Concrete scaling, characterized by local flaking or peeling of the concrete surface, is a common issue encountered with hardened concrete, particularly in regions prone to freeze and thaw cycles. Understanding what causes scaling and how to prevent it is crucial for maintaining durable and aesthetically pleasing concrete surfaces.
What is Concrete Scaling
Concrete scaling occurs when the surface of hardened concrete begins to flake or peel due to exposure to freezing and thawing cycles. Initially, it manifests as small patches which may later merge and extend, exposing larger areas. The severity of scaling can vary:
Light concrete scaling: Does not expose the coarse aggregate.
Moderate concrete scaling: Exposes the aggregate with a loss of up to 1/8 to 3/8 inch [3 to 10 mm] of surface mortar.
Severe concrete scaling: Involves significant loss of surface mortar, clearly exposing the aggregate.
Causes of Concrete Scaling
Several factors contribute to concrete scaling, including:
- Lack of Air Entrainment: Non-air-entrained concrete or insufficient air entrainment makes concrete susceptible to scaling.
- Use of Deicing Salts: Excessive application of calcium or sodium chloride deicing salts on inadequately prepared concrete surfaces.
- Poor Finishing Practices: Finishing operations conducted while bleed water is present on the surface can lead to a weak surface layer prone to scaling.
- Inadequate Curing: A result of weak surface skin due to damage from freezing and thawing cycles and deicing salts.
How to Prevent Concrete Scaling
To prevent scaling and ensure the longevity of concrete surfaces, concrete contractors should follow these guidelines:
- Use air-entrained concrete with the appropriate air content for the expected exposure conditions.
- Avoid using deicing salts and chemicals on newly placed concrete surfaces for at least three months. Clean sand can be used for traction instead. Notify your snow management company if you have recently installed new concrete surfaces.
- Ensure proper drainage is installed or address drainage issues to prevent water accumulation on surfaces. Poor drainage exacerbates concrete scaling.
- Allowing proper time for initial stiffening of concrete before conducting final finishing processes is key.
- Apply proper curing methods such as liquid membrane curing compound or wet burlap covering to facilitate concrete strength development to ensure effective curing.
- Apply breathable concrete sealers or water repellents to protect concrete from moisture and deicing chemicals.
Concrete scaling poses a significant threat to the integrity and appearance of concrete surfaces. However, armed with knowledge and proactive steps, you can safeguard your concrete investments. It’s crucial to work with a contractor who prioritizes prevention techniques. By doing so, you not only extend the lifespan of your concrete surfaces but also safeguard them against the damaging effects of freeze-thaw cycles.
