How to deal with the leakage of cracks in the concrete roof of the basement (causes and plugging methods)
Summary of causes of basement roof leakage
(1) Leakage caused by self quality and construction defects of waterproof concrete
According to the field survey, there are irregular shrinkage cracks at the bottom of the basement roof slab. Most of these cracks are caused by improper water cement ratio of concrete and untimely curing after pouring, and obvious water seepage occurs at the shrinkage position.
There are obvious defects and non dense areas in the concrete components of the basement roof, which seriously affect the overall impermeability of the concrete. According to the statistics of water leakage in the basement, the leakage locations are all penetrated into the basement through the weak parts of the concrete.
(2) Leakage caused by non-standard construction of post cast strip
The post cast strip is a rigid joint of concrete. Although this joint is simple in construction, it is still easy to cause leakage if not carefully constructed. First of all, the waterstop or tongue and groove joint shall be reserved in a very standardized way when the post pouring belt is reserved to meet the needs of the secondary joint of concrete. Secondly, the concrete of the post cast strip should be poured with shrinkage compensating concrete, whose impermeability and compressive strength should be one grade higher than the concrete on both sides Swelling agent And shall not be set again after pouring Construction joint To ensure its proper waterproof and impermeable performance.
(⑶ Poor drainage
One of the design principles of "prevention, drainage, interception and blocking" is "drainage". "Drainage" is very important. Only if the drainage is unobstructed, the chance of leakage will be greatly reduced. Therefore, drainage is an important shortcut for basement waterproofing and seepage resistance. However, during the inspection process, it was found that there was serious ponding on the roof of the basement, and the height of the ponding reached 7cm.
(4) Waterproof roll paste
According to the actual sampling, the self-adhesive waterproof coiled material and the base layer have large areas of hollowing and peeling, and the overlapping position of coiled material and coiled material is warped.
(5) Backfill on garage slab
The backfill is mixed with bricks, miscellaneous fill and construction waste. Large scale machinery was used for backfilling in large areas, instead of layered compaction and backfilling according to the construction specifications. The compactness of backfill soil was not enough, and a large amount of water accumulated in the backfill soil increased the erosion probability of the waterproof system.
How to deal with water leakage of concrete roof crack
1、 The waterproof layer of basement roof is cracked and leaking
1. Find out the setting position of the construction joint, and conduct waterproof treatment on the crack position. The specific method is: cut off the waterproof protective layer and polypropylene cloth waterproof layer within 800mm on both sides of the construction joint, clean up the exposed base layer cracks, adopt the method of post planting reinforcement on both sides of the crack position, and erect formwork to cast C25 reinforced concrete retaining wall of 300mm high and 250mm thick;
2. Adopt water solubility in the middle of retaining wall polyurethane Grouting materials shall be filled, and the cutting joints shall be sealed with water without missing sealant, and then paved ethylene Two layers of polypropylene composite waterproof coiled materials (one layer is required to be paved at the internal and external corners, and the middle groove of the retaining wall shall be filled with flexible materials after the bottom layer waterproof coiled materials are paved);
3. The waterproof layer of the retaining wall shall be externally bonded with 30mm thick rubber plastic insulation sponge and then covered with 5mm thick U-shaped steel plate for finished product protection (the steel plate shall have a butt weld every 2m, the weld shall be waterproof with self-adhesive 100mm wide waterstop, the surface shall be painted with one coat of antirust paint, and the mixed paint shall be painted twice for anti-corrosion). For the waterproof layer of the horizontal surface, the slope shaped C20 fine aggregate concrete protective layer shall be made.
2、 Leakage repair of basement roof crack
(1) Base course cleaning:
Remove the original materials and impurities of the expansion joint to the specified height (generally 7~10cm deep), and flush with water.
(2) Fixed grouting channel and grouting pipe:
Use quick plugging agent (liquid or powder) to mix ordinary Portland cement above 32.5 grade to fix the grouting channel PE foam strip. When fixing PE foam strip, one grouting pipe shall be buried every 50cm.
(3) Grouting plugging:
Inject macromolecular grouting material - grouting leak stoppers from the bottom. The grouting pressure should be controlled between 0.3 and 0.5MPa. When the grouting hole next to the grouting hole emits grout, stop grouting, close the valve, and then grout from another hole, and then proceed in sequence. After all grouting is completed, observe whether there is leakage. If there is still leakage in some places, supplement grouting from the nearest hole until there is no leakage.
(4) Cutting grouting pipe:
After 24h of grouting, if no leakage is confirmed, cut off the grouting pipe and dry the interface with a blowtorch.
(5) Clean the interface:
Use a wire brush to clean up impurities and skin debris generated during baking with a blowtorch.
(6) Construction flexible materials:
50~60mm thick PG321 two-component polysulfide sealant shall be applied in the joint, and T-shaped 300 mm wide and 20 mm thick two-component polysulfide sealant shall be applied externally.
(7) Make protective layer:
After curing of polysulfide sealant, use compression sealant as the next semi-rigid protective layer.
3、 Leakage repair of planting roof
Construction tools
Hammer, chisel, cable, movable support, mixer, cleaver, brush. Mixing bucket, etc.
Construction method
1) The crack shall be provided with a trench 2 cm deep and 2~3 cm wide.
2) The modified polyurethane waterproof coating is used to strengthen the cracks and protect the reinforcement in the concrete.
3) The trench shall be reinforced with osmotic crystallization quick drying agent (anti crack reinforcement quick drying agent).
