Waterproof coatings are materials used to prevent water penetration and are widely used in buildings, bridges, tunnels, basements, and other areas. With technological advancements, the variety of waterproof coatings continues to grow, and each type plays an important role in different environments and conditions. This article will discuss the main types of waterproof coatings and their uses in detail.
Chapter 1: Rigid Waterproof Coatings
Rigid waterproof coatings form films that are hard, but lack flexibility. They primarily achieve waterproofing and anti-seepage properties by reacting their active chemical components with the concrete base or by solidifying themselves into a dense structure.
Main Types and Characteristics:
1. Cement-Based Penetrating Crystallizing Waterproof Coatings
Working Principle: The active chemical substances contained in these coatings, in the presence of water, penetrate the pores and microcracks within the concrete, reacting with cement hydration products to form water-insoluble dendritic crystals, effectively blocking the pores and making the concrete denser. A notable feature is that when water seeps through new cracks in the concrete, the remaining unreacted substances are reactivated, enabling “self-healing.” Key Features: High permeability, self-healing ability, water pressure resistance, excellent adhesion to the concrete base, and a waterproof layer with a lifespan equal to the structure.
Main Applications:
Large dams, reservoirs, sewage treatment tanks, etc.; underground tunnels, subways, underground garages, civil air defense projects, etc.; indoor kitchen and bathroom floors and walls, especially suitable for areas that will require subsequent tiling.
2. Polymer Cement Waterproof Mortar
Working Principle: Made from a mixture of cement, fine aggregate, and a high-molecular polymer emulsion. The polymer forms an elastic membrane within the mortar, interwoven with the cement hydration products, significantly improving the brittleness of ordinary mortar and enhancing its adhesion and impermeability.
Key Features: High compressive strength, aging resistance, strong adhesion, and environmentally friendly and non-toxic.
Main Applications:
Waterproofing and anti-seepage for building exterior walls; moisture-proofing for basement walls and floors; waterproof lining for swimming pools and water tanks; and as a base for tile laying, achieving “integrated waterproofing and tiling” construction.
Summary of Rigid Waterproofing Systems: Their advantages lie in their high strength, puncture resistance, and durability, and they can be applied directly to cement mortar plastering or tile laying after application. However, their critical weakness is their inability to resist expansion and cracking of the base layer. Once new cracks develop in the structure, the waterproofing layer will also crack and fail. Therefore, they are more suitable for new buildings with stable structures and minimal deformation, or for indoor moisture-proof environments.
Chapter 2: Flexible Waterproofing Coatings
Flexible waterproofing coatings form coatings with excellent elongation, elasticity, and crack resistance, adapting well to minor cracking and displacement of the base layer. They are currently the most widely used type in home improvement and construction projects.
Main Types and Features:
1. Polymer Emulsion Waterproofing Coatings (Acrylates)
Working Principle: A high-molecular-weight acrylic emulsion is the primary film-forming substance, forming a film through water evaporation and the fusion of emulsion particles. This is a single-component, water-based coating.
Key Features: Environmentally friendly, non-toxic, pollution-free, easy to apply, good breathability, strong adhesion, and adjustable color (usually white or gray).
Main Applications:
Indoor kitchen and bathroom waterproofing; exterior wall waterproofing and decoration with some UV resistance; lightweight roof waterproofing, suitable for roofs with steep slopes and low water accumulation.
2. JS Polymer Cement-Based Waterproofing Coating
Working Principle: This two-component coating consists of a polymer emulsion and a powdered material such as cement. It combines the durability of rigid materials with the elasticity of flexible materials. By adjusting the ratio of liquid to powder, a coating with varying degrees of flexibility can be achieved.
Key Features: Combining rigidity and flexibility, extremely high bond strength, easy application, and environmentally friendly.
Main Applications:
Comprehensive home waterproofing, suitable for most home decoration applications, including kitchens, bathrooms, balconies, and basement walls and floors; waterproofing of non-exposed roofs and basements; and waterproofing of swimming pools and pools.
3. Polyurethane Waterproofing Coating
Working Principle: This one- or two-component coating is made from a polymerization reaction of isocyanates and polyethers, followed by the addition of fillers and additives. The resulting coating is tough, elastic, and has excellent overall performance. Key Features: Extreme elongation, high elastic recovery, excellent water resistance, abrasion resistance, and corrosion resistance. Single-component coatings cure via air humidity, while two-component coatings require a specific mixing ratio for curing.
Main Applications:
Areas with high deformation requirements: Complex joints such as structural expansion joints, pipe roots, and internal and external corners; Environments with long-term water immersion: Basement floors, swimming pools, reservoirs, bridges, etc.; High-performance roof waterproofing.
4. Polyurea Waterproofing Coating
Working Principle: This coating can be considered an upgraded version of polyurethane, formed by the reaction of an isocyanate component and an amino compound component. Its extremely fast reaction rate allows for instant curing without a catalyst.
Key Features: Ultra-high physical properties (strength, toughness, and abrasion resistance), excellent weather resistance (UV resistance, cold and heat resistance), 100% solids content (zero volatiles, zero VOC), seamless, thick coating capability, and rapid drying.
Main Applications:
Extreme environments and high-grade projects: High-speed rail, subway tunnels, water conservancy facilities, and chemical corrosion-resistant flooring.
High-performance roofs and stadium stands: Can withstand direct outdoor exposure and have a long lifespan. Water parks, wave pools, and other recreational facilities: Wear-resistant, non-slip, and colorful.
Summary of Flexible Waterproof Systems: The core value of flexible coatings lies in their ability to effectively address stresses caused by building settlement and thermal expansion and contraction. Selection should be based on a comprehensive assessment of the expected deformation of the base layer, environmental exposure conditions, and environmental requirements.
Chapter 3: Specialty Waterproofing Coatings
1. Rubber Asphalt Waterproofing Coating
Features and Applications: This coating uses specialized spraying equipment to form a dense, high-strength, high-elongation waterproof layer. Seamless and highly effective, it is particularly suitable for irregular structures, large-scale construction, and emergency repair projects.
2. Waterborne Epoxy Waterproofing Coating
Features and Applications: It combines the high strength, hardness, excellent adhesion, and chemical resistance of epoxy resin with the environmental advantages of waterborne coatings. It is primarily used for waterproofing and protecting industrial floors, food factories, and pharmaceutical plants where high strength and corrosion resistance are required.
3. Metal Roof Waterproofing Coatings
Features and Applications: Typically acrylic or fluorocarbon systems, these coatings offer strong adhesion, excellent weather resistance, elasticity, and rust resistance. They are specifically designed to address leaks in joints and screw holes on metal roofs made of pre-painted steel.
Faced with the diverse world of waterproofing coatings, the following principles should be followed when selecting:
Environment: Determine whether the application is indoors or outdoors, whether it is facing or facing water, and whether it is subject to chronic water immersion or intermittent moisture.
Substrate: Determine whether the substrate is stable concrete, easily vibrating metal sheeting, or a lightweight wall that may crack.
Deformation: Assess whether the structure is at risk of settlement, expansion, or vibration. For high risk, choose a flexible coating (such as polyurethane or JS); for low risk, choose a rigid or rigid-flexible coating.
Environmental Protection: For indoor and drinking water pools, choose an environmentally friendly and non-toxic water-based coating (such as acrylic, JS, or water-based epoxy).
Applicability: For complex joints, choose a coating that is easy to apply and has strong adhesion (such as JS or polyurethane). For large, flat surfaces, consider high-efficiency spray coating.
In short, waterproofing is a systematic project. Excellent materials are only the foundation. Standardized base layer treatment, meticulous joint treatment, a suitable coating thickness, and proper maintenance all contribute to a flawless, watertight defense. Understanding the characteristics and strengths of each waterproofing coating is the starting point for achieving this goal.
Post time: Oct-15-2025