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Mountain Grout Ultra is a higher-elongation, hydrophobic polyurethane injection grout for stopping water leaks through cracks and joints where movement may occur. On contact with water, the injected resin expands into a flexible closed-cell foam that maintains its form through wet/dry cycles.
Where it works best
Choose Ultra for leaking concrete cracks and joints in dams, tunnels, underground vaults and other water-related structures where a more movement-tolerant hydrophobic seal is needed. Its 300% cured elongation distinguishes it from Mountain Grout Flexible when movement accommodation is an important selection consideration.
How it works
Ultra is a moderate-viscosity polyurethane resin used with MG Accelerator B. The accelerated resin is injected into the leak path, where water initiates foam formation. It can expand up to 25 times its starting liquid volume, while accelerator dosage, water availability and temperature influence reaction speed.
Choosing the right Mountain Grout
Ultra is the movement-focused hydrophobic option in the range. Flexible is another hydrophobic grade for wet/dry leak paths, while hydrophilic Gel Foam is intended for continuously wet conditions. The most suitable system depends on water behaviour, expected movement and injection requirements.
Key considerations
- MG Accelerator B is used to control the reaction profile; published reaction times depend on test conditions.
- Water is required to initiate foam formation, even though the cured grout is hydrophobic.
- Injection and reaction settings should be selected for the job by an experienced installer.
How is Mountain Grout Ultra reaction time controlled?
Add MG Accelerator “B” before pumping. At 25°C, 1.25% gives about 50 seconds to expansion start and 5 minutes to completion; 2.5% gives about 30 seconds to start and 3 minutes to completion.
- Wet concrete cracks and joints
- Water-bearing concrete structures
- Rock and civil structures with leaking cracks or joints
Mountain Grout Ultra Physical Properties
| Property | Value |
|---|---|
| Product Type | Hydrophobic polyurethane formulation |
| Available Sizes | 4 kg, 20 kg |
| System Components | Ultra base resin with MG Accelerator "B" |
| Base Resin Viscosity | 650 cps |
| Accelerator Viscosity | 25 cps |
| Base Resin Specific Gravity | 1.07 |
| Accelerator Specific Gravity | 0.95 |
| Base Resin Colour | Pale yellow |
| Accelerator Colour | Clear |
| Base Resin Flash Point | >121°C |
| Accelerator Flash Point | 107°C |
| Cured Density | 224 kg/m³ |
| Cured Elongation | 300% |
| Cured Tensile Strength | 300 psi |
| Cured Toxicity | Non-toxic |
| Solids Content | 100% |
| VOC Content | No VOCs |
| Expansion | Up to 25 times initial volume |
| Foam Structure | Closed-cell foam when injected into wet cracks |
| ASTM D-1638 | Viscosity |
| ASTM D-1475 | Specific gravity |
| ASTM D-92 | Flash point |
| ASTM D-1622 | Cured density |
| ASTM D-638 | Elongation and tensile strength |
| Accelerator Ratio 1 | 1.25% (1/2 pint per five gallons) |
| Reaction Time At 1.25% | Expansion starts in about 50 seconds and is complete in about 5 minutes after encountering water at 25°C |
| Accelerator Ratio 2 | 2.5% (1 pint per five gallons) |
| Reaction Time At 2.5% | Expansion starts at 30 seconds and is complete at about 3 minutes after encountering water at 25°C |