Wenshan Kang, Chris Tsai – CELOTECH
Water repellent agents are critical additives in cementitious materials, significantly improving the impermeability of mortar and reducing the water absorption rate of construction materials. These additives help protect building structures from moisture penetration, thereby enhancing durability, preventing mold formation, and ensuring long-term structural integrity.
CLASSIFICATION OF POWDERED SILICON-BASED WATER REPELLENT AGENTS
Silicon-based water repellent agents used in dry-mixed mortar can be classified into two main categories based on their surface treatment methods:
1. Encapsulated type: this type is obtained through spray drying, where active components are encapsulated with a water-soluble protective colloid and an anti-cracking agent. This structure enhances dispersion and efficiency in mortar applications.
2. Carrier-based type: in this method, inorganic materials serve as carriers, with active components attached to their surfaces. This formulation ensures effective integration with cementitious matrices, improving hydrophobic performance over time.
Both types of silicon-based water repellent agents exhibit distinct advantages in mortar applications, offering varying levels of water resistance, durability, and compatibility with cementitious materials.
MECHANISM OF HYDROPHOBICITY IN CEMENT MORTAR
During the mixing process, these organic silicon hydrophobic agents undergo hydrolysis in the highly alkaline environment generated by cement hydration.
The hydrophilic organic functional groups within the agents react to form highly active intermediates. These intermediates then undergo irreversible chemical bonding with hydroxyl groups in cement hydration products, ensuring their firm attachment to pore walls within the cement mortar structure.
The formation of Si-O-Si and Si-O-Ca bonds provides longterm hydrophobic effects, improving the durability of mortar by preventing water ingress even under prolonged exposure to moisture.
Additionally, the reaction of these active ingredients with calcium hydroxide (CH) in cement enhances their resistance to carbonation, further contributing to the stability and lifespan of the material.
As a result, the hydrophobic organic functional groups orient themselves toward the outer surface of the pore walls, creating a water-repellent barrier. This mechanism significantly reduces capillary water absorption, leading to enhanced hydrophobic performance in the final mortar application.
THREE CORE PRINCIPLES OF WATERPROOFING IN MORTAR
Waterproofing in cement-based materials is primarily achieved through the following three principles:
1. Surface Coating and Isolation: Creating a protective layer that prevents water infiltration.
2. Capillary Pore Blocking: Reducing the permeability of mortar by filling or modifying pore structures.
3. Surface Tension Enhancement: Increasing the surface energy to repel water penetration.
These principles can be applied individually or in combination to optimize water resistance in different construction scenarios. A well-formulated water repellent agent ensures that cement hydration remains unaffected while enhancing overall hydrophobic performance.
ADVANTAGES OF WATER REPELLENT AGENTS IN CEMENT MORTAR
Incorporating high-performance water repellent agents, such as Aquago® WP200H by Celotech, into mortar formulations provides the following benefits:
1) Improved waterproof properties: Enhances the hydrophobicity of mortar, preventing moisture ingress.
2) Reduced water absorption rate: Minimizes capillary absorption, prolonging material lifespan.
3) Enhanced dirt resistance: Helps maintain the aesthetic appearance of buildings by preventing dirt accumulation.
4) Increased durability: Protects cement-based structures from deterioration caused by water exposure.
5) Superior weather resistance: Strengthens resistance against environmental factors such as rain and humidity.
6) Minimized efflorescence formation: Reduces the migration of soluble salts, which can cause surface whitening and degradation.
7) Enhanced freeze-thaw resistance: Prevents damage due to cyclic freezing and thawing, crucial for structures in cold climates.
PERFORMANCE COMPARISON: AQUAGO® WP200H VS. MARKET ALTERNATIVES
A comprehensive study was conducted to evaluate the performance of the product against three other commercially available water repellent agents. The key parameters assessed included:
– water absorption coefficient (w-value) after multiple immersion cycles.
– Retention of compressive strength after prolonged water exposure.
– Effect on open time and workability in mortar applications.
The results demonstrated that mortar incorporating Aquago® WP200H exhibited:
– a 40% lower water absorption coefficient compared to the next best-performing competitor.
– A 30-degree higher contact angle, indicating superior hydrophobicity.
– Minimal reduction in compressive strength, confirming no adverse effects on mechanical properties.
– Extended open time and improved workability, enhancing ease of application in construction.
These findings underscore the superior waterproofing efficiency of Aquago® WP200H, making it an ideal choice for high-performance mortar formulations.
By integrating advanced silicon-based water repellent agents like Aquago® WP200H into construction materials, builders and manufacturers can achieve enhanced waterproofing, improved structural longevity, and optimized performance for modern building applications.
