Concrete Renovations Ltd offers an assessment survey and diagnosis of damage service.
We regularly test concrete for carbonation, corrosive contaminants and chemical reaction, as well as signs of physical and mechanical damage; this allows us to offer the appropriate solution to a given problem.
Concrete, Damage and Defects:
Mechanical
- Impact, Vibration and explosion
- Abrasion and wear
- Overloading
Chemical
- Alkali Aggregate Reaction
- Chemical Exposure
- Bacterial Action
Physical
- Thermal Movement
- Freeze Thaw Action
- Efflorescence / Leaching
- Salt Crystal Expansion
- Erosion
Concrete Damange due to reinforcement corrosion:
Carbonation
- Carbon Dioxiode (CO2) in the atmosphere reacting with Calcium Hydroxide in the concrete pore liquid
- Soluble and pH 12 - 13 : Almost insoluble and pH9
- Steel Passivated : Steel Unprotected
Stray / Electrical Current
- Metals of different electropotential are connected to each other in the concrete and corrosion occurs.
- Also corrosion can be due to stray electrical currents from transmission networks.
Corrosive Contaminants
- Chlorides accelerate the corrosion process however originally caused
- At above 0.2-0.4% they break down the passive oxide
- Chlorides can be from marine exposure or deicing salts
- Their use to accelerate concrete setting at low temperatures is now mostly banned in reinforced concrete
Freeze / Thaw Deterioration
- Critically saturated concrete occurs when over 90% of the concrete pores are full of water
- Frozen water has 9% more volume than unfrozen water. The expansion breaks off the concrete surface
