Common quality problems and treatment methods of plastering mortar
(1) Empty drum
The main reasons are as follows: ① the base treatment is not clean, such as dust and loose matters, mold release agent and oil stains on the surface of the base, which will affect the adhesion between the plastering layer and the base. ② If there is a concave part or one-time plastering is too thick, the mortar layer has been separated from the base layer due to gravity before the mortar is dried. ③ Improper interface treatment or no interface treatment, too smooth base surface, can not inhibit the dry shrinkage of mortar, resulting in the separation of the mortar layer from the base. Before plastering, the base course shall be cleaned, and the wall shall be watered 2-3 days in advance. The construction can be started only after the water penetration depth reaches 10 mm. If there is a deep pit, the mortar shall be leveled in advance. In addition, the interface mortar shall be sprayed in advance.
(2) Delamination
Mainly because the bottom ash layer is too dry. In addition to the construction in accordance with the specifications, if the bottom layer is found to be dry, it shall be moistened with clear water, and the surface layer shall be plastered after the bottom layer is moistened thoroughly. 　　　
(3) Blast ash
The main reason is the poor quality of materials, impurities or soil. Before construction, the material quality shall be checked carefully, and the sand shall be screened before use. 　　
(4) Crack
The main reason is that the plastering layer is too thick without crack resistance measures or cracks due to hollowing. If the plastering surface is very thick, the bottom layer shall be filled first in the construction, or the anti crack agent shall be sprayed after the bottom ash is plastered. 　　
In case of the above situations, the cement plastering mortar shall be reworked and repaired. During the repair, the peeling, hollowing, ash blasting and cracks shall be removed, and then the partial plastering shall be carried out according to the specification requirements.
Common problems and treatment of ground mortar
(1) Cracking
Due to the change of temperature difference (thermal expansion and cold shrinkage), the ground is damaged and cracks appear; or because the base is very wet, in the process of mortar solidification, the ground mortar reacts with a part of water, the rest of water is evaporated, and the mortar volume shrinkage after water evaporation causes the ground cracking. Therefore, the base course shall be cleaned in advance and the ground shall be watered 2-3 days in advance to keep the ground moist and free of open water. In addition, the setting time of the ground mortar shall not be too long.
(2) Ground sanding
① The bleeding of mortar causes the fly ash in the mortar to float up, which results in the phenomenon of sanding. ② The unreasonable mix proportion of mortar and the high content of admixture lead to the poor wear resistance and sanding of mortar surface. Therefore, in the design of the ground mortar mix proportion, it must be designed in combination with the construction environment, and can not blindly think that the laboratory data can meet the standard requirements.
(3) Insufficient mortar strength
Too high water cement ratio results in too high consistency, reduces the strength and hardness of the ground mortar surface, and affects the wear resistance of the ground. During mixing, the water consumption of ground mortar shall be strictly controlled, and the consistency shall be controlled between 45-55mm.
Problems and solutions of segregation of dry mixed mortar
(1) In bulk mobile silos, the mortar in the first and last part of the bulk mobile silos is easy to separate
Solution: keep the amount of dry mixed mortar in the bulk mobile silo at the construction site not less than 3 tons, so as to avoid too large height difference of blanking and segregation during the process of entering the bulk mobile silo.
(2) The dry mixed mortar in storage tank and transport vehicle is easy to separate
Solution: the dry mixed mortar in the storage tank and transport vehicle shall be stored in full tank as far as possible, and the transportation shall be uniform and stable.
(3) Too slow loading and unloading speed makes dry mixed mortar easy to separate
Whether it is loading, pumping or tank unloading, the loading and unloading volume shall be large and the speed shall be fast. The experimental results show that the phenomenon of "segregation" of dry mixed mortar with small amount of material, lower speed of cutting than that with large amount of material and faster speed of cutting is serious.
Solution: increase the hole diameter of silo discharge port, and speed up the discharge speed
(4) The capacity of the mixer under the bulk moving silo is small and the amount of mixing material is small, which is also the cause of slow discharging speed and poor mortar quality
Solution: consider retrofitting the mixer capacity below the bulk mobile silo or installing a large capacity mixer.
Quality problems caused by nonstandard construction and Solutions
(1) One time plastering is too thick during construction, resulting in mortar cracking
Solution: according to the standard construction operation, one time plastering should not be too thick. If the external wall plastering thickness specification requires that each layer should be 5-7mm thick, and the total plastering thickness is more than 35mm, strengthening measures should be taken.
(2) When the mortar is applied on the base or base which is not suitable for its strength grade, the shrinkage of the mortar is inconsistent with that of the base, resulting in the cracking of the dry mixed mortar
Solution: mortar of appropriate strength grade shall be used for various wall materials.
(3) No measures are taken at the junction of different materials, resulting in cracking of dry mixed plastering mortar
Solution: the junction of different materials shall be treated with reinforcing mesh.
(4) Cracks and cracks of dry mixed plastering mortar caused by no watering or too much watering of masonry
Solution: according to the standard construction operation, such as for sintered brick, autoclaved fly ash brick, water before plastering.
(5) When the autoclaved brick and other masonry do not reach the specified age, the masonry and plastering construction will be carried out, resulting in the cracking of dry mixed plastering mortar
Solution: all kinds of block materials shall reach the specified age, and can be used only after the volume is stable. For example, the age before use of autoclaved brick shall not be less than 28 days.
(6) The dry mixed plastering mortar and dry mixed ground mortar do not maintain moisture in time after setting, resulting in mortar shrinkage and cracking
Solution: timely moisturize and maintain the mortar after setting.
(7) Other materials, such as mortar king, sand, lime, etc., are mixed into the construction site, resulting in the decrease of mortar strength, even peeling and cracking
Solution: it is forbidden to mix other materials into the mortar at the construction site without the permission of the mortar manufacturer.
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