New slab ok as is, or should I diamond grind?

[Quijote]

It has a smooth trowel finish. It is new and has barely been walked on with nothing at all on it. Does it still need to be diamond ground?

Also, it has a vapor barrier and is above grade, so I assume I do not need a primer.

Thoughts?

 

[Quijote]

No input?

 

[mrpizza]

Most people are at work. Allow a day or two and someone knowledgeable will give you plenty of advice.

 

[Shea]

Yes, you still need to prep your slab properly even if it is new. Grinding is the preferred method. Remember that your slab needs to have cured for at least 30 days before applying a coating.

As far as primer goes, its use is to provide for better adhesion of the epoxy base coat, help to prevent pinholes and bubbles from out gassing of the slab, and to provide for a thicker dry film thickness of the base coat since it isn't partially absorbed into the concrete. Though not all DIY people use a primer and have floors that have turned out fine, it is a highly recommended step and most professionals do not apply epoxy without it.

Here is an article on the reasons for epoxy primer if you want to learn more.

 

[Quijote]

Yes, you still need to prep your slab properly even if it is new. Grinding is the preferred method. Remember that your slab needs to have cured for at least 30 days before applying a coating.

As far as primer goes, its use is to provide for better adhesion of the epoxy base coat, help to prevent pinholes and bubbles from out gassing of the slab, and to provide for a thicker dry film thickness of the base coat since it isn't partially absorbed into the concrete. Though not all DIY people use a primer and have floors that have turned out fine, it is a highly recommended step and most professionals do not apply epoxy without it.

Here is an article on the reasons for epoxy primer if you want to learn more.

Thanks. I plan on applying epoxy about 60 days after pour.

 

[dcs Inc]

Make sure you do a vapor emissions test on the concrete before starting.... not the stupid plastic test. The 30 days thing is for the concrete to gain 80% of its compressive strength and has nothing to do with moisture in the concrete. It is estimated that concrete takes 30 days per inch to hydrate. 4" thick slab = 4 months.

 

[LegacyIndustrial]

Intermittent runoff or drainage issues will fool every moisture test.
Make sure your gutter leaders stretch far from the building as a precaution.

Shea hit the money on his advice!

 

[Armorpoxy]

Our advice is....
1. The secret is in the prep.
2. Use of epoxy primer will always give a better result and a longer lasting, thicker finish.
3. Follow the manufacturer's instructions for moisture testing (we sell expensive test kits, or the plastic sheet method works well enough most times)

 

[dcs Inc]

Good advice given by everyone. the Rapid RH test kits are expensive and not needed by a single user diy. The plastic dome kits have been used for many years and are accepted by the powers that be. These can be found as cheap as $11.00 plus shipping.

 

[Edger]

Primers are great, but if it is not prepped even they will peel off. Diamond grind and test to see if water is absorbed easily. You need to wait 30 days for hydration to slow down because it produces chemicals during that time which can adversely affect the coating.

 

[dcs Inc]

Here's a good read on the subject:

http://www.elitecreteindiana.com/decorative-concrete-non-breathable-epoxy-coatings/