Comparison between water-swelling waterstops, rubber waterstops, and waterstop steel plates:
After using waterstops (waterstop steel plates, waterstop strips), you can It prevents water from soaking into the concrete and plays a dual protective role of waterproofing and water-stopping.
Water-swelling waterstops, rubber waterstops, and waterstop steel plates can theoretically effectively prevent external moisture from penetrating concrete through construction joints. From the analysis of waterstop principles and construction techniques, the three There is still a big difference, and the effects are also different. Taking the three-story underground structure of a certain project as an example to analyze the advantages and disadvantages of using the three in different parts.
Water-stopping principle: Water-stopping strips absorb water and swell, then squeeze closely with the concrete and block the gaps to stop water.
Construction technology: The water stop strips are square and long strips, and the parallel overlap method is used when connecting, without leaving any break points in the middle. For convenience, construction units often like to use waterstop strips. When the concrete pouring is completed, they can be pressed on the surface of the wall concrete pouring or reserve grooves for secondary inlays.
Analysis of advantages and disadvantages: The construction is simple, the investment is relatively small, and it is relatively economical. However, the water-stopping effect is not as good as waterstop tape and waterstop steel plate. There are many unforeseen problems during the construction process. First, the steel bars are not placed densely. Second, if the time is too long, it will absorb moisture and expand, affecting the effect. Especially in the rainy season, when the air humidity is high and there is a lot of rain, the water-stopping effect is even worse. Third, the construction joints are uneven and have poor contact. Usually this method is not very effective in stopping water. For example, if the grooves left during the installation of waterstops are too large, they cannot be effectively fixed, and if they are too small, they cannot be inlaid in place. When concrete is poured, they are easily displaced under the buoyancy of the concrete.
Scope of application: It can be used in buildings without underground water. It is generally used in secondary parts of buildings or parts with loose requirements, such as basement exterior walls above the groundwater level, foundation rafts, etc., that is, mainly Prevent capillary water in the soil layer. Even if there is water leakage, it will have little impact on the building and can be quickly solved with waterproof materials such as leak-stopping spirit. However, it is not suitable to be used on the roof of an underground garage with covering soil or planting soil on the surface.
2. Water-stopping steel plate
Water-stopping principle: The "opening" of the water-stopping steel plate faces the oncoming side, and the steel plate and the concrete are closely combined. Supplemented by the eight-figure shape of the steel plate, it is difficult for groundwater to flow along. The construction joints are soaked from the steel plate.
Construction technology: The thickness of the water-stop steel plate is generally 3mm, the width is >200mm, and the length is generally processed into 3 meters or 6 meters long. Generally, three meters is easy to transport. During construction, try to ensure that the water-stopping steel plate is on the center line of the wall; the welding between the two steel plates must be full and double-sided
, and the overlap of the steel plates should be no less than 200mm. The corners of the wall are usually treated by bending the entire steel plate, T-shaped welding, 7-shaped welding, etc. For the support welding of the water-stop steel plate, small steel bars can be used to be electrically welded to the main bars; when the water-stop steel plate passes through the column stirrups, the stirrups passed through can be disconnected and made into open hoops, which are electrically welded to the steel plate.
Analysis of advantages and disadvantages: The connection parts of the steel plate waterstops need to be fully welded. The effect is of course very good, but the cost is much higher and the construction speed is relatively slow. The specification requires that for shear walls using water-stopping steel plates, the thickness of the wall should not be less than 250mm. The net distance between the water-stopping steel plates and the steel bars is: wall thickness/2-thickness of the outer protective layer 50-diameter of the two-way steel bars of the wall; when the wall When the thickness is 250, 250/2-50-30=45㎜. The distance between the water-stopping steel plate and the wall is too small. During construction, the concrete in this area is prone to vibration leakage and honeycomb holes are formed. Therefore, when using water-stop steel plates, vibration must be strengthened at the construction joints. The weak links of this water stop measure are the overlapped parts and the 90° corner parts. The welding seam at the 90° corner of the steel plate is extremely difficult to control and can easily cause leakage points. The welding construction of the corner parts of the steel plate should be controlled as a key part of the process.
Scope of application: Applicable to structures with groundwater, such as pools and other buildings with water, as well as horizontal and vertical construction joints buried deep below the groundwater level.
3. Rubber waterstop
Waterstop principle: Waterstop is a strip made and installed to prevent moisture penetration,
Width 200- 350, selected according to the design, the seepage path is appropriately extended, and it is partially or completely buried in the concrete during the concrete pouring process. It has a certain strength and toughness, and its strength and toughness are between waterstop strips and waterstop steel plates.
Construction technology: Methods for fixing waterstops include additional steel bar fixing, special clamp fixing, lead wire and template fixing, etc. When perforation is needed, it can only be installed at the edge of the waterstop and other parts must not be damaged. When on-site connection is required, electric heating plate vulcanization bonding or cold bonding (rubber waterstop) or welding (plastic waterstop) methods can be used. During the construction of the waterstop, it is not allowed to be exposed to the sun for a long time, prevent rain, and do not come into contact with highly polluting chemicals; during transportation and construction, prevent machinery and steel bars from damaging the waterstop; during the construction process, the waterstop must be reliably fixed , avoid displacement when pouring concrete, and ensure the correct position of the waterstop in the concrete;
Pros and cons analysis: There are many sharp stones and sharp steel heads in concrete, because of the plastic and rubber The tear strength is 3 to 5 times lower than the tensile strength. Once the waterstop is punctured or torn, the crack will expand without a lot of external force. Therefore, during the positioning of the waterstop and the concrete pouring process, you should Pay attention to the positioning method and pouring pressure to prevent the waterstop from being punctured and affecting the waterstop effect.
During the concrete pouring, since the waterstop is made of rubber and is relatively soft, it is easy to deform, is not straight, and the upper and lower widths are difficult to control. If lead wire is used to tie the steel bars, the waterstop will be damaged, so the construction Work units generally find it troublesome and don't like to use it.
Scope of application: This water-stop material has good elasticity, wear resistance, aging resistance and tear resistance, strong adaptability to deformation, good waterproof performance, and a temperature range of -45℃～+60 ℃.
The selection of the waterstop should be determined based on comprehensive considerations such as the importance level of the structure, the amount of deformation and water pressure of the deformation joints, the working environment for the use (application) of the waterstop, and economic factors. It is generally used for vertical water-stopping of waterproof parts, such as construction joints or post-casting belts or settlement joints, expansion joints of board wall structures and other places with large settlement deformation.
IV. Conclusion
Through analysis and comparison, it is found that among the three water-stopping measures, water-stopping strips are cheap, easy to construct, and have the worst water-stopping effect. They are generally used for groundwater levels. The above secondary waterproofing parts; water-stopping steel plates are the most expensive, the most difficult to construct, and have the best water-stopping effect. They are generally suitable for vertical and horizontal construction joints below the groundwater level. Because they are too rigid, they are not suitable for use in parts with large deformations. The price, performance, and construction difficulty of waterstops are between waterstop strips and waterstop steel plates. They have a wide range of applications. Because of their high toughness, they are more suitable for use in areas with large deformation and settlement deformation requirements.