Light surface scaling with sound concrete below
- Likely next step
- Evaluate surface repair
- Why it matters
- A shallow defect may be suitable for localized repair or resurfacing after diagnosis.
Concrete Spalling: Causes and Repair
Concrete spalling is the breaking, flaking, or loss of surface concrete, often leaving a rough depression or exposing aggregate and reinforcement. A durable repair removes unsound concrete, addresses contributing moisture, freeze-thaw, salt, corrosion, or material problems, prepares sound edges and substrate, and replaces the lost section with a compatible repair system.
Start with the condition, not the product
Hollow-sounding or delaminated areas
- Likely next step
- Map and remove unsound concrete
- Why it matters
- The visible opening may be smaller than the detached area below the surface.
Exposed rusty reinforcement
- Likely next step
- Obtain a defined repair scope
- Why it matters
- Corrosion products expand and can continue breaking surrounding concrete.
Widespread deep deterioration
- Likely next step
- Compare repair with replacement
- Why it matters
- Many adjacent repairs can be less predictable than rebuilding a failed section.
Separate spalling from simple discoloration
Spalling involves material loss. Scaling is usually shallower surface flaking, while delamination is a separation below the surface that may sound hollow before it opens. The distinction matters because a coating cannot restore detached or unsound concrete.
- Mark loose, hollow, cracked, and previously repaired areas
- Record whether aggregate or steel is exposed
- Look for water, salts, leaking joints, and poor drainage
- Note whether the affected area grows after winter or wet periods
A proper patch reaches sound concrete
The repair boundary should extend beyond loose material. Preparation may include saw cutting, removing deteriorated concrete, cleaning and evaluating exposed reinforcement, conditioning edges, cleaning the substrate, placing compatible repair material, finishing, and curing.
- Repair dimensions and depth
- Removal and surface-preparation method
- Treatment or replacement of damaged reinforcement
- Repair material and bond requirements
- Curing, weather protection, and return-to-service time
Correct water and durability problems
ACI identifies reinforcement corrosion, freeze-thaw deterioration, and chemical attack among causes of horizontal surface deterioration. Drainage, saturation, deicing exposure, joint failure, and insufficiently durable concrete can therefore matter as much as the patch material.
- Redirect ponding and runoff
- Repair failed joints where appropriate
- Use a compatible system for the exposure
- Do not coat over active moisture or unsound concrete
Technical references and limitations
These references explain general repair principles. Residential conditions, local codes, product requirements, and structural significance vary. Use a qualified local professional for diagnosis and design where safety or structural performance is involved.