What Is A Concrete Sealer?
A concrete sealer is a protective coating or treatment applied to concrete surfaces to enhance durability, prevent deterioration, and improve resistance against various environmental factors. It acts as a barrier, sealing the pores and capillaries within the concrete, thereby reducing water and chemical penetration.
Different Types of Concrete Sealers
- Penetrating Sealers: These sealers, such as silanes, siloxanes, and siliconates, penetrate into the concrete and chemically react with the substrate, forming a hydrophobic barrier within the pores. They allow the concrete to breathe while providing protection.
- Film-Forming Sealers: These sealers, like acrylics, epoxies, and polyurethanes, form a protective film or coating on the concrete surface, creating a physical barrier against water and chemicals.
- Reactive Sealers: These sealers, such as sodium silicates and crystalline admixtures, react with the concrete’s free lime and moisture, forming insoluble crystals that block the pores and capillaries from within.
How to Choose Concrete Sealers?
Sealer Composition and Mechanism
Concrete sealers can be broadly classified into film-forming and penetrating types. Film-forming sealers like epoxies, acrylics, and urethanes form a protective coating on the surface while penetrating sealers like silanes, siloxanes, and silicates penetrate into the concrete pores and react with the cement matrix. The choice depends on the desired level of breathability and water repellency.
Performance Requirements
Key performance criteria include water absorption reduction, chloride ion penetration resistance, freeze-thaw durability, UV resistance, abrasion resistance, and bond strength to concrete. Sealers should also maintain skid resistance for concrete pavements.
Concrete Properties
Sealer performance is influenced by concrete properties like water-cement ratio, air entrainment, curing method, and age. High-quality, well-cured concrete generally benefits more from sealers. Pozzolanic materials like fly ash can also impact sealer effectiveness.
Application and Service Life
Ease of application, drying time, reapplication frequency, and cost are practical considerations. Service life depends on factors like UV exposure, abrasion, and chloride exposure conditions. Compatibility with existing concrete conditions (e.g., moisture, cracks) is also important.
Environmental Impact
Solvent-based sealers release VOCs, while water-based formulations are more environmentally friendly. Renewable, bio-based components like vegetable oils and tree rosins can further reduce the environmental footprint.
In summary, the selection of a concrete sealer involves evaluating its composition, performance characteristics, compatibility with the concrete substrate, application requirements, service life, and environmental impact to meet the specific project needs.
Applications of Concrete Sealers
Surface Protection
Concrete sealers are primarily used to prevent water ingress and protect concrete surfaces from deterioration, cracking, and other damage caused by moisture penetration. They form a protective barrier against water, chloride ions, aggressive liquids, atmospheric gases, and pollutants. Sealers can also improve the aesthetic appearance of structures.
Concrete Priming
Sealers are often applied as primers before applying other coating materials. They help seal the concrete surface, improve the bonding and adhesion of subsequently applied coatings, and prevent water ingress beneath the coatings.
Reinforcement Protection
Sealers containing migrating corrosion inhibitors can protect reinforcements like metallic mesh, rebar, and grids embedded in concrete from corrosion caused by chloride intrusion. The inhibitors leach from the sealer and migrate through the concrete to reach the reinforcements.
Curing Compounds
Some sealer formulations can be used as concrete curing compounds, retaining moisture in freshly placed concrete to achieve desired compressive strengths during curing.
Crack and Joint Sealing
High molecular weight methacrylate sealers can fill cracks and joints in concrete surfaces to depths of around 0.5 inches, depending on crack width. Sealers are also used to seal construction joints and work joints in concrete structures.
Skid Resistance
Certain sealer formulations, when combined with aggregates like silica sand, can provide skid-resistant surfaces on concrete floors, pavements, and bridge decks.
Application Cases
| Product/Project | Technical Outcomes | Application Scenarios |
|---|---|---|
| Penetrating Concrete Sealers | Penetrate deep into concrete pores, forming a chemical barrier that prevents water, chlorides, and other contaminants from entering. Enhance durability and longevity of concrete structures. | Ideal for protecting reinforced concrete structures like bridges, parking garages, and marine environments from corrosion and deterioration. |
| Acrylic Concrete Sealers | Form a protective film on the surface, enhancing resistance to abrasion, staining, and chemical attacks. Improve aesthetic appearance and ease of maintenance. | Suitable for decorative concrete surfaces, driveways, patios, and indoor flooring where a glossy or matte finish is desired. |
| Silicate Concrete Sealers | React chemically with concrete to form an insoluble gel, blocking pores and capillaries. Enhance resistance to water ingress, freeze-thaw cycles, and chemical attacks. | Recommended for horizontal concrete surfaces exposed to harsh weather conditions, such as pavements, bridge decks, and industrial floors. |
| Siloxane Concrete Sealers | Penetrate deeply into concrete, forming a water-repellent barrier while allowing breathability. Protect against moisture intrusion, chloride ion ingress, and efflorescence. | Ideal for vertical and overhead concrete surfaces like walls, ceilings, and facades, where moisture and salt protection is crucial. |
| Migrating Corrosion Inhibitor Sealers | Contain corrosion inhibitors that migrate through concrete and form a protective layer around embedded steel reinforcements, preventing corrosion caused by chlorides and carbonation. | Recommended for reinforced concrete structures in marine environments, coastal areas, and structures exposed to de-icing salts. |
Latest Innovations in Concrete Sealers
Environmentally-Friendly Concrete Sealers
- 100% Solids Sealers and Primers
- Solvent-free compositions formed from renewable materials like tree rosin esters and vegetable oils/plasticizers
- Provide strong adhesion, can be applied without solvents/water, produce no VOCs, and are ready for use after cooling
- Overcome issues with traditional solvent-based sealers that release hazardous VOCs
- Dual Nano-Engineered Waterproof Sealers
- Incorporate nanomaterials to alter surface chemistry and create rough nano/micro hierarchical structure
- Enhance hydrophobicity with water contact angles ≥120° and increase resistance to salt-scaling and UV again
- Improve durability compared to commercial siliconate/silane/siloxane sealers
Advanced Formulations and Application Methods
- Polymerizable Sealers with Latent Activators
- Compositions containing polymerizable malonates or cyanoacrylates with initiators/latent activating agents
- Quickly polymerize and integrate into construction process, improving waterproofing and substrate protection
- Pressurized Carbon Dioxide Application
- Two-part water-based acrylic sealer system applied using pressurized CO2 spray
- Avoids toxic chemicals, VOCs, and hazardous waste from solvent-based systems
- Provides UV stability, stain resistance, and longevity
Novel Sealer Compositions
- Flexible Carrier Films with Reactive Substances
- Planar flexible carrier films with water-reactive substances like silicates
- Allow moisture/rehydration access while sealing cracks and providing planar waterproofing
- Overcome limitations of rigid carriers and impermeable coatings
- Inorganic-Organic Hybrid Nanocomposites
- Sol-gel synthesized silica/polymer hybrids for surface treatment
- Combine advantages of organic and inorganic sealers
- Potential for enhanced performance and durability
The latest concrete sealer innovations focus on environmentally-friendly, high-performance formulations incorporating renewable materials, nanomaterials, and advanced polymerization systems. Novel compositions and application methods also aim to improve waterproofing, durability, and construction integration.
Technical Challenges of Concrete Sealers
| Environmentally-Friendly Concrete Sealers | Developing 100% solids sealers and primers formed from renewable materials like tree rosin esters and vegetable oils/plasticizers that provide strong adhesion, can be applied without solvents/water, produce no VOCs, and are ready for use after cooling. |
| Nano-Engineered Waterproof Sealers | Incorporating nanomaterials into sealers to alter surface chemistry and create rough nano/micro hierarchical structures, enhancing hydrophobicity with water contact angles ≥120° and increasing resistance to salt-scaling and UV aging compared to commercial siliconate/silane/siloxane sealers. |
| Polymerizable Sealers with Latent Activators | Developing sealer compositions containing polymerizable malonates or cyanoacrylates with initiators/latent activating agents that can quickly polymerize and integrate into the construction process, improving waterproofing and substrate protection. |
| Pressurized Carbon Dioxide Application | Developing a two-part water-based acrylic sealer system applied using pressurized CO2 spray for improved application and performance compared to traditional oil-based and water-based sealers. |
| Integral Sealer Admixtures | Developing admixture compositions containing sealing agents, dispersants, and accelerators for inclusion in concrete mixtures to produce concrete with integral sealing agents, improving performance characteristics like strength, durability, and resistance to chemical exposure. |
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