Spalling Repairs to Concrete Building Structures
Surface Preparation for Spalling Repairs:
How to spalling repairs to 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 reinforcements affected by rust and corrosion making spalling repairs necessary.
Clean and remove concrete, and rust from around the reo bars by wire brush, needle gun, sandblasting or water blasting. Then wash with clean water to remove any loose contaminants such as 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.
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.
Drizoro recommends on finishing of the repair that the repair is waterproofed using Drizoro Maxseal
• If the slurry primer dries up, or the previous layer is completely set, apply a new slurry coat to continue the job.
• Do not use any Maxrest or Maxrite 700 leftovers to prepare a new batch.
• Do not use mixing methods which cause violent mix and do not mix for prolonged periods. Spraying Texture Finished
• Do not use curing compounds on the repair.
• Do not exceed the thickness per layer in application.
• Do not exceed the amount of mixing water recommended.
The setting time is measured at 20 ºC, higher temperatures reduce setting time and lower temperatures delay setting time.
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.