Laitance

Definition

A milky deposit on the surface of new cement or concrete, usually due to water.

Purpose

Laitance indicates excess moisture in the concrete mix, which can affect the surface strength and bonding capability of the concrete. Identifying and addressing laitance is crucial for ensuring the integrity and durability of concrete structures.

Examples of Use

• Concrete floors: Laitance may appear on newly poured concrete floors, requiring removal before applying finishing materials.
• Bridge decks: On bridge decks, laitance must be removed to ensure proper bonding of overlays or sealants.
• Industrial slabs: For industrial slabs, removing laitance is necessary to achieve a durable and wear-resistant surface.

Related Terms

• Efflorescence: A similar surface phenomenon where salts leach out of masonry or concrete, leaving a white deposit.
• Concrete Curing: The process of maintaining adequate moisture, temperature, and time to allow concrete to achieve its desired properties.
• Spalling: The breaking off of a surface layer of concrete, often due to freeze-thaw cycles or corrosion of reinforcing steel.

Notes

• Laitance can be removed through methods such as scrubbing, sanding, or using chemical cleaners.
• Preventing laitance involves proper concrete mix design, avoiding excess water, and ensuring appropriate curing techniques.
• Regular inspection of concrete surfaces can help identify and address laitance early.