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How to Identify Spalling Concrete or Concrete Cancer in your Building and then do the Concrete Spalling Repairs

The presence of spalling concrete is usually identified by the formation of

1. Slightly Raised Cracks and divots forming in concrete

2. Large bits of concrete missing or about to fall off

3. Exposed, corroded and rusty, steel reinforcement

4. Drummy or cracked render

5. Rust coloured water stains running along cracks in concrete

6. Concrete Cancer usually showing weakened eroded concrete

7. Damaged masonry, bricks, tiles or render

8. Unsightly concrete damage

9. Failure of waterproofing membrane coating

10. Potential falling debris hazard

11. Potential structural failures

Please Watch the How to do Concrete Spalling Repairs Video

Drizoro Maxrest – structural repair of spalling concrete structures

How to Repair Spalling Concrete or Concrete Cancer in your Building

Surface Preparation of Concrete Spalling for Repair: 

The repair of concrete cancer requires that surfaces should be clean and free of dirt, grease and loose particles.
Remove all damaged and unsound concrete to expose a structurally sound substrate.

Preparation of corroded and rusty Reinforcement steel

Expose all reinforcement affected by rust and corrosion.
Clean and remove concrete, and rust from around the reo bars by wire brush, needle gun, sandblasting or water blasting and wash with clean water to remove any dust, oil and grease.

Apply Maxrest® Passive , without dilution or addition of other materials. Apply by brush, spray gun or by immersing the reo elements to be protected.
Apply two coats, the second one when the first coat is dry to touch (between 2 – 3 hours at 20ºC).
Avoid painting the surrounding concrete around the reinforcement. More successive coats can be applied if required.

Apply Maxrest or Maxrite®700 for the Structural Concrete Repairs:
For an optimum bond, prepare a slurry mixing 5 parts of Maxrest or Maxrite®700 with 1 part of water, mixing well until achieving a homogeneous consistency without any lumps.
Apply the slurry using a Maxbrush onto the concrete cancer surface to be repaired and the reinforcement bars. While the slurry is still damp start placing Maxrest or Maxrite®700 with its consistency of repair mortar to fill all voids and pores, allowing 5 to 8 minutes before continuing the repair.
Keep repair damp and apply in successive layers between 2,5 and 3 cm, scratching the surface with the trowel to make the next layer adheres firmly.
Between layers, wait 10 to 15 minutes depending on temperature.

If the different layers become warm, wet the surface with cold water.

Mixing:
A 25 kg bag of Maxrest is mixed with between 3,5 to 4,0 litres of clean water, depending on the ambient conditions and the consistency required, either manually or mechanically by low speed drill (400 – 600 r.p.m). Maxrest takes fifteen to twenty minutes to set, depending on the temperature.

Maxrite®700 is mixed exclusively with clean water, free from contaminants, either manually or mechanically by low speed drill (400 – 600 rpm). One 25 kg. bag or drum of MAXRITE 700 requires about 3,75 to 4,25 litres of water to achieve proper consistency of a repair mortar (16% ± 1%).
For applications using pump or spray the mixing water can by increased up to 4,5 litres per bag. In any case these quantities are only indicative and should be checked depending on the desired consistency and the existing ambient conditions.

Mix only the amount of Maxrest or Maxrite®700 that you can be applied within eight to ten minutes.

Drizoro recommends on finishing of the repair that the repair is waterproofed using Drizoro Maxseal  

IMPORTANT CAUTIONS when using Concrete Spalling Repair Products

• If the slurry primer dries completely, or the previous layer is completely set, apply a new slurry coat to continue the concrete spalling repair
Never use any Maxrest or Maxrite®700 leftovers to prepare a new batch.
• Do not use mixing methods which cause sheering or violent mixing and do not mix for prolonged periods. Spraying Texture Finished
curing compounds are not to be used on the repair.
Exceeding the recommended thickness per layer in application will result in cracking.
• Do not exceed the amount of mixing water that is recommended. Reduces finished strength of repair mortars.
The setting time is measured at 20 ºC, higher temperatures reduce setting time and lower temperatures delay setting time. Keep Powder in cool dry place.

Application Conditions:

Do not apply at temperatures below 5 ºC or if lower temperatures are expected during the 24 hours following the repair. Do not apply on frozen or frosted surfaces.
Curing: For better curing once the job is finished cover with wet cloth to protect from high temperature or direct hot sun.

Cleaning:

Clean all tools and equipment immediately with water after use. Once Maxrest or Maxrite®700 hardens it can only can be removed by mechanical methods.

Consumption: 

Estimated consumption of Maxrest approximately 1,67 kg/m2 per 1 mm thickness. One kilogram of Maxrest will fill approximately 0.6 litres.

Estimated consumption of MAXRITE 700 are approximately 1.85 kg/m2 per mm. thickness. One 25 kg. sack of MAXRITE 700 fills approximately 13.75 litres (0.54 l/ kg of product).