Dennis Wilson

Most concrete achieves a 95% cure in 28 days unless accelerators are added. The taping of plastic to the floor is for moisture content. If droplets form on the plastic, adhesives, paints and oil based sealers should not be used at that time. Most water based sealers allow vapor transmission but may also allow the migration of salts (lime, calcium, etc) to the surface of uncured floors.

Acid stains will cost about $30 per 100 square feet for a DIYer.

Dennis

Rod Underwood

Okay, Shrinkage joints are critical to the long term appearance and integrity of concrete. It is inevitable that concrete will crack, one of the purposes of the reinforcing, and NEVER pour concrete without it, is to keep the cracks that will inevitably form, tight and to control their location. a 12ft maximum dimension between joints is a good number, not a commandment. The joints need to be cut - sawn, not tooled, if they don't penetrate about 1/3 the thickness of the slab - that's 1-1/4" in a 4" slab, they are largely decorative.

Concrete is like an old girlfriend/wife, if you aren't extremely careful with it, it will make you pay. I use at least one layer of 6x6-10/10 wwm in concrete - 4inch slabs - and in vehicle bays I generally use two overlapping layers. I can also get fiber reinforced concrete for not much more that regular, so why not? Also make sure the reinforcing is pulled up into the slab and not allowed to just rest on the pea gravel. Ideally it's in the middle of the slab, but this is difficult ot control.

Reinforcing and a drainable pattern of joints are two critical issues. if they can't drain, then caulking to keep water out of joints that could freeze is important.

Concrete shrinks an amount equal to about 100 degrees of temperature differential during the curing process, so these induced tensile forces - due to shrinkage- is what creates a lot of the cracks you see in concrete. It's not always just about proper subgrade preparation, although don't discount the importance of that either. .

Rod

Normy

My new house has a garage floor that has been painted with some sort of cheap latex paint, and is in poor condition. I want to epoxy this floor, but what do I need to do first? Obviously the latex has to come off. Mechanical grinder or chemical removal?

N-

Dennis Wilson

Normy,

Try trisodium phosphate (TSP) with a buffer and green or brown scrub pads should remove the latex based paint. The TSP is available in crystals at any paint store, Lowes or Home Depot. It is also sold under the brand name of Liquid Sand. This should clean the paint off and allow the epoxy to bond with the concrete. For safety and performance sake, always follow the directions.

Dennis

dr bob

Most common latex paints come off with water and time. You can make a dike out of sand, a good hose, or whatever, and leave water on it for maybe half a day. The paint will then peel of easily with a long-handle floor scraper.

I had an epoxy garage floor installed, and it's less than ideal. 150 days from new concrete, and the paint is still softer than I think it should be. Experts later tell me that I should have used the quartz chips and the topcoat to get the extra protection I need. To their credit, the vendor sent out a whole re-coat package including paint, rollers, pads for the floor machine, masks, booties, and more. They just didn't send their contractor back to do the work. Said he was not up to their standards. Duh, I think that's what I'm talking about here...

The prep for the new concrete was a scrub with a high-pH wash to get any oil and grease out of the concrete. We had new uncontaminated concrete but they did it anyway. After that was done, they did an acid wash to remove any eflorescence, stray calcium, etc, and neutralize any of the remaining caustic from the first wash. They were then supposed to let it dry for a couple days, and they shortened this step to a couple hours. Expansion joints and surface imperfections get filled with an epoxy grout that takes a couple days to dry. They let it cure while the floor dried, and then rolled over it with the epoxy paint before it even started to set. The paint itself was supposed to cure for two days between coats, shortened to overnight. Top coat supposed to be walkable in a day, left it for a week since I could leave still thumbnail marks in it. Eventully had to get my shop equipment out of the driveway, and rolled it in. No cars on it for two weeks. Almost two years later, it still stains from car tires sitting on it. I ended up buying a gallon of acrylic floor sealer from a local janitor supply store to seal the surface to stop the staining. It added some gloss, some texture so it isn't so slippery, but needs to be removed and reapplied every few months. I might have just tried the acrylic sealer alone had I known how much fun the paint would be.

This spring I may try again with the stuff the vendor sent, plus the top coat stuff with the chips in it. I'll regrind the seams and level them correctly this time.

The prep chems, especially the caustic degreaser and the acid wash, are very tough on the driveway. If you do these steps, plan on sucking that stuff up with the plastic shop-vac rather than running it across any asphalt or risk getting it into plantings or lawn. Dennis' suggestion about using TSP as a degreaser is good, but it takes a lot more chemical and time than the degreaser used on my floor. Plus you still need to acid wash new concrete before painting no matter what to get the stray calcium off the surface.

Hoyo

Dear drbob.
I understand that with Your experience, the epoxy floor is not ideal.
It seems that Your/their contractor did not do the job right. Epoxy cures fairly fast and do get rock hard when mixed right.
I probably would insist to the vendor that they redo the floor at their expence.

Geir

Drewster67

http://www.jnkproducts.com/garage-floor-tiles.htm

Sorry if its a repost

dr bob

My insistence landed me the stuff to do it again. The vendor (out of state) can't seem to find a contractor willing to take on the whole job. Part of the issue is that the old epoxy floor will need to come up before a new one goes down, and that's where the problem really comes. We can find a paint guy willing to do the recoat, but we are arguing about whether the new pain goes on to concrete, or whether it can go over the old stuff. My argument is that if the old stuff isn't holding up now, why would it suddenly become good enough to hold up a new top coat? Nobody is willing to bid a fixed price to the vendor for the removal, and he doesn't want to sign a blank check to anybody. You can see my problem.

Dennis Wilson

Bob,

A good acrylic sealer, that shouldn't need stripped, is Top Shape made by Hillyard. If it wears (as acrylics do) a reapplication (after cleaning) is all that is required. It doesn't build up to the point of yellowing like some sealers.

Concerning your epoxy, it sound like the contractor used too little hardener. In some applications ( like warehouses) they want the floor to stay soft as yours is. To remove a soft epoxy floor, a solvent such as naphtha may be required. You may be better off returning the replacement epoxy, asking for a refund and contnue using the sealer.

Dennis