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Concrete Spalling Repairs - How to repair spalling concrete


How to Identify Spalling Concrete known as Concrete Cancer in your Building

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

1. Slightly Raised Cracks and divots forming in the 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

When you have identified that you have concrete spalling areas then you are ready to commence your concrete spalling repairs!

Please Watch the How to do Concrete Spalling Repairs Video

How to Repair Spalling Concrete or Concrete Cancer in Buildings

Surface Preparation 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 by brush, spray gun or by immersing the reo elements to be protected.
The application is a two coat process.  Allow the first coat is touch dry before applying the second coat (between 2 – 3 hours at 20ºC).
Avoid painting the surrounding concrete around the reinforcement. Apply successive coats as necessary.

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.

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.
Consumption figures are only indicative.  Onsite testing of consumption at the desired consistency and 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 Repair Mortars

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 best curing cover repairs with wet cloth to protect from high temperature or direct hot sun.


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.


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).



The better the protection of the reinforcing the greater the life of the concrete