What is the waterproof performance of the shaft type multi-directional displacement comb plate expan
The shaft type multi-directional displacement comb plate expansion device adopts a composite multi-layer waterproof system, relying on the gap sealing of the comb plate, the lower rubber waterproof layer, and the collection and drainage structure to achieve water stop, while also having the ability to self clean slag; It can adapt to multi-dimensional displacement conditions such as longitudinal e
The shaft type multi-directional displacement comb plate expansion device adopts a composite multi-layer waterproof system, relying on the gap sealing of the comb plate, the lower rubber waterproof layer, and the collection and drainage structure to achieve water stop, while also having the ability to self clean slag; It can adapt to multi-dimensional displacement conditions such as longitudinal expansion, lateral displacement, and vertical rotation, and protect the concrete, steel bars, and supports at the beam end from rainwater, snowmelt, and salt erosion.
1、 Basic components of waterproof system
Surface sealing: Inject waterproof sealing grease into the gaps between the teeth to seal the gaps and prevent most of the surface water on the bridge deck from directly infiltrating.
Main waterproof layer: A chloroprene rubber/EPDM rubber waterproof layer (double-layer rubber waterproof) is laid under the comb plate as the core waterproof barrier; When the shaft displacement hinge rotates with the beam end, the rubber waterproof layer adapts to the deformation and will not tear or fail directly due to multi-directional rotation.
Stainless steel skateboard cushion layer: arranged above the rubber waterproof layer to isolate sand, gravel, and debris, reduce direct wear of the rubber layer by debris, and protect the service life of the waterproof layer.
Drainage structure: Water seepage can be discharged along the waterproof layer to both sides, without directly accumulating in the gaps at the beam ends; Partially optimized products are equipped with water collection and drainage channels to divert a small amount of seepage water to the side of the beam for discharge, in order to prevent water accumulation from soaking the supports.
Structural advantage: The comb teeth gap is arranged on the side of the beam end, and debris can be automatically discharged by vehicle rolling and expansion movement, reducing the probability of slag accumulation, squeezing, and puncturing the waterproof layer, and reducing the risk of the waterproof system being damaged by hard objects.
2、 Waterproof performance under actual working conditions (advantages)
Suitable for multi-directional displacement sealing: Different from ordinary comb plates, the hinge of the shaft can absorb vertical angles and lateral offsets, and the rubber waterproof layer will not be forced to pull or crack due to beam end warping or misalignment. Its waterproof reliability is better than that of ordinary one-way comb expansion devices on curved bridges, inclined bridges, and large-span flexible bridges.
Multiple defenses and graded waterproofing: The first barrier is the tooth joint sealant, and the rubber waterproof layer is responsible for the main anti-seepage. A small amount of water seepage is led out by the drainage structure, rather than relying on a single sealing element for waterproofing, reducing the risk of direct leakage caused by single point failure.
Shallow buried structure for easy maintenance and replacement: The waterproof rubber layer is a modular component that does not require large-scale chiseling of the beam concrete. Local damage can be repaired and replaced in sections, without the need to replace the entire expansion device as a whole.
3、 Shortcomings and common causes of failure in waterproofing systems (actual pain points in engineering)
The comb plate is not completely "zero leakage", and a small amount of water seepage is inevitable. Most of the diseases come from material aging, construction, and operation.
Aging of sealing oil paste: The surface waterproof oil paste will harden, crack, and peel off due to long-term exposure to sunlight, vehicle rolling, and high and low temperature cycles. There will be channels in the gaps between teeth, and surface water will penetrate downwards. The ointment is a consumable item and needs to be refilled regularly.
Rubber waterproof layer aging and damage: UV rays, melting salt erosion, sand and gravel wear, rubber will harden and crack; If the rubber overlap is not tight and the flipping height is insufficient during installation, local water leakage may occur; The repeated displacement of the shaft makes the rubber bending part more prone to fatigue cracking.
The construction quality is greatly affected: the steel fiber reinforced concrete in the anchorage zone is not compacted properly, the joint surface between new and old concrete cracks, and rainwater seeps through the gaps in the concrete by bypassing the waterproof layer. This fault does not belong to the damage of the waterproof components of the expansion device body, but is manifested as water seepage at the beam end.
Accumulation of debris indirectly damages waterproofing: Although it has the ability to self clean slag, a large amount of sediment and asphalt fragments will still remain, squeezing and puncturing the rubber waterproof layer, causing leakage.
4、 Key conditions for improving waterproof durability
Rubber component selection: chloroprene rubber is selected in cold regions, and EPDM rubber is preferred in high temperature and rainy regions to improve aging resistance and salt corrosion resistance.
Construction control: Ensure the overlap width of the rubber waterproof layer and the height of the beam end flipping up; The concrete in the anchorage zone is compacted to block the infiltration channel.
Daily maintenance: Regularly clean the debris in the comb teeth gap, check the condition of the grease, and timely replenish it if it ages or cracks; Regularly check whether the rubber waterproof layer is torn, and promptly repair any local damage found.
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