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Concrete is one of the most used materials in masonry, mainly in single-family houses for the realization of floors and floors. Hence the interest of the questions that concern him.

5 questions about patching concrete floors

When a concrete floor is not quite level, or when it has high roughness, it may be more interesting to patch it than to pour a thin screed. The point on the subject in 5 questions-answers.

How to patch a concrete screed in a garage?

On a concrete garage screed made at construction, how to make a patching? Is it possible to make a fiber patch (Weber Niv Pro, for example) and leave it naked? Will it resist the passage of a car?

Apply a fiber-reinforced smoothing on a concrete screed is possible, provided that it is dust-free and free of grease. Theapplication of a primer is desirable.
For a garage, it is better then to apply a concrete floor paint, even a resin, which will provide superior resistance over time and facilitate cleaning, by preventing oil or grease stains from becoming encrusted. Specific floor paints should be retained for circulation use. Ordinary floor paints, used for staircases or technical rooms, react with tire rubber and sometimes break down on contact.

How to upgrade a concrete slab?

An exterior concrete slab does not have the same level everywhere. Will a special exterior patching be enough to remedy the problem?

To level a concrete slab, the solution of the patching is actually the most suitable. Everything depends on the thickness to catch up. If this thickness does not exceed 30 mm, there are fiber cemented plasters for outdoors that allow such occasions. If the differences in level require greater thicknesses, then the realization of a real mortar screed.
In all cases, the slab has been previously thoroughly cleaned and degreased.

How to level an uneven concrete floor?

In a garage, concrete was added on a large enough part of the ground to close a hole used for the evacuation of water. The covered portion is completely dented and raised above the base floor. How to smooth the whole and then put a flooring more welcoming than raw concrete, knowing that the ceiling height is very low? Which simple coating to choose? How to ask?

Theflattening of a concrete floor depends on the size of existing hollows and bumps.
If these hollows and bumps are limited to a few millimeters (up to 3 cm), a floor patching enough. This type of product is ready to waste in DIY superstores. It is very liquid and very easily takes its shape (it is self-leveling), after having been spread with a wide spatula or a trowel.
If the defects are larger, two solutions are possible:

  • pour a mortar screed, consisting of sand and cement, which implies a more complex implementation;
  • establish a dry screed, with a layer of granules constituting the form of regularization and panels (specific plasterboard, for example), on which the coating will be placed.
For the choice of flooring - floor paint, tiles, PVC... -, everything depends on the final use of this garage. In all cases, it is necessary to wait until the patching or the mortar screed (if it is the chosen solution) are perfectly dry before laying the floor covering. The drying time depends on the season, the ventilation of the room, the thickness of the leveling compound or the screed. A period of one week for patching and three weeks for a screed appear a minimum to respect.

Should a primer be applied before patching?

A garden shed was mounted on a raw concrete slab. The concrete (one year) was brushed dry and dusted. Is it necessary to apply a primer before applying a patching compound?

The laying a garden shed can be done directly on a smooth slab. If the concrete is healthy, dry and shows no traces of foam or signs of pollution, but coarse and uneven on the surface, it is possible to dispense with applying the primer to make a smoothing.
Nevertheless, given the limited surface area and the reduced cost of a primer, as much as applying one layer: it is an additional security.

Does a fiber patching resist the passage of cars?

A sill has been made, it is planned to add a special exterior fiber patching. Will it resist the passing of cars?

A well-made concrete sill (thickness, dosage, reinforcement, casting) can withstand the rolling of cars without the need for patching. If one nevertheless wishes to add a patch, it may be interesting to apply a primer to the concrete already made. And choose a product, fribré or not, of classification P4S (UPEC).

How to calculate a quantity of concrete needed?

How many bags are needed to make a slab of 2 x 3 m and 10 cm thick? This screed will be made with concrete or mortar sold in bags ready for use.

First, it should be noted that we speak of concrete (cement + sand + gravel) for a slab and mortar (cement + sand, without gravel) for a screed. This constitutes the thin layer superior to a soil, established on the slab itself. Here, the slab must be made with concrete (not mortar) ready for use. We usually count 20 kg per m2 and per cm of thickness. In your case, 6 m2 on 10 cm of thickness, you must multiply 20 kg by 6 and by 10, that is to say 1200 kg. With 30 kg bags, you will need 40 bags of concrete.

How to change the slope of a concrete slab?

Modify the slope of a slab

How to redo a concrete slope for a car parking space? Which product to use? The slab is 15 m2 (5 x 3 m) but the slope was not done correctly because it goes down to the house and not to the street as planned. Since this place is between 3 walls, water does not flow and stagnates. There are also holes and irregularities. There is a total of 15 m2 between 1 and 3 cm difference.

If this concrete slab has been carried out by a company, it is up to it to assume the consequences of its errors and to correct these differences of level. If for various reasons an appeal is not possible, you can implement a catch-up, provided that the slab is clean, that is to say free of dust and grease. The screed will ideally consist of a fiber mortar in order to avoid any subsequent cracking. The application of a primary hooking is recommended before pouring the screed.

How to repair a crack on a concrete wall?

This is an apartment built in the 1970s. By removing the wallpaper on a wall it was discovered a crack resting with plaster, crack that reworked. Scraping the plaster there is the presence of a crack in the wall. It is a concrete apartment separation wall. This is not an exterior wall. The crack runs from top to bottom. What are the products to take this crack in the wall before remaking plaster?

This is probably a moving crack, which will continue to evolve more or less in time, depending on the seasons, the cold, the heat, the movements of the soil, etc. In this context, the most rational solution is to open this crack sufficiently. Then remove all non-adherent parts and fill the crack with soft masonry putty. This patching area will remain flexible, perhaps a little visible, but will have the advantage of not cracking anymore.

How to upgrade a concrete slab?

An exterior concrete slab does not have the same level everywhere. Will a special exterior patching be enough to remedy the problem?

To level a concrete slab, the solution of the patching is actually the most suitable. Everything depends on the thickness to catch up. If this thickness does not exceed 30 mm, there are fiber cemented plasters for outdoors that allow such occasions. If the differences in level require greater thicknesses, then the realization of a real mortar screed.
In all cases, the slab has been previously thoroughly cleaned and degreased.

What is the difference between a slab and a screed?

A small landing of 1.50 m wide and 2.60 m long must be realized. Breeze blocks will form the ground. Are the 5 cm of slab made of cement and sand or concrete gravel?

With a thickness of 5 cm, it is in the presence of a screed, which will consist of a mixture of cement, sand and water. We consider that we are in the presence of a concrete slab, this time made of concrete (cement, sand, gravel, water) most often armed, from a thickness of 10 cm.

On the same topic

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    • How to make up a difference in level in a room?
    • Can I use printed concrete on the inside?
    • How to measure the severity of cracks in an apartment wall?
    • Install self-adhesive PVC strips on a screed
    • How to catch the false-level of a concrete slab?
    • Choosing between a chemical seal and conventional expectations
    • How to put cladding boards on a painted wall?
    • How to raise a concrete slab?
    • What material for the structural work in self-construction?
    • How to improve the flatness and finish of a concrete floor?
    • Can one sink one slab on another?
    • Can we fill holes on the ground by patching?
    • Can we catch up on concrete that has dried too quickly?
    • Overlay two concrete slabs
    • How to make a polished concrete?
    • Tinted concrete floor
    • How to plaster a garden shed
    • How to pour a concrete slab?
  • DIY tips
    • The properties of concrete
    • Scrap concrete
    • Admixtures for concretes and mortars
    • 3 techniques for making a concrete slab
    • Use a concrete mixer to spoil concrete
    • Insulating concrete slab and screed
    • Pouring a cement screed on an old floor
    • All about concrete reinforcement techniques
    • Mixing mortar: preparing the sand
    • Make a mortar screed on a slab before tiling
    • Floor cleaning and patching

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