Structural Repair Gunite PM
Cemix® Structural Repair Gunite PM is a single component polymer modified cement based machine applied mortar containing polymers, lightweight fillers and super plasticisers which when mixed with water results in a high build spray applied mortar. It is especially suitable for repair work in harsh environments.
Typical Application / Uses:
Cemix® Structural Repair Gunite PM is suited to large concrete column, structural or restoration repair work to be carried out using mechanically supplied dry spray process.
- Marine structures.
- Penstock linings.
- Dams & bridges.
- Water & sewage treatment plants.
- Large volume sprayed vertical & overhead repairs to concrete structures.
- Tunnel lining & repair work.
- Underside of beams & slabs.
- One component.
- Large volume high build applications.
- Vertical & overhead use.
- Minimal rebound.
- High bond strength.
- Shrinkage compensated.
- Low chloride ion permeability.
- Improved abrasion resistance.
- Polymer modified for increased durability.
Durability enhancer, steel protection & waterproofing:
Cemix® Structural Repair Gunite PM contains an integral crystalline concrete durability enhancer & waterproofing material, which further protects & waterproofs the mortar in-depth by making it completely impermeable to water borne aggressors such as chloride ions. This admixture permanently protects the mortar & imbedded structural steel from long-term corrosion & deterioration.
All concrete substrates are to be free from all oil, grease, loose weak and friable material, or anything that will inhibit a bond to the substrate. Mechanical methods of preparation such as scabbling, grit blasting, captive shot blasting, needle gunning or similar are ideal methods to ensure excellent mechanical adhesion. Any existing paints or coatings must be completely removed. Before application, dampen the concrete surface with water and allow excess water to drain away. When the surface is uniformly saturated with enough water, priming is not necessary.
Movement / Control Joints:
Honour any control joints in the concrete substrate – do not apply product over control joints.
Dampen the concrete substrate thoroughly avoiding excess surface moisture just prior to Gunite application. Apply product by dry spraying machine with the nozzleman controlling the water content and Gunite consistency. The ideal water cement ratio is approximately 0.35. The consistency should be a sticky mortar that does not slump off the substrate. Use dry spray equipment with hose diameter 25/40 and nozzle diameter 25/5. For vertical surfaces the build is almost unlimited depending on water content. For overhead surfaces the product should be layered no thicker than 100 - 150mm. After spraying, immediately screed and trowel finish as required.
It is very important to prevent early plastic state moisture loss prior to the product setting. Cure product thoroughly after it has set by keeping it wet & covered for at least 7 days. Avoid product freezing for at least 3 days.
Appearance – Sand/Cement grey powder.
Strength (MPa) - 20MPa @ 1 day; 60MPa @ 28 days.
Application Temp- 5ºC - 30ºC
Yield / Coverage – 25Kg bag with 2.5L of water would cover approximately 0.013m3.
Mixing ratio by weight: 1kg of product: 0.100L water.
Wet Density - 2.10 to 2.20kg/L
Working Time – 45 minutes at 20ºC
Bond Strength – > 3MPa
Thermal Coeff. Of Exp – 9.0 x 10-6 mm/mm/ ºC
Chloride Ion Permeability – < 1000 coulombs
The data shown above reflects typical results based on laboratory testing under controlled conditions. Reasonable variations may occur on site.
Substrate Temperature - +5°C min. / +30°C max.
Ambient Temperature - +5°C min. / +30°C max.
Clean all tools with water & brush immediately after use.
Can be stored in its original packaging in a dry place well sealed for a period of twelve (12) months after production. Do not store opened bags.
• Use only in potable water at the nozzle.
• Never apply to dry substrates.
• Minimum application thickness is 12mm.