Hi William. You can’t make the floor seamless from wall to wall if that is what you are asking. You can only fill and coat over contraction joints. This is what is referred to as the “seamless look”. The perimeter joints are expansion joints and must be honored. You don’t coat over them. In the latter half of the article we address using self-leveling joint fillers (such as SikaFlex) to fill expansion joints. This should be performed after the coating has been applied and cured. Does that answer your question?

Thanks!

I’ll investigate whether I can get hold of that here in Australia…

Hi David. Yes, a 100% epoxy or polyurea with some flexion is what should be used in the joints if you want to fill them and grind them flush for a seamless look. Our favorite to use is Xtreme-Set 100 by Legacy Industrial. It’s a fast setting 100% solids polyurea. You fill the joints with clean silica sand and then saturate them with the polyurea. You can grind 20 minutes later. We have a review of the product here.

I have an old concrete patio and car port with very ugly, cracked Contraction joints in it. It looks like it was painted some sort of red paint a long time ago, but that’s mostly worn away now. I want to spruce it up and make it look good with a flat surface I can paint over with something like rust-bullet duragrade and a grip-additive. I bought some Sikaflex SL and backer rod to try filling the joins, but after reading this article I guess that’s not the way to go…

So what I *should* be doing is filling with an epoxy product like those you mentioned, probably using silica sand as a backing? And then I’ll be able to sand or grind it level (love my angle-grinder…) and paint?

Thanks for all the great advice.

Hi Pavan. SikaFlex need to be mechanically removed from concrete. You can try a wire stripping brush if you have one. However, the best way would be the use of a crack chasing wheel attached to your grinder. Here are examples of them from Amazon.