How to prevent mortar cracking, what is the cause of cracking mortar cracking

1.Adding water reducer to concrete and mortar to reduce the amount of water can reduce the volume shrinkage caused by the evaporation of excess water, and the effect is very obvious;

2.The addition of micro-expansion agent in concrete and mortar has a certain expansion effect in the hardening process of concrete and mortar to compensate for their shrinkage and reduce or overcome the generation of cracks;

3.Polypropylene staple fiber is mixed in concrete and mortar, and every 1m2 mortar or fine stone concrete is added, and there are at least ten to ten fibers in fiber mortar and concrete per square decimeter section, which improves its tensile strength and resists the tensile force of concrete and mortar;

4.Polymer glue is added to become a polymer mortar. It is generally used in a relatively flat base with a thickness of about 2 8mm, and the dosage is:

The weight of the solid component of the polymer glue is the amount of cement, that is, the poly-ash ratio is, such as the emulsion with 50% solid content, and its content is 6% 8% of the weight of cement. It overcomes cracking and other surface defects of the mortar screed;

5.Cover the mesh cloth. In cement mortar or polymer cement mortar, impregnated alkali-resistant glass fiber mesh cloth or polypropylene mesh cloth is added, so that the crack resistance can be improved and the micro-cracks of the screed layer can be avoided;

6.Mixed with lime to make a mixed mortar. Lime mortar is mixed into cement mortar, and the general ratio is cement

Lime:Sand 1::4 5

The strength of the mixed mortar is generally greater than 5MPa, which can meet the strength requirements of the base layer and limit the cracking of the screed layer to a great extent;

7.Set up the lattice seam. When the thickness of the concrete or mortar screed layer is greater than 20mm, the lattice joint should be set according to the requirements of the specification, and the joint spacing should not be more than 4m, generally located at the end joint of the plate.

In this way, the cracking deformation of the screed layer is concentrated here, and then the sealant is embedded in the joint, which can reduce or prevent the plane cracks from occurring;

8.Surface calendering: After the surface of the concrete or cement mortar screed layer is flattened, the secondary calendering process is carried out or the calendering machine is used to calender the surface cracks can be effectively controlled;

9.Adequate maintenance. Concrete or cement mortar curing is crucial, one to timely cure, two to maintain in place, to ensure that the surface of concrete and mortar wet, three curing time is not less than 7d

Only in this way can all the previous measures play their due role, otherwise the adoption of multiple measures without maintenance will be in vain;

10. Enhance the structural stiffness and reduce the influence of structural deformation on the leveling layer, which is the embodiment of the perfect design of the structure.

1. Reinforced net.

2. Ensure cement.

3. The water-cement ratio must be correct.

4. There must be no impurities in the sand, and it must be sieve.

5. After completion, it must be closed and maintained, which is the easiest to ignore, but it is quite important in the later stage.

The cracking of anti-cracking mortar is the reason why the density of the insulation board is too low

The density of the insulation board used for external wall insulation of anti-cracking mortar is mainly 18 22kg m3, but in the construction process, the construction unit is often shoddy, and the insulation board below 18kg m3 is used, which is easy to cause cracking of the plastering mortar layer due to low density, easy deformation and poor impact resistance.

When pasting the insulation board, the full adhesive method should be used, that is, the back of the insulation board should be fully coated with adhesive and then scraped with a toothed trowel before being glued to the wall. The polystyrene board should be pasted in a smooth way, and the vertical direction should be staggered line by row, and the vertical joint should not appear in the vertical direction when the adjacent polystyrene board is pasted.

The insulation board joints at the corners of the wall should be staggered and interlocked, and the insulation boards at the four corners of the door and window openings should not be spliced, and the whole polystyrene board should be cut and formed, and the joints of the insulation board should be at least 200mm away from the corners.

Grassroots treatment:

Before construction, the previous process is strictly accepted, and the flatness and verticality of the surface of the plastering base on the outside of the wall must meet the requirements of the specification to ensure the construction quality of the insulation board paste.

The surface of the base layer should be clean, free of oil, dust and other attachments that hinder bonding, protrusions, hollow drums and loose parts should be removed, and the leveling layer must be firmly bonded with the wall, and there should be no delamination, hollowing and cracks. The use of interface agent for interface treatment can effectively enhance the bond strength between the adhesive and the base layer.

There are many reasons for this. Such as: the uneven settlement of the main structure, the shrinkage of the masonry mortar, and the quality of the exterior wall plastering.

The biggest possibility is that the quality of anti-crack mortar and anti-crack putty powder is not up to standard. It's said that it's a flexible amount, and it's too much fraud. If the inner layer of plastering mortar is more flexible than the putty, it may also cause the outermost layer to crack due to deformation.

The most important thing is that the amount of mortar glued to the outer layer is greater than that of the inner layer. Because the exterior wall is from the inside to the outside, the flexibility of the product is also required to be better and better from the inside to the outside, and the outer layer must meet the deformation of the inner layer.

Anti-cracking mortar. At present, the density of insulation boards used for external wall insulation is mainly 18 22kg m3. However, in the construction process, the construction unit is often shoddy, using insulation boards below 18kg m3, due to low density, easy deformation, poor impact resistance, easy to cause cracking of the plastering mortar layer.

2. The aging time of the insulation board is not enough: the self-shrinkage and deformation time of the insulation board in the natural environment is as long as 60 days, but due to the factors such as capital turnover and cost control of the production enterprise, it is usually based on sales, and the natural aging of the insulation board used in a large number of projects has been on the wall in less than 7 days, and the polymer mortar results in the continuous shrinkage of the insulation board after the wall, and the shrinkage stress of this reinforcement mortar is concentrated in the joint of the board, which produces tensile stress on the plastering mortar layer adhered to the insulation board and causes the plastering mortar layer to crack.

Anti-crack mortar is actually a mortar mixed with polymer (glue).

Or a mortar with added fibers.

Although called anti-crack mortars, they can also crack.

It depends on whether the construction, maintenance and other links are done well.

If you do not add water in proportion, if the base surface is not well treated, such as the construction quality of the country is too poor or completely ignored after construction.

Left to dry shrinkage, exposure to the sun, dry hot air, etc., the anti-cracking mortar will still crack.

Of course, there are also so-called anti-cracking mortars that are simply fake and shoddy, cutting corners.

Hello dear! 1. The quality of the plastering mortar material The reasons for the cracking of the plastering mortar caused by the quality of the plastering mortar material itself are: 1. There is too much plastering mortar cement, resulting in excessive self-shrinkage, and the lack of relatively flexible anti-cracking materials may cause the cracking of the plastering mortar.

2. The sand grading in the plastering mortar material is unreasonable, and the large mud content of the sand can cause the plastering mortar to crack. 3. The anti-cracking material of the plastering mortar itself is insufficient, if the construction environment is harsh, coupled with the addition of latex powder, the addition of anti-cracking fibers may cause the cracking of the plastering mortar. 4. The plastering mortar will also cause the plastering mortar to crack if it is not really constructed during construction.

2. There are two main reasons why the external wall insulation wall base may lead to the cracking of the plastering mortar: 1. The reason for the temperature change, the temperature change will cause the building materials to expand or contract, but different materials have different temperature coefficients and deformation stresses. Thermal expansion produces temperature stress at the interface, and once the temperature stress is greater than the tensile strength of the plastering mortar, the material will be displaced, resulting in cracks in the plastering mortar.

2. When the shrinkage stress is greater than the tensile strength of the plastering mortar, the plastering mortar will produce cracks. Therefore, in the construction of external wall insulation plastering mortar, it is necessary to pay attention to the quality of the plastering mortar itself and the wall base of external wall insulation, and prevent cracks in the plastering mortar.

What are the causes of cracking of anti-cracking mortar: Analysis of the causes of cracks: 1

The density of the insulation board is too low: due to the low density, easy deformation and poor impact resistance, it is easy to cause cracking of the plastering mortar layer. 2.

Insulation board aging time is not enough: a large number of engineering use of insulation board natural aging less than 7 days on the wall, the polymer mortar result is that the insulation board continues to shrink after the wall, and the shrinkage stress of this reinforcement mortar is concentrated in the joint of the board, the plastering mortar layer adhered to the insulation board produces tensile stress and causes the plastering mortar layer to crack. 3.

Pulverization of insulation board materials: due to factors such as long construction period or construction in alternate years, the surface of the insulation board is pulverized, and the pulverization interface seriously affects the bonding of the plastering mortar and the insulation board, which can easily lead to the instability of the insulation board or the plastering mortar, causing the insulation layer to fall off or the plastering mortar layer to crack. 4.

The thermal conductivity difference between the plastering mortar and the insulation board is too large: due to the temperature difference and the influence of the outdoor temperature of day and night and the season, the amount of deformation of the plastering mortar layer is very large, and the plastering mortar is easy to produce cracks. 5.

The adhesive material is incompatible and mismatched with the bonded material, resulting in the poor bonding of the insulation board and the cracking of the plastering mortar layer.

When cracks appear on the wall of the cement mortar, in addition to affecting the appearance, it may also affect the waterproofness and stability of the wall. At this time, some measures need to be taken in time to repair the cracks, prevent the cracks from further expanding, and strengthen the toughness and durability of the wall.

Here are some ways to repair cracks in cement mortar walls:

1.Clean the cracks: First of all, you need to clean the cracks, remove the debris, debris and oil stains in the cracks, and use a brush or vacuum cleaner to clean up the dust, sand and other materials around the cracks.

2.Fill the cracks: Use cement mortar to fill the cracks, fill the mortar into the cracks, and use tools such as scrapers to level the mortar on the wall. When filling cracks, you can add some sealant or glue to enhance the filling effect.

3.Plastering and finishing: Once the mortar is filled, a layer of mortar needs to be applied to level the wall. When plastering, it is necessary to pay attention to the combination and proportion of materials, as well as the thickness and quality of the mortar, so that it is similar to the color and texture of the wall, so as to achieve the effect after repair.

4.Add waterproofing materials: If the waterproofing of the wall is poor, you can add waterproofing materials or apply waterproofing paint while filling in the cracks to enhance the waterproofing performance of the wall.

5.Increase toughness materials: In order to improve the toughness and shock resistance of the wall, you can choose to add some elastic materials, such as polymer elastic membrane, fiber mesh, etc., to increase the toughness and durability of the wall.

In short, repairing cracks in cement mortar walls requires the selection and proportion of closed materials, as well as the correctness of construction methods. If the cracks are large or the wall is in poor condition, it is advisable to seek professional help.

Cracking of cement mortar walls: 1. Changes in climate throughout the year. The construction environment of the wall needs to maintain a certain temperature of 5 degrees Celsius as the best, and excessive temperature will affect the degree of coagulation of the entire moisture, which will directly cause the wall to crack.

We generally do not recommend the construction of the wall in the cold winter or hot summer, if you are really in a hurry to move in, we can turn on certain equipment to adjust the appropriate temperature.

2. Effective mixing of wall materials. When the wall is painted and treated, cement, mortar, putty powder is indispensable, after the fusion with water, different kinds of mixing have a most suitable ratio, so that the wall treatment, in order to bring us a longer wall life.

3. There are old injuries in the house. When the house is being built, the construction worker may dig a hole between the walls according to his own convenience, and repair it when it is finished, and the invisible finger marks have caused hard damage to the wall.

4. The foundation of the house is unstable. Many new houses may show a little sign of sinking and cause deep damage to the walls after moving in as soon as possible, which is usually the case of large villas and high-rise buildings.