One of the key benefits of opting for a liquid screed floor is its smooth, even finish, but ask any professional floor screeding contractor, and they will tell you that laitance removal is an essential step in the floor screeding process. Unlike concrete screed, laitance does not adhere well to flooring; over time, it will come loose, and your floors will no longer be level.
Failure to properly remove laitance from screed flooring will prove to be a expensive and time-consuming mistake, and will very likely set your project back weeks. Read more about why laitance removal is vital to finding perfect results with your concrete screed floor.
What is Laitance?
Laitance is an unavoidable consequence of pouring concrete. After liquid screed has been poured, fine particles like dust and debris rise to the surface and form a weak, friable skin on the concrete screed. It is usually a result of excess water in the liquid screed, too much foot traffic, or improper curing. While it may sound harmless, if the laitance is not removed it can cause a number of costly problems further down the line.
Laitance can be just a couple of millimetres thick, and you may not even notice it just by looking. As a result, it may be tempting to skip laitance removal in order to get the job done quicker, but doing so will mean that your floorings won’t adhere to the concrete screed floor underneath. That all-important smooth, even finish concrete screed is famed for will be compromised.
If you want to see laitance for yourself, simply scrape the surface with a screwdriver; any loose powder is laitance, and must be removed before work continues.
If your floor screeding contractors recommend mechanical planing, a machine fitted with rotating cutters will chip away at the concrete screed’s weak surface very quickly and efficiently. This is a great option for thicker layers of laitance.
If you’re working with a wider area of laitance, then shot blasting will provide an efficient, speedy way of cleaning up your concrete screed floor. It’s a dry process, which makes it ideal if further floor laying is going on nearby.
Scrabbling, Grinding, and Abrading
If certain areas require greater precision and control, then there are machines that allow for handheld laitance removal.
When Should Laitance be Removed?
Laitance should always be removed by knowledgeable floor screeding contractors, who will be able to determine the depth of the laitance, and assess the best method for removing it quickly and efficiently. After your liquid screed floor has been put down, they need to remove your laitance within seven to ten days.
Remember: despite its strength and durability, your liquid screed flooring can be ruined by unremoved laitance. The risks of leaving unspotted laitance on the surface of your concrete screed floor far outweigh the short-term benefits of leaving it and staying ahead of schedule. Liquid screed is an excellent material for a smooth, even finish, but it must be treated properly in order to preserve its longevity and efficacy.