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fill joints or acid etch first or doesn't matter?
- Thread starter timtaylor
- Start date
I am going to put rocksolid down tomorrow. I filled hairline cracks with epoxy patch kit tonight and planned on etching tomorrow. The rocksolid video showed to fill cracks first...then etch. Seemed backwards to me also. My question is will rocksolid stick to epoxy patch kit? Don't think I answered your question...just stirred the pot. Sorry
Edger
Well-known member
If you acid etch first you can clean the top edges of the joint to improve adhesion of the filler. If you do it after filling the joint you have a small risk of damaging the edge of the filler when rinsing.
dcs Inc
Well-known member
Most often these crack control joints/cuts did their job and the concrete has cracked at the bottom of these. Filling them with water will cause a problem when you treat them with epoxy. If you feel compelled to use acid as a cleaner, wipe it on with a rag and then use a neutralizer to deactivate it. Don't flood it with water.
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Edger
Well-known member
Concrete is not absorbent like a sponge unless it has been soaked for a very long time or the concrete is soft. The water that goes down the joints is not a problem if you clean out the joints. I liked to flood them and use the end of a wet vac to **** up any dust, water or mud. The only time they did not dry properly was when it was very cold so we had to wait another day.
dcs Inc
Well-known member
Edger, If the concrete has cracked at the bottom of the tooled or saw cut joint then thats where the water takes forever to get out of. Taking a power washer to even a hard surface finish forces it into the concrete. Once the crud is removed then it becomes a sponge, a hard one but still porous enough to soak up water. Best to do everything as dry as possible to eliminate moisture. When filling joints it should be filled to the bottom to insure it adheres well. If just applying a bridge of epoxy then it wouldn't be as critical to keep the bottom of the joint dry. You're not getting a good weld just smearing a little epoxy on top of the joint and it will crack. Of course all of this is moot if the garage is not kept at a fairly constant temp. The expansion and contraction of the concrete due to differing temps will break the bond. It's best to honor the joints/cuts if this area isn't heated. gene
Edger
Well-known member
Once again Gene, never had a real problem except when it was very cold and I water blasted many floors, not with your DIY pressure washers, but with 6,000 psi through a rotary floor cleaner using a 150HP pump! According to your theory the water should have gone straight through and come out the other side of the slab.
I think you should do a test with concrete soaked in water to see how much soaks in and how long it takes. Break open the concrete at intervals and measure how far it penetrates. I think you will be surprised to find that it penetrates very little in the couple of hours of cleaning time and dries out very quickly.
I think you should do a test with concrete soaked in water to see how much soaks in and how long it takes. Break open the concrete at intervals and measure how far it penetrates. I think you will be surprised to find that it penetrates very little in the couple of hours of cleaning time and dries out very quickly.
dcs Inc
Well-known member
Delivering water to an open concrete slab under pressure will drive moisture into it more so than just pouring out onto the floor. The more open the surface, the deeper it is driven. I guess all the manufacturers, the ASTM, the ACI are wrong. You've done it and it's OK?
Here's the deal, concrete has different porosities. Some are hard, some are soft. Do you test for vapor emissions? A calcium chloride dome kit would for sure give you a false positive with driving water into the surface and not giving it time to escape. A RH Rapid relative humidity test? Here are a couple of URLs that I show in class. These are from a company that DOES testing for ASTM compliance.
http://www.wagnermeters.com/rh3.php
http://www.wagnermeters.com/rh4.php
http://www.wagnermeters.com/rh5.php
Here is a site to check out all their videos http://www.wagnermeters.com/rhvideos.php
How long do you recommend one to wait after driving the water into the surface before coating? That could help me understand your thinking. 6, 24, 48 hours?
I'm open to learning. I do know from experience that moisture and solvent based epoxies don't mix. I have had installers get into trouble too many times power washing a slab and just waiting 24 hours to top it. Joints/cuts will take forever to dry out.
Here's the deal, concrete has different porosities. Some are hard, some are soft. Do you test for vapor emissions? A calcium chloride dome kit would for sure give you a false positive with driving water into the surface and not giving it time to escape. A RH Rapid relative humidity test? Here are a couple of URLs that I show in class. These are from a company that DOES testing for ASTM compliance.
http://www.wagnermeters.com/rh3.php
http://www.wagnermeters.com/rh4.php
http://www.wagnermeters.com/rh5.php
Here is a site to check out all their videos http://www.wagnermeters.com/rhvideos.php
How long do you recommend one to wait after driving the water into the surface before coating? That could help me understand your thinking. 6, 24, 48 hours?
I'm open to learning. I do know from experience that moisture and solvent based epoxies don't mix. I have had installers get into trouble too many times power washing a slab and just waiting 24 hours to top it. Joints/cuts will take forever to dry out.
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dcs Inc
Well-known member
Here's a couple of other articles to look up.
ASTM E1745 / E1643
ASTM 2170
ASTM 1869-11
ACI 302-04
ACI 302
ASTM E1745 / E1643
ASTM 2170
ASTM 1869-11
ACI 302-04
ACI 302
dcs Inc
Well-known member
timtayler, Sorry for the high jacking. If you are not going to completely fill the joint down to the bottom of the crack, then you should be OK. It's hard to dry out a sub base when it's flooded with water.... takes months. If on a vapor barrier it spreads on the plastic. If you are just bridging the cut/joint then you shouldn't have any problems.
Mikaman
Member
Tim,
I'm no expert on concrete porosity ... I epoxy'ed my floor this past weekend, here's what I did and it seemed to work fine: I filled the joints with screen spline before acid etching. Yes, screen spline, not backer rod -- see my other post on this. The screen spline did not seem to be affected by the acid at all, and it kept the joints from filling up with acid & rinse water. The whole floor dried quickly after triple rinsing (regular garden hose, NOT a pressure washer). I used my shop vac to **** the water out of the joints, but honestly there wasn't that much there, it would have dried on its own in a few hours (it was about 85 deg and fairly low humidity here). Next day, I put down the epoxy, and haven't seen any problems so far. I set the screen spline about 1/8 - 1/4" below the surface on the floor, so I didn't waste much epoxy (if you don't fill the joints before epoxying, I think you'll lose a fair amount of expensive product down in the joints, esp if you have an open crack at the bottom of a joint). I plan to caulk the joints in a few days to bring them up level with the floor.
I'm no expert on concrete porosity ... I epoxy'ed my floor this past weekend, here's what I did and it seemed to work fine: I filled the joints with screen spline before acid etching. Yes, screen spline, not backer rod -- see my other post on this. The screen spline did not seem to be affected by the acid at all, and it kept the joints from filling up with acid & rinse water. The whole floor dried quickly after triple rinsing (regular garden hose, NOT a pressure washer). I used my shop vac to **** the water out of the joints, but honestly there wasn't that much there, it would have dried on its own in a few hours (it was about 85 deg and fairly low humidity here). Next day, I put down the epoxy, and haven't seen any problems so far. I set the screen spline about 1/8 - 1/4" below the surface on the floor, so I didn't waste much epoxy (if you don't fill the joints before epoxying, I think you'll lose a fair amount of expensive product down in the joints, esp if you have an open crack at the bottom of a joint). I plan to caulk the joints in a few days to bring them up level with the floor.
pauls340
Well-known member
Mikaman, many of us on this website offer our $.02 and some $.04, that's what is so valuable about this site. Many contractors will use water in their prep, because they have for years, and as its been said, water and epoxy don't mix. My two year old slab has cracked in all the control joints and I don't want any moisture or vapor coming up thru it so I Seal Bond CS-5200 all the joints and left it 1/4" short. We pre-spray the joint before we apply SB...it's a moisture cure product unlike any polyurethane. Works for me. I did my driveway with SB in 10 degree airtemps this winter. ZERO shrinkage or failure.
pauls340
Well-known member
Also, make damn sure you use the "approved" joint filler after you epoxy that floor. Also, I would think no joint filler manufacturer would guarantee their product if you acid etch after application....unless you use a acid resistant product like Seal Bond MX-13.
LegacyIndustrial
ALLIANCE MEMBER
It is risky putting a 100% solids filler over a joint that may or may not be wet still.
Beyond that is the risk of a hot-spot in the joint where the acid wasn't neutralized.
If you do it, make sure you allow "weeks" prior to installing the filler and do not wash afterwards. The water will surely get below the material and can cause more than one issue.
Beyond that is the risk of a hot-spot in the joint where the acid wasn't neutralized.
If you do it, make sure you allow "weeks" prior to installing the filler and do not wash afterwards. The water will surely get below the material and can cause more than one issue.
LegacyIndustrial
ALLIANCE MEMBER
If you are grinding you can fill the day before your first coat.
The left over moisture from an acid etch can extend the wait time depending on where you live, depth of joint, humidity, etc..
The left over moisture from an acid etch can extend the wait time depending on where you live, depth of joint, humidity, etc..
Falcon67
Well-known member
X5 or 6 on drying the cracks welll if you etch and wash. I had a few shrinkage cracks and after the second etch, I ran fans on the the cracks for a couple of days, then stole the wife's hair dryer and really got after the cracks. Only when I was satisfied they were dry did I roll the floor. Must have done it right, no issues with the small cracks. I "filled" them during the rolling by squishing the edge of the roller into the cracks. Good enough for what I'm doing.