New Slab- Instructions to contractor

[mas8849]

Hi All,
For new concrete being covered with something like SEC sealer or equivalent, what is best practice for new concrete slabs? Typically a cure and seal product is applied after power troweling. Is that OK for a follow up application of something like SEC sealer after the concrete is completely cured? Is a mechanical or chemical etch still required for new concrete?

I'd like to provide detailed instruction to my contractor in consideration of topcoating after cure. Hopefully this is a helpful question for others encountering the same.

 

[ConCretin]

The safest method is a moist cure as it eliminates any potential incompatibility with future penetrating sealers or coatings. Anything you apply to the slab now could present a problem down the road.

 

[Shea]

If a cure and seal product is used on the slab, it will need to be mechanically removed in order to apply a coating.

 

[mas8849]

Thanks! Great feedback. We will move forward without any additional curing or sealing agents.

 

[purediesel]

Do not use a cure and seal unless your willing to take the time to remove it later. I am currently in this situation and it's a waste of time and money to put it on. Just flood the slab with water for a few days or up to a week if possible.

 

[ConCretin]

Moist curing can be done several ways. The goal is simply to prevent mix water in concrete from evaporating prematurely. Concrete gains strength through a chemical reaction between water and cement called hydration. If the water is lost, the process is halted.

Ponding or sprinkling the slab is effective but can be difficult to apply consistently. Covering the slab will prevent drying but it can discolor the slab if sporadic drying and condensation occurs. Wet burlap works but can stain the concrete. A curing blanket such as KonCure is pricey but very effective and won't discolor or stain the concrete.

Curing protection is typically left in place for seven days, which will get the concrete to about 70% of design strength. The longer the better though.

 

[ArmchairArchitect]

Cover it with simple/cheap plastic (to retain moisture) for at least 28 days if you can to achieve full strength of the concrete. You can still drive on it after about 7 days, but keep the plastic on the full 28 days if you can.

Everything you ever wanted to know about concrete: