concrete in a trough. It will allow you, first, to make pads to level thickness adjustment slats.

Ready mix concrete mixing

Ready mix concrete mixing

6. For small areas, you can use ready-mix concrete: cement, gravel and sand are pre-dosed. You can spoil the concrete in a tank, adding water. You will find ready-mixed concrete dosed at 350 kg cement / m3 in 35 kg bags.

Pouring concrete

Adjusting the horizontality of the holds

Adjusting the horizontality of the holds

7. Make concrete pads on the floor. Put on a block of wood. Check their horizontality at the bubble level. To adjust the horizontality of the hold, hit it with the handle of a mallet. The distance between the top of the hold and the bottom of the excavation should be about 10 cm.

Checking the level alignment of the holds

Checking the level alignment of the holds

8. With a long ruler, check the level alignment of the shims with a bubble level.

Pack the concrete to the lady

Pack the concrete to the lady

9. Lay slats between the shims. Pour the concrete. Spread it with a gardener's rake. Fill in the space under the battens. Tamp the concrete with a lady. Start in the opposite corner to the front door. Spread the concrete evenly.

Adjusting the thickness of the slab to the ruler.

Adjusting the thickness of the slab to the ruler.

10. To adjust the thickness of the slab, slide the ruler over the slats. After setting the concrete (but before drying), remove the slats and wedges. Fill the voids thus cleared with concrete. Let it dry for at least 24 hours.

Pouring mortar screed

Control of the horizontality of the screed

Control of the horizontality of the screed

11. The pouring method of the mortar screed is comparable to that of the concrete slab. Slats 2 cm high allow to adjust its thickness. The screed must reach the level, previously identified by a peg fixed to the wall. Check its regularity level with a large metal ruler.

Filling of voids with a trowel

Filling of voids with a trowel

12. Once the mortar begins to set, slide the wood lath. Fill the voids with mortar, with a trowel.

Smoothing and drying

Smoothing with a trowel

Smoothing with a trowel

13. The screed will be smoothed with a trowel and possibly with a trowel.

Remove the peg before drying

Remove the peg before drying

14. The complete drying of a concrete slab takes a maximum of 28 days (variable weather depending on weather conditions): ventilate the room avoiding drafts, at least the first 8 days. Cover the slab with a plastic tarpaulin for the first few days. Sprinkle the screed with water if it is very hot (you will avoid premature drying, source of cracks). Remove the peg before drying.

On the same topic

  • Questions answers
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    • How to make up a difference in level in a room?
    • How to strengthen a wooden floor in attic to develop?
    • How to make up for a difference in level with underfloor heating?
    • How to redo and isolate a ground floor?
    • How to catch the false-level of a concrete slab?
    • How to pave a garage run?
    • How to use a quick setting cement?
    • How to raise a concrete slab?
    • Gravel under a house to avoid humidity
    • How to obtain homogeneous tile joints?
    • Should we make a screed before laying a tile on a concrete slab?
    • How to turn an area of ​​loose earth into a petanque?
    • What quality of sand for a screed and electric underfloor heating?
    • How to raise a slab around a pool?
    • Can we catch up on concrete that has dried too quickly?
    • Is it necessary to use a traditional screed or a dry screed to polish a tile?
    • WHAT IS THE DIFFERENCE BETWEEN A SLAB AND A CHAPE?
    • Drying time of a concrete screed
  • DIY tips
    • Scrap concrete
    • 3 techniques for making a concrete slab
    • Panel floor on dry screed
    • Insulating concrete slab and screed
    • Pouring a cement screed on an old floor
    • How to make earthworks and foundations?
    • Installation of buried PVC pipes
    • Make a mortar screed on a slab before tiling
  • Forum
    • Liability / disaster / tiling
    • Screed, slab or demolition?

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