Concrete, brick, stone, tarmac, and slate are widely used construction materials in modern infrastructure. While durable, these materials are susceptible to environmental wear, moisture penetration, chemical exposure, and corrosion over time. To enhance their performance and extend their service life, various surface treatment systems are employed.
These treatments are applied to both horizontal surfaces like roofs and vertical surfaces such as walls. They not only protect structural integrity but also improve aesthetics and functional performance.
General Application Requirements
The effectiveness of any surface treatment depends heavily on proper application conditions:
- The substrate must be clean, dry, and sound .
- Application should occur under moderate temperature and humidity .
- A well-ventilated environment is essential for safe and effective curing.
- For liquid-applied membranes , a relatively smooth surface is required.
- All concrete repairs must be completed and fully cured before applying surface treatments—typically requiring around 28 days , though this may vary depending on the repair material.
- Proper attention must be given to detailing features such as:
- Expansion and control joints
- Window and door openings
- Drains and curbs
Purpose of Surface Treatment
The primary goals of applying surface treatments include:
- Enhancing aesthetics : Improving visual appeal through color or finish.
- Repairing minor damage : Sealing cracks and filling voids.
- Protecting against environmental elements : Preventing water ingress, chloride attack, and UV degradation.
- Extending service life : By reducing deterioration and corrosion.
- Controlling moisture levels : Crucial in preventing internal corrosion of steel reinforcements in concrete structures.
Types of Surface Treatment Systems
1. Penetrating Sealers
Description
Penetrating sealers are absorbed into the concrete matrix, where they chemically react or form a barrier within the pores. Their effectiveness is determined by molecular size and pore structure.
They do not bridge cracks , but some offer hydrophobic properties that reduce moisture intrusion into narrow cracks.
Functions
- Act as water repellents
- Serve as surface hardeners with good resistance to UV light, abrasion, and wear
Common Types
- Boiled linseed oil
- Silanes and siloxanes
- Certain epoxies
- Magnesium and zinc fluorosilicates
- High molecular-weight methacrylates (HMWM)
Solvent-based products may pose environmental concerns, while water-based alternatives are more eco-friendly.
Application Tools
- Roller
- Squeegee
- Spray
2. Surface-Applied Corrosion Inhibitors
These are specialized treatments designed to slow down the rate of corrosion in reinforced concrete structures. Their performance depends on:
- Concrete permeability
- Environmental exposure
- Type of inhibitor used
Application is often illustrated using diagrams or field examples to guide best practices.
3. Surface Sealers
Description
Surface sealers adhere to the top layer of concrete and form a thin protective film (0.03–0.25 mm thick). They can be pigmented or transparent and are available in glossy or matte finishes.
Functions
- Reduce infiltration of water, chlorides, and mild chemicals
- May decrease skid resistance
- Vary in their ability to allow water vapor transmission
Common Types
- Epoxies
- Polyurethanes
- HMWM
- Siloxanes and silanes
- Moisture-cured urethanes
- Acrylic resins
- Oil- or latex-based paints (when applied thinly)
Some products may emit volatile organic compounds (VOCs), so ventilation and safety precautions are crucial during application.
Application Tools
- Brush
- Roller
- Sponge
- Spray
4. High-Build Coatings
Description
High-build coatings are thicker than standard sealers (0.25–0.75 mm) and provide enhanced protection. These coatings are especially useful in environments exposed to UV radiation, abrasion, and mild chemicals.
They are breathable, making them ideal for exterior applications like walls and slabs-on-ground.
Functions
- Provide decorative and protective barrier systems
- Improve abrasion and skid resistance
- Help reduce reinforcement corrosion
- Resist rain, salts, and mild chemicals
- May alter appearance significantly; often pigmented
However, some high-build coatings become slippery when wet, which can limit their use in high-traffic areas.
Common Types
- Epoxy resins (often mixed with fine aggregates)
- Acrylics, alkyds, styrene-butadiene copolymers
- Vinyl esters, chlorinated rubbers, urethanes
- Silicones, polyesters, polyurethanes, polyurea
Application Tools
- Brush
- Roller
- Sponge
- Spray
5. Membranes
Description
Membranes are applied in thicknesses ranging from 0.7 to 6 mm , significantly altering the surface’s appearance. They can be bonded, partially bonded, or unbonded to the substrate.
Cracks wider than 0.25–0.375 mm must be repaired before membrane application.
Functions
- Serve as a protective layer
- Bridge narrow, nonmoving cracks
- Provide waterproofing and damp-proofing
- Function as a wearing course for traffic areas
Composition
- Urethanes, acrylics, epoxies
- Neoprene, cement, polymer concrete
- Asphaltic products
- Rigid urethane or epoxy-mortar top coats for improved durability in trafficked zones
Testing Requirements
To ensure quality, standardized tests must assess:
- Permeability
- Elongation
- Tensile strength
- Tear strength
- Adhesion
- Modulus of elasticity
- Abrasion resistance
- Low-temperature flexibility
- Water vapor transmission
Application Tools
- Brush
- Sponge
- Roller
- Trowel
- Spray
6. Overlays
Description
Overlays are 6 mm or thicker layers applied directly onto existing surfaces. Like membranes, they can be bonded, partially bonded, or unbonded.
Materials Used
- Portland cement concrete
- Latex-modified concrete
- Polymer concrete
- Silica-fume concrete
These materials offer enhanced durability, chemical resistance, and compressive strength.
Placement Methods
Installation methods depend on project requirements and are typically detailed in technical specifications or earlier design phases.
Conclusion
Surface treatment systems play a vital role in preserving and enhancing the performance of concrete and masonry structures. From penetrating sealers to robust overlays, each system offers unique benefits tailored to specific environmental and structural needs.
Proper selection, preparation, and application of these treatments are essential to achieving long-term protection, aesthetic improvement, and cost-effective maintenance. Understanding the function, composition, and limitations of each system ensures informed decision-making for engineers, contractors, and building owners alike.