1. Technical field: The utility model relates to a water-swellable rubber water-stop ring used on a formwork opposing bolt, belonging to a special fitting for supporting concrete formwork in construction engineering.
2. Background: In the traditional formwork support of concrete wall, the opposite bolt or batten pull rod (hereinafter referred to as the opposite pull ring) is the main connector to pull the internal and external formwork. Its function is to keep the spacing and shape of the internal and external formwork, resist the lateral pressure of cast-in-place concrete and other loads on both sides of the formwork, and ensure that the formwork has sufficient stiffness and strength. At present, the most common specifications of tension bolts in China are M8, M 10, M 12, M 14, M 16, etc. (made of round steel with threads at both ends), the common specifications of the pull ring are narrow-band steel belts with a width of 30~60mm and a thickness of 0.75 ~ 2.5 mm, but in waterproof concrete construction with waterproof requirements, such as various underground buildings, basements, foundation projects, tunnels, water conservancy, civil air defense projects, water storage structures, municipal water supply and drainage projects, etc. Because thousands of counter-bolts used to fix formwork penetrate the wall, gaps are formed between the counter-bolts and the surrounding concrete, resulting in many seepage channels, thus losing the waterproof function of waterproof concrete itself (the national design and construction standards clearly require underground engineering and water storage). In order to solve this problem, a steel plate with a thickness of 2~3mm and a thickness of 80mm×80mm is welded between the counter-bolts at present, and the purpose of stopping water is to increase the infiltration by changing the seepage path of pressure water and extending the infiltration line. The main disadvantage of this method is that the steel plate needs to be cut, drilled, then fixed with bolts, fixed in the middle position, and then completely welded around the bolts. Especially the weld quality is difficult to check and ensure. Once cracks, slag inclusion, burning through, needle-like pores and other defects appear in the weld, future seepage paths will be generated, which is difficult to cure. This problem has not been well solved in the field of civil construction for many years.
3. Mechanism and application: In view of the above shortcomings, a water-swellable rubber water-stop ring is provided, which is simple in structure and convenient to use, and is sleeved on the opposite bolt or the opposite pull tab of the template. The rubber water stop ring body is made of rubber which swells when meeting water, and can be a circular sheet body. The opening in the middle position should be made into a round hole or cut into a long slit running through both sides according to whether it is used on the opposite bolt or the opposite pull ring (see figure 1). The thickness of the water stop ring is 7 ~ 20mm, and the diameter or side length is 30 ~ 80mm. The commonly used specification is PZ type, which is a rubber ring with the outer diameter D=40mm and the thickness h= 10mm, and the diameter of the middle hole is 2mm smaller than that of the directional bolt (the overall size, ring body thickness or the number of rings used on each bolt are adjusted according to the head height). When in use, the water stop ring can be tightly sleeved in the middle of the opposite bolt or the opposite pull tab (see Figure 2), and finally buried in the cast-in-place concrete. When the building is in use, if there is pressure flowing along the bolt gap on one side (this is inevitable due to the drying shrinkage of concrete itself), when it meets the rubber water stop, the water stop absorbs water and expands, forming an impermeable plastic colloid, blocking the surrounding seepage channel and stopping water.
Four. Advantages of the product:
1. Simple structure, convenient construction, no need for professional technicians and equipment, good water-stopping effect, no pollution, no toxicity and corrosion resistance, which can speed up the construction progress and greatly reduce the comprehensive construction cost.
2. rubber strip, made of similar materials and water-swellable rubber, has been widely used in waterproof sealing of various projects. Like its twin brother, this water-stop ring has the same effect. It is a polymer waterproof material with official national standards. This rubber gradually absorbs water and expands when it meets water. It can pass repeated immersion test and its durability is reliable. After many engineering practices, the effect is very good. All the indexes of this material meet the requirements of GB/T 18 173.3—2002 Part III (Water-swellable rubber). The maximum expansion rate can reach 300%. The expansion rate of this rubber in alkaline solution is very low, so there is no need to worry about excessive expansion before concrete sets.
3. The working principle is simple, the visibility is strong, and it is easy to be understood and accepted by designers, supervisors, owners and construction engineers, and it is easy to popularize.
4. This product has a sufficient basis for engineering use. Refer to Figure 5.3.3-2 of GB/50 108-200 1 Technical Specification for Waterproofing of Underground Engineering for the recommended use.
5. The domestic authoritative magazine "Building Technology" published this patented technology in the 8th issue of 2003.
It should be noted that before transporting, storing and pouring concrete, it is forbidden to soak in water and get caught in the rain for a long time. "Water-swelling rubber sealing ring for formwork-to-bolt" will certainly play an important role in improving the construction quality of waterproof concrete in the building field.