Looking at rural houses, due to the influence of construction, geological changes and temperature changes, there will be general wall cracks of different shapes and directions in the corners of the wall, on the wall under the girder, between the windows, and at the junction of the partition wall and the longitudinal wall. Because these cracks will not have a great impact on the safety of the housing structure in the early stage of development, but with the continuous development of these cracks, it will bury many quality hazards for the structural safety of the house. To this end, it must arouse the great attention of rural construction personnel and homeowners. The cause of the crack should be identified, and it is necessary to observe whether the crack continues to develop, and then treat it in combination with the characteristics of the corresponding crack.
(1) Treatment of oblique cracks caused by the settlement of the foundation
All kinds of cracks caused by uneven settlement of the foundation should be remedied according to the following technical measures:
1. When the cause of settlement is found, a note should be pasted across the middle of the crack, or a plaster cake should be pasted to observe the development of the crack. If the crack is no longer developed, it can be treated.
2. If the foundation settles due to pressure water or drainage pipe leakage, it must wait until the moisture content in the foundation is less than 8% before construction.
3. Use the Luoyang probe shovel to drill holes at 500mm outside the foundation, if the width of the crack is not very large, the length is short, it can be outside the foundation; if the seam width and seam length are large, the holes can be drilled on both sides of the indoor and outdoor foundation. The hole should be diagonally toward the bottom of the foundation and beyond the bottom of the cushion. The pore diameter should be 200mm, and the hole spacing should be determined according to the severity of the crack.
4. In order to prevent the impact of the hole on the foundation, the method of hitting one by one can also be used. After the hole treatment is completed, the unpunished hole is punched and processed.
5. Process the quicklime block into small pieces with a diameter of 50mm (no lime powder or less than 50mm), fill the holes in layers, fill the gaps of the lime block with dry sand for each 300mm, and then pound the iron rod, and then fill the upper layer.
6. When the filled lime block is 500mm from the ground, the upper part is sealed with c20 strength grade concrete. After such treatment, the quicklime block produces volume expansion after absorbing water underground, forcing the soil under the foundation to be squeezed, and generating an upward lifting force, lifting the settled wall up so that the crack is controlled. This effect is best for the foundation to sink after the foundation seeps water. There is also a method that is more effective for houses with earthen girders. This method is to add a lifting beam to the settlement part of the foundation. The distance of the additional lifting beam should be determined according to the degree of settlement, and then treated with quicklime blocks.
(2) Treatment of vertical cracks under concrete beams
When vertical cracks are generated in the wall under the concrete beam, it is obvious that the wall is formed by the small cross-section and low compressive strength. In this way, it is necessary to increase the pressure area of the bottom of the beam to solve.
1. Remove all loads on the floor.
2. Set up a pier foundation at the bottom of the beam, and the area of the foundation should be determined according to the weight of the beam and floor. The corresponding tonnage jack is then placed on the pier and directly topped at the bottom of the beam. The upper part of the jack should be paved with steel plates, and the thickness shall not be less than 20mm.
3. The jack will be gradually lifted, and stopped when the beam moves slightly, at this time, a support or lifting beam can be set up under the beam to tighten the top of the beam.
4. The bricks in the lower part of the beam are chiseled off, and the width and thickness should be determined according to the length or thickness of the added beam pad.
5. Water the top surface of the chiseled wall, flush out the chiseled broken bricks or mortar blocks, spread the cement mortar, and stuff the pre-prepared beam pads into it. Then use the inclined iron to press tightly into the bottom surface of the beam.
6. After the oblique iron is laid, the support or lifting beam is removed and the treatment is completed.
For vertical cracks in the bottom of the beam, there is also a method of adding concrete pilasters. This method is carried out without affecting the indoor use area and use function.
When adding pilasters, concrete should be poured after reinforcement according to normal reinforcement, in order to ensure the interconnection between the pilaster and the original wall, the expansion bolts are installed on the wall every 500mm, and two are installed on each layer, with a diameter of not less than 16mm. Stopped when concrete was poured to the bottom of the beam 200mm. After the strength of the concrete reaches 70%, a special support bolt is used to support the bottom of the beam and the pilaster surface, and then the remaining concrete is poured. At this time, because the vibrator cannot be used, it is manually pounded from the outside mouth to the inside. The re-poured concrete should be dry and hard. When the concrete strength reaches 100%, it can be put into use.
(3) Treatment of cracks in the wall
For the various cracks generated on the wall, it not only affects the role and bearing capacity of the wall, but also has a great impact on the apparent quality of the wall. Therefore, when the cracks generated have been fundamentally treated, the cracks on the wall should be treated to achieve the overall effect of completing the damageless wall.
1. Before dealing with cracks, the material of the wall should be fully understood, and then the material of the seam repair should be determined according to the original material. If it is an ordinary brick, cement mortar is applied.
2. Use a small handheld cutting machine to cut the seam along the edge of the crack 30mm to form a narrow triangle gap within the width of the face, and the depth should be 20mm.
3. Rinse the incision with water and ensure that the brick at the incision absorbs water to a depth of 20mm.
4. First use cement slurry to spread a layer on the cut incision, and cement slurry can also be used if conditions permit. Then the mixed patching mortar is embedded in the incision with a sharp trowel, and the mortar is firmly bonded with the bonding layer of the plain pulp, and the thickness of each plastering mortar is 10mm. Each plaster is only compacted and not smeared. The second plaster is to be plastered 24h after the first plaster.
5. When smearing the ash of the second pass, a layer of cement slurry binding layer is also smeared on the surface of the first plaster, and then the plaster is plastered. When smearing the ash for the second time, it should be slightly higher than the wall surface by 3mm, and then use the scraping ruler to scrape off the high sand ash to ensure that the seam ash is flush with the wall, and then use an iron trowel to collect the light.
6. If the crack of the wall surface is wider or longer, the cut ash mouth should also be increased accordingly, the widest can be cut to 50mm, and the old mortar at 40mm outside the cut is all removed, and the seam ash can be patched to the wall surface, and a fiber cloth can be pasted along the seam, and then the surface layer ash can be smeared on it, and the original plaster surface is flush to ensure the integrity of the crack and the redevelopment of the control crack.
For larger seams, after the incision is completed, it is possible to inject glue mortar into the seam first, and then fill the seam and wipe the surface, so that the effect is better. For the treatment and treatment of wall cracks, we must combine the local architectural design units, and then treat them according to the actual situation of the cracks after coming up with a scientific treatment plan, and do not blindly carry out the treatment, so that the crack accident worsens and causes quality accidents.