At a Glance: Key Applications
Use Megapoxy HT for: Structural bonding of new to old concrete, underwater repairs, high-strength epoxy mortars, steel dowel anchoring, and critical concrete crack repairs.
Megapoxy HT: A Technical Overview
Megapoxy HT is a premium, two-component epoxy gel adhesive engineered for the most demanding structural applications in civil engineering. As a 100% solids, solvent-free system, it cures with zero shrinkage to create a bond of immense strength and durability. Its key engineering advantage is its hydrophilic nature, allowing it to form tenacious bonds to damp, wet, and even fully submerged substrates where conventional epoxies would fail. With a compressive strength of 100 MPa—significantly stronger than most concretes—and excellent chemical resistance, Megapoxy HT is designed to create truly monolithic repairs that restore and enhance structural integrity.
Comparative Performance Overview
| Metric | Megapoxy HT | Standard Cementitious Mortar | Advantage |
|---|---|---|---|
| Compressive Strength | 100 MPa | ~40-60 MPa | Delivers strength far exceeding the parent concrete, ensuring the repair can handle extreme structural loads without failure. |
| Bonding in Damp Conditions | Hydrophilic (Designed for wet) | Requires Saturated Surface Dry (SSD) | The hydrophilic formulation actively displaces water to create a powerful chemical bond in damp or wet conditions, eliminating a common point of failure. |
| New-to-Old Concrete Bond | 36 MPa (Slant Shear) | Low (Relies on mechanical key) | Forms a powerful, continuous chemical bond that makes the repair and substrate act as a single monolithic unit, eliminating cold joints. |
| Chemical Resistance | Excellent (H₂S Resistant) | Poor (Porous) | Provides long-term durability in aggressive environments such as sewage treatment plants or industrial applications by resisting chemical attack. |
Using Megapoxy HT in a Complete System
Megapoxy HT functions as the core chemical link in a comprehensive structural repair system. Its performance is maximised when integrated with correct surface preparation protocols—such as grit blasting steel to an AS CK 9.4 Class 3 finish or mechanically abrading concrete to remove laitance. Within a system, it can be used as a high-grip primer for new concrete overlays, or combined with select aggregates to create a high-strength epoxy mortar for patching and re-profiling. This versatility allows it to chemically fuse different components (steel, old concrete, new concrete) into a single, high-performance composite structure.
How Megapoxy HT Prevents Common Failures
Common failure prevention information
Failure Mode: De-lamination of Concrete Overlays
With an exceptional new-to-old concrete bond strength of 36 MPa (Slant Shear), Megapoxy HT creates an unbreakable chemical weld between substrates. This prevents delamination caused by differential shrinkage, thermal cycling, or high stress, ensuring the overlay and original structure act as one.
Failure Mode: Bond Failure in Damp or Underwater Areas
As a hydrophilic epoxy, it is engineered to displace water from the substrate surface at a microscopic level. This allows it to achieve a tenacious bond to damp, wet, or fully submerged concrete where conventional epoxies would be compromised, guaranteeing performance in splash zones and underwater repairs.
Failure Mode: Anchor Corrosion and Pull-Out
The 100% solids, gel formulation completely encapsulates steel dowels and anchors, creating a void-free, impermeable barrier. This isolates the steel from moisture and chlorides, preventing corrosion, while its 20 MPa bond strength to steel provides pull-out resistance that exceeds engineering requirements.
Core Features & Specifications
- Hydrophilic Formulation: Engineered to bond tenaciously to damp and wet substrates, making it ideal for challenging site conditions and underwater applications.
- Exceptional Compressive Strength (100 MPa): Cures to a strength far superior to concrete, enabling the transfer of heavy structural loads and providing an incredibly robust repair.
- High Bond Strength (36 MPa Slant Shear): Creates a true chemical weld between new and old concrete, ensuring a monolithic repair that eliminates weak cold joints.
- 100% Solids, Nil VOC: A solvent-free formula ensures zero shrinkage during cure for maximum dimensional stability and is safe for use in sensitive environments.
- Excellent Chemical Resistance: Resists a wide range of chemicals, including hydrogen sulphide, making it suitable for wastewater and industrial applications.
- Versatile Gel Consistency: Easy to mix and apply by brush or roller, and can be combined with aggregates to create high-strength, trowelable epoxy mortars.
The Megapoxy HT Advantage
- Guarantee Structural Integrity: Deliver repairs that are demonstrably stronger than the original concrete, providing confidence in critical load-bearing applications.
- Eliminate Weather-Related Delays: Its ability to bond to damp substrates means work can continue in conditions that would halt projects using conventional epoxies.
- Achieve a True Monolithic Structure: Go beyond simple patching. The incredible bond strength chemically fuses repair sections to the substrate, enhancing the entire structure's performance.
- Engineer with Confidence: Backed by comprehensive ASTM testing for all key mechanical properties, providing verifiable data for engineering specifications and compliance.
Applications in Practice: Trade Scenarios
For Remedial Contractors: Underwater Pylon Repair
The Engineering Challenge: Repairing spalled concrete on a bridge pylon within the tidal splash zone. The repair material must be applied to a permanently damp surface and cure underwater while resisting erosion and chloride attack.
The System-Based Solution with Megapoxy HT: After mechanically removing unsound concrete, apply Megapoxy HT directly to the saturated substrate as a bonding primer. Its hydrophilic properties will ensure it achieves a full bond. Immediately form and apply an epoxy mortar made by mixing Megapoxy HT with specified aggregates. The system cures to form a seamless, high-strength, impermeable patch.
Best Practice Note: Surface preparation is critical. Use high-pressure water blasting or mechanical abrasion to remove all marine growth and laitance to expose a sound, aggregate-filled concrete surface.
For Commercial Builders: Anchoring Structural Steel Columns
The Engineering Challenge: Securing base plates for structural steel columns to a concrete slab, requiring a grout that provides absolute load transfer and prevents any future movement or corrosion.
The System-Based Solution with Megapoxy HT: Use Megapoxy HT to create a high-strength epoxy mortar. After positioning and levelling the column base plate, pour the mortar into the formwork. The material's high compressive strength (100 MPa) and minimal shrinkage ensure full, void-free bearing, while its bond strength to steel (20 MPa) creates a monolithic connection between the column and foundation.
Best Practice Note: Ensure steel base plates are prepared by grit blasting to a Class 3 finish and degreased immediately prior to grouting to achieve maximum tensile bond strength.
Certifications & Regulatory Compliance
Megapoxy HT is manufactured to stringent quality standards, with its mechanical properties independently verified against multiple international ASTM test methods. These include Compressive Strength (ASTM D695), Bond Strength (ASTM D4541), Tensile Strength (ASTM D638), and Flexural Strength (ASTM D790). The product is a Nil V.O.C. (Volatile Organic Compounds) formulation, contributing to higher air quality standards on site. All components are listed on the Australian Inventory of Chemical Substances (AICS).
Storage & Shelf Life Considerations
For optimal performance, store Megapoxy HT kits in a cool, dry, well-ventilated area, protected from direct sunlight. Keep containers sealed when not in use. Proper storage is essential to maintain the product's workability and ensure it meets its specified cured properties. Avoid exposure to extreme temperatures.
Frequently Asked Questions About Megapoxy HT
Q: What does "hydrophilic" actually mean for a job site application?
A: It means Megapoxy HT is chemically designed to bond successfully to damp or wet concrete. Unlike standard epoxies that can fail if moisture is present, its formulation actively displaces water from the surface to create a direct, powerful chemical bond. This is critical for any external, below-ground, or underwater repair.
Q: How critical is the 3:1 mix ratio? What happens if I'm slightly off?
A: The 3 parts A to 1 part B mix ratio by volume is essential and must be accurate. Inaccuracies will compromise the final cure and all specified mechanical properties like compressive strength. Significant errors can result in a system that fails to cure correctly, remaining soft or sticky and requiring complete removal.
Q: The cure time varies with temperature. How do I plan my work in winter vs. summer?
A: At 35°C, you have a 12-hour cure; at 15°C, it's 48 hours. The work time is 30 minutes at 25°C and will be shorter in summer and longer in winter. In hot weather, only mix what you can apply in 15-20 minutes. In colder weather (min 10°C), you'll have more working time but must factor in the longer cure before applying loads.
Q: Can I use this to repair a hairline crack in a slab?
A: While it has immense strength, Megapoxy HT is a gel adhesive. For very fine, non-structural hairline cracks, a lower viscosity liquid epoxy would be better suited for gravity-fed penetration. Megapoxy HT is ideal when the crack is wide enough to be filled or when it's chased out and repaired as part of a structural fix.
Applications & Benefits
| Application / Use Case | Key Benefit | Primary Trades |
|---|---|---|
| New to Old Concrete Bonding | Creates a 36 MPa slant shear bond, making the repair stronger than the concrete itself. | Remedial Contractors, Builders |
| Steel Anchoring / Dowelling | Achieves 20 MPa tensile bond to steel, providing exceptional pull-out strength. | Builders, Steel Fixers, Civil Contractors |
| Structural Concrete Repairs | 100 MPa compressive strength restores structural integrity to damaged elements. | Civil Contractors, Remedial Contractors |
| Underwater and Splash Zone Repairs | Hydrophilic nature allows for tenacious bonding to wet and submerged substrates. | Marine Contractors, Remedial Contractors |
| High Strength Epoxy Mortars | Can be mixed with aggregates to create a high-performance, trowelable repair mortar. | Flooring Contractors, Builders |
Applying Megapoxy HT: Protocols & Best Practices
General Application Steps:- Preparation: Ensure the substrate is prepared to the required standard as per the Adhesion & Preparation Guide.
- Mixing: Accurately measure 3 parts of Part A to 1 part of Part B by volume. Mix thoroughly with a slow-speed drill and paddle mixer until a completely uniform, streak-free grey colour is achieved. Inaccurate mixing will result in poor performance.
- Application: Apply the mixed gel using a brush, roller, or trowel. When used as a bonding adhesive for new concrete, apply at 1 to 1.5 litres per square metre and place the new concrete within 15 minutes.
- Curing: Protect the applied product from contaminants while curing. Allow for the minimum cure time based on the ambient temperature (e.g., 24 hours at 25°C) before subjecting the area to service or load.
For Remedial Contractors: Underwater Pylon Repair
The Engineering Challenge: Repairing spalled concrete on a bridge pylon within the tidal splash zone. The repair material must be applied to a permanently damp surface and cure underwater while resisting erosion and chloride attack.
The System-Based Solution with Megapoxy HT: After mechanically removing unsound concrete, apply Megapoxy HT directly to the saturated substrate as a bonding primer. Its hydrophilic properties will ensure it achieves a full bond. Immediately form and apply an epoxy mortar made by mixing Megapoxy HT with specified aggregates. The system cures to form a seamless, high-strength, impermeable patch.
Best Practice Note: Surface preparation is critical. Use high-pressure water blasting or mechanical abrasion to remove all marine growth and laitance to expose a sound, aggregate-filled concrete surface.
For Commercial Builders: Anchoring Structural Steel Columns
The Engineering Challenge: Securing base plates for structural steel columns to a concrete slab, requiring a grout that provides absolute load transfer and prevents any future movement or corrosion.
The System-Based Solution with Megapoxy HT: Use Megapoxy HT to create a high-strength epoxy mortar. After positioning and levelling the column base plate, pour the mortar into the formwork. The material's high compressive strength (100 MPa) and minimal shrinkage ensure full, void-free bearing, while its bond strength to steel (20 MPa) creates a monolithic connection between the column and foundation.
Best Practice Note: Ensure steel base plates are prepared by grit blasting to a Class 3 finish and degreased immediately prior to grouting to achieve maximum tensile bond strength.
Limitations & Safety
Product limitations and safety information
Limitations:
- Minimum application temperature is 10°C; do not apply if the substrate or ambient temperature is below this.
- The 3:1 mix ratio is critical and must be followed precisely for the product to achieve its specified properties.
- Working time is approximately 30 minutes at 25°C. This time will be shorter at higher temperatures. Only mix quantities that can be used within this window.
Safety & Handling:
- PPE: Wear protective clothing, nitrile rubber gloves, and safety glasses/face protection at all times.
- Ventilation: Use in a well-ventilated area. Natural ventilation is typically adequate for normal use.
- Handling: Avoid all skin and eye contact. Part B is corrosive and can cause burns. Part A is a skin sensitiser. If contact occurs, wash skin immediately and flush eyes with copious amounts of water.
- First Aid: Ensure eyewash stations are accessible. If swallowed, do NOT induce vomiting and seek immediate medical attention. Refer to the SDS for detailed first aid measures.
Megapoxy HT Adhesion & Preparation Guide
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Substrate preparation guidelines
- Concrete: Surfaces must be free of grease, oil, and laitance. Clean with a heavy-duty degreaser if necessary. The best preparation is mechanical abrasion via scabbling, grinding, or grit blasting to expose the aggregate. If not possible, acid etch with a 1:1 hydrochloric acid/water solution, scrub thoroughly, and allow to dry.
- Steel: For maximum adhesion, grit blast to AS CK 9.4-1964 Class 3 finish. If blasting is not feasible, mechanically abrade the surface to a bright, clean metal finish. Immediately after abrasion, degrease the surface by flooding with an industrial-grade solvent or degreaser.
- Coated Surfaces: All existing coatings (paint, sealers, galvanizing) must be completely removed prior to application. Bonding to a coating will only be as strong as the coating's bond to the substrate. Use paint strippers or mechanical means to get back to the bare concrete or metal before proceeding with preparation.
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