As a core component of modern drainage systems, the sealing performance of PC gutter board at its connection with the surrounding concrete structure directly affects the overall waterproofing performance and durability of the project. To ensure efficient sealing at the joints, a comprehensive approach is needed, encompassing material selection, structural design, construction techniques, and post-construction maintenance, to create a systematic leak-proof solution.
Regarding material selection, the sealing material at the interface between the PC gutter board and the concrete must possess excellent weather resistance, chemical corrosion resistance, and elastic recovery. Because drainage systems are constantly exposed to humid environments and may come into contact with corrosive substances such as acids and alkalis, traditional sealing materials are prone to aging and cracking, leading to leaks. Therefore, modified silane sealants or polyurethane sealants are recommended. These materials have stable molecular structures and high main chain bond energy, effectively resisting the effects of ultraviolet radiation, ozone, and temperature changes. They also exhibit strong adhesion to concrete and PC materials, forming a durable sealing barrier. Furthermore, the sealing material must possess low modulus characteristics, meaning it can absorb stress through its own deformation under load, preventing interface debonding caused by concrete shrinkage or temperature changes.
In terms of structural design, the connection between the PC gutter board and concrete requires a dual protection system of "structural waterproofing + material waterproofing." Structural waterproofing is achieved by optimizing the joint shape, such as using tongue-and-groove joints, uneven joints, or stepped joints, utilizing a tortuous path to extend the seepage route and reduce the water pressure on the sealant. Simultaneously, drainage channels or holes are installed at the bottom of the joints to guide small amounts of seeping water to the drainage system, preventing long-term immersion of the sealant in water. Material waterproofing relies on the filling and bonding of the sealant. It is essential to ensure that the joint width and depth meet design requirements; generally, the joint width should not be less than 10mm, and the depth should be 0.5 to 0.7 times the width to ensure sufficient sealant filling and bonding area.
The construction process is a crucial step in ensuring a tight seal. First, the contact surface between the PC gutter board and the concrete must be thoroughly cleaned to remove oil, dust, and loose particles. If necessary, sandblasting or grinding should be used to increase surface roughness and improve the sealant's adhesion. Secondly, before applying the sealant, a primer should be applied to the bottom and sidewalls of the joint to enhance the compatibility between the sealant and the substrate. During sealant application, a dedicated caulking gun should be used to fill the sealant evenly, ensuring no air bubbles, voids, or breaks, and creating a smooth concave surface to facilitate drainage. For wide or dynamic joints, a backing material can be embedded to prevent cracking caused by three-sided adhesion of the sealant.
During concrete pouring, measures must be taken to protect the PC gutter board from mechanical damage. For example, traffic strips should be laid on both sides of the drainage ditch to prevent direct vehicle traffic; layered vibration should be used during pouring to prevent concrete segregation and porosity; a release agent or release film should be applied to the contact surface between the drainage ditch and the concrete to facilitate later demolding and joint treatment. Furthermore, the concrete must be cured promptly after hardening to prevent shrinkage cracking that could affect the sealing effect.
Given the thermal expansion and contraction characteristics of concrete, expansion joints should be installed at the joints or reinforcement measures should be used. Expansion joints can disperse stress caused by temperature changes, preventing cracking of the concrete at the joint and thus preventing seal failure. Reinforcement enhances the tensile strength of concrete and inhibits crack propagation. However, it's crucial to ensure a release layer between the reinforcing steel and the sealant to prevent corrosion of the steel and its potential damage to the sealant.
Post-construction maintenance is equally important. After the PC gutter board system is put into use, the joint seals must be checked regularly, blockages removed, and any damage repaired. For drainage systems exposed to harsh environments for extended periods, a comprehensive inspection should be conducted every 5 years, using infrared thermography or seepage tests to assess sealing performance and promptly replace aging sealant.
Ensuring the airtightness of the PC gutter board within the surrounding concrete structure requires continuous attention throughout the design, construction, and maintenance phases. Through scientific material selection, meticulous design, standardized construction, and regular maintenance, an efficient leak-proof system can be built, extending the service life of the drainage system and providing reliable protection for building projects.
