What is the term Laitance?

Definition of laitance : an accumulation of fine particles on the surface of fresh concrete due to an upward movement of water (as when excessive mixing water is used)

What is Laitance removal?

Laitance is a weak layer of fine particles deposited on the surface of the screed as the anhydrite cures, this layer is too weak to tile onto and can also slow down drying times. Laitance should be removed by light abrasion using a suitable sanding machine.

How do you spell Laitance?

a milky deposit on the surface of new cement or concrete, usually caused by too much water.

What does Scabble mean?

Definition of scabble 1 : to work or shape roughly (as stone before leaving the quarry) 2 : to dress (as stone) in any way short of fine tooling or rubbing.

What causes Laitance in concrete?

Laitance is a weak, easily-crumbled layer on the surface of concrete, consisting of cement and fine aggregates that rise to the surface when too much water is added. Laitance may also be caused by over-trowelling, rain damage, or poor curing.

How do you remove Laitance from anhydrite screed?

Laitance should be removed by light abrasion using a suitable sanding machine i.e. a rotary floor scarifier and a 60’s grit sandpaper. Remove excess dust completely with a vacuum cleaner. Abrading the surface is best carried out 4-6 days after the application of the screed and can assist in the drying out process.

What causes Laitance?

What does Laitance look like?

Laitance always appears on every new concrete surface. It is the powdery, crumbly layer you see on the surface, which results from aggregates and cement rising atop when there is too much moisture or water added to the mix.

What is the bleeding of concrete?

BLEEDING in concrete is a phenomenon in which free water in the mix rises up to the surface and forms a paste of cement on the surface known as “laitance” . Bleeding occurs in concrete when course aggregates tends to settle down and free water rises up to the surface.

What is a air Scabbler?

Air-powered scabblers are ideal for removing spalling, loose, deteriorating, and oil-soaked concrete for new overlayments. They utilize carbide bits in multi-head configurations to hammer concrete or asphalt surfaces, removing bulk material at penetrations up to 1/4″ per pass.

Do I need to remove Laitance?

Depending on the product chosen, either surface laitance will need to be removed or a surface key will need to be created in our skin free /low laitance products. Allow 4-7 days to cure prior to removing laitance using Express Liquid Screed’s specialist laitance removal service.

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