For the device of concrete screed is cement, sand and water. If you poured the Foundation or floors of a large thickness, add fine gravel or medium gravel fraction. That is, the stones should be the size of 20/40 mm. Screed is the best, and in many cases the only variant of the device of the preparation of the leveling base for the final coating.

The causes of cracks and deformation of the screed

• violation of manufacturing technology
• the proportional composition of ingredients does not match the required
• poor quality or insufficient quantity of binder (cement)

For the device of the screed sand should be medium-grained, extracted from the quarry. River sand for concrete, the. Take the cement grade not lower than M300, optimally – M400. Before preparation of the solution the sand you need to sift, thus freeing it from mud splashes and dirt. The amount of water is adjusted experimentally until the mixture sufficient viscosity and plasticity. If these conditions are not met, the probability of cracking is greatly increased.

How to repair coupler?

If while pouring a cement-sandy solution it is not well compacted, inside the concrete creates small air cavity. Cracks formed for this reason, begins to mend only after it removed a layer of concrete over these cavities. To determine their presence is quite simple: you need to widen the crack as far as she allows it. Then you need to remove the dust and dirt, and treating the concrete surface primer deep penetration, which is designed for these works.

Further, the prepared cement-sand mixture. It should consist of 1 part cement and 3 parts sand. Before pouring the concrete by spraying with water. This will prevent the absorption of moisture from the screed freshly prepared solution. After pouring the solution of the seal, piercing a metal rod.

If the concrete laid over pigment or sand, the surface may be covered with small cracks with a thickness of 1-2 mm. In this case, you can use Vetonit, Rotband, Horizon or other dry spackling mixture. The deepening of the screed should be carefully vacuum cleaned and primed with composition of deep penetration. Then prepare putty and using a rubber or metal spatula to seal the crack.

Note that as the drying of the repair composition, he tends to get involved in the deepening. Therefore, putty in most cases you will have two times. The last layer – lining. When applied, ensure that it was flush with the floor surface. After drying putty should be sanded with a special mesh with mesh size average size of 0.8-1 mm.