Upvote 1 Views Followers Write an Answer Register now or log in to answer. Some reasons of cracks are: Non structural cracks as result of overtrowelling a rich mix. Structural cracks caused by differential movement of the foundations, moisture expansion or drying shrinkage of masonry units, or thermal movement of the roof. Of course the thickness of plaster may cause cracks. Upvote 2 Downvote 0 Reply 0.
The thickness of plaster may cause cracks, Poor workmanship and curing. Upvote 0 Downvote 0 Reply 0. Answer added by echo gumay, SR. Cracks in the plaster may result due to different reasons: Evaporation if the wall is not protected from sun and wind which can cause map cracking or dry shrinkage cracks.
Suction into the walls if the blocks are absorbent and they have not been dampened which might cause drying shrinkage cracks. Bad or badly applied rush coat Bad plaster workmanship: high thicknesses, no curing Insufficient curing of rush coat or plaster which can cause de-bonding. Bad preparation: leftover of dust, or loose particles on substrate Excessive water in the plaster Immature finishing. They are usually due to over-troweling a rich mix render.
Map crazing: is similar to crazing except that it is usually deeper sometimes going through the plaster and the hexagons of the pattern may measure up to mm across. Drying shrinkage cracks: are ther result of moisture loss after the plaster has hardened. When water is not enough in the mix, then plaster cracks will also occur. Non-structural cracks repair Solution. Non-structural cracks repair: crack without de-bonding In case of non-stuctural cracks, the method of repair depends on the assessment of the defect and the cause of its occurance: Plaster cracks without de-bonding: Hair cracks without de-bonding are usually best left alone.
If necessary they are repaired with weberep FFR Large cracks without de-bonding are repaired with weberep NSG after the opening of the cracks and thoroughly cleaning and washing them.
Plaster Non-structual cracks repair: Masonry block Plaster de-bonding on normal block or light weight blocks: De-bonded plaster is repaired after removal of the entire de-bonded surface and make the necessary substrate preparation for the new plaster as per below steps: 1.
Substrate preparation All bases should be sufficiently rigid, clean of any surface contamination that may prevent good suction.
Dampen the substrate before few hours from the plaster application Fill the empty gaps in the joints of the block wall with block mortar weberbloc fix or weberbloc fix LW Plaster application Depending on the type of substrate, plaster should be recommended: For normal and hollow blocks: use weberpremix hand or weberpremix SP or weberpremix SP-1 For light weight block: use weberpremix SP or weberpremix SP3-FL Spray the plaster on the dampened and prepared surface or apply it manually with a plastering trowel at a thickness between 10 and 20mm in one layer.
For higher thicknesses kindly consult the technical department. Follow the application method statement instructions Finish the surface with a wooden or steel float as required Let the product set properly on the surface before any curing Cure for 3 days. This study is very important to select the crack repairing process. While repairing and prevention of cracks we should have to know what type of crack it is and why it is developing.
To inspect cracks following points we have to keep in our mind. Period of crack- we should have to notice it is stable or developing continuously. We have to inspect this every day. Because continuously developing cracks may be very harmful to structure in the future.
Physical inspection- we should have to inspect the width of the crack, length of the crack, how much crack is deep within. If it is surface crack, we can repair. But if it is throughout from one side to another it may be a very serious issue also which can be a reason for leakage. We should have to find the reason for crack and should have to take immediate action.
Location of cracks- Inspect the location from where a crack is starting. If location is the center of the beam then it signifies that crack is developing due sagging of beam. If the location near corners of door and windows then it signifies that it is occurring due to the settlement of the structure and this can be a serious problem.
A direction of crack- whether the crack is vertical, horizontal or diagonal, we have to notice. This can help us to decide the reason behind the formation of a crack.
If it is vertical it may be due to the settlement of building which is serious. Horizontal cracks may develop due to loss of moisture in the mortar between joints if joints not filled properly that horizontal cracks can develop. Save my name, email, and website in this browser for the next time I comment. This site uses Akismet to reduce spam.
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