1. Floor cracks require different treatment methods according to different crack causes.
2. Classification of cracks: Cracks can be divided into stressed cracks and non-stressed cracks.
1. Stress cracks are caused by uneven settlement of the foundation, concrete strength, plate thickness and other factors;
2. Non-stress cracks are caused by temperature, shrinkage of concrete, Caused by factors such as construction, it appears sooner or later. Early dry shrinkage cracks will appear about 2 to 4 hours after pouring is completed, and some temperature cracks will only appear three months to half a year after completion acceptance. Among them, the main construction factors are that the protective layer of the negative reinforcement of the slab is too large (the steel bars are seriously trampled and collapsed), the concrete protective layer at the bottom of the slab is insufficient, or the chloride salt content of the sand exceeds the standard.
3. Treatment methods:
(1) Destructive cracks caused by unqualified cement stability in concrete or chemical reactions caused by mixing different types of cement must be thoroughly treated. The concrete will be knocked out and re-poured.
(2) For cracks caused by stress, targeted reinforcement measures can be taken according to the cause of the cracks.
If there are cracks in the floor that have affected the structural safety, in addition to cutting V-shaped grooves along the cracks and cleaning them, pouring epoxy resin liquid into the cracks under pressure to seal them, flat steel must also be used to seal them. Or carbon fiber cloth and other measures to reinforce the floor. When reinforcing with carbon fiber cloth, for a single crack, in addition to pasting along the seam, it must be pasted at a spacing perpendicular to the seam direction; for multiple intersecting seams, it must be pasted in a tic-shaped pattern, with the spacing being the same as the cloth width. (The fabric width is about 300mm)
(3) The treatment of non-stressed cracks caused by factors such as temperature, shrinkage of concrete, construction and other factors is as follows:
1. For general concrete For cracks on the floor surface, the cracks can be cleaned first, and after drying, the cracks can be filled with epoxy resin liquid or sealed with surface painting. If cracks are found before final setting during construction, they can be treated by applying pressure.
2. For the treatment of other general cracks (with a width between 0.05mm and 0.2mm), the construction sequence is: clean the board joints, then use 1:2 or 1:1 cement mortar to smear the joints, and press Just maintain it flat and close it to restore the look and feel. (Limited to a small number of seams that are not full-length or through seams)
3. When the cracks (width greater than 0.2mm) are large, an eight-shaped groove should be cut along the cracks, and then rinsed clean , smooth it with 1:2 cement mortar, or use epoxy cement to inlay it. (Limited to a small number of joints and non-full-length or through joints)
4. When the cracks in the floor have a large area, a static load test should be carried out on the floor to check its structural safety. If necessary A layer of steel mesh can be added to the floor to improve the integrity of the slab. Or use epoxy resin liquid to seal the seams on the board surface (a layer of waterproofing is also acceptable), and paste carbon fiber cloth on the bottom of the board to form a tic-shaped shape, with the spacing being the same as the width of the cloth.
5. For long and penetrating dangerous structural cracks with a crack width greater than 0.2mm, the treatment method is as follows: in addition to cutting V-shaped grooves along the cracks and flushing them clean, fill the epoxy resin liquid with pressure In addition to sealing the internal joints, the floor slabs must also be reinforced with sticky flat steel or carbon fiber cloth. When reinforcing with carbon fiber cloth, for a single crack, in addition to pasting along the seam, it must be pasted at a spacing perpendicular to the seam direction; for multiple intersecting seams, it must be pasted in a tic-shaped pattern, with the spacing being the same as the cloth width. (The width of the cloth is about 300mm.)
6. When the total length, through-length and non-through-length, and through-length cracks are the same and there are many, the bottom of the board can only be pasted vertically and horizontally.