Concrete Sealer Question

Reply

  #1  
Old 07-14-13, 02:20 PM
J
Member
Thread Starter
Join Date: Dec 2007
Location: Indiana
Posts: 169
Received 0 Votes on 0 Posts
Concrete Sealer Question

Concrete Sealer Question

A little over a year ago I had a new driveway installed using an aggregate surface. After having the concrete sealed, I noticed some white and light areas within a one to two week period. The contractor said to wait awhile which I did. When the areas did not improve the contractor returned and resealed the driveway. To the best of my knowledge he did all the prep work required and I think did his job okay. I do recall one of the workers seem to tell me that these light areas will always be a possibility.

In some spots the surface looks just like the original concrete without any sealer. It appears as if the concrete rejected the sealer. So, my question is why do I see these light or white areas and is that normal?

Thanks,
Jerry
7/14/13
 
Sponsored Links
  #2  
Old 07-15-13, 12:56 PM
J
Member
Join Date: Sep 2012
Location: us
Posts: 168
Received 0 Votes on 0 Posts
I'm not sure, but is there any way there was some type of grease or oil on the concrete I don't think sealers will seal over that,
 
  #3  
Old 07-15-13, 01:22 PM
J
Member
Thread Starter
Join Date: Dec 2007
Location: Indiana
Posts: 169
Received 0 Votes on 0 Posts
Hello –
There should have been no oil or grease on the spots in question. When the concrete was first poured, in order to allow curing time, no vehicle was on the driveway for at least 7 days. And the spots appeared during that curing time and later. When it was first sealed and later resealed, the contractor did what I would call a deglazing (both times) and then applied the sealer.

Jerry
 
  #4  
Old 07-16-13, 05:33 AM
J
Member
Join Date: Sep 2012
Location: us
Posts: 168
Received 0 Votes on 0 Posts
maybe it was something when the concrete was mixed, other than that I really don't know why the sealer wouldn't stick
 
  #5  
Old 07-16-13, 01:32 PM
J
Member
Thread Starter
Join Date: Dec 2007
Location: Indiana
Posts: 169
Received 0 Votes on 0 Posts
Thanks for your input. Maybe someone else can weigh in on this.

Jerry
 
  #6  
Old 07-17-13, 06:53 AM
P
Member
Join Date: Feb 2005
Location: USA
Posts: 1,396
Received 0 Votes on 0 Posts
When you view the gray spots from an angle facing the sun, are they shiny like the rest of the surface or completely dull like unsealed concrete? If shiny, they have sealer on them but it's blushed (whitened). Buy a quart of xylol at a hardware or paint store and brush a little onto a gray spot. Stand back and let it dry about 10 minutes. The sealer should be clear again like the rest. You've simply re-melted the acrylic sealer with the xylene and released the entrapped moisture which caused the blushing.
Blushing usually occurs from applying sealer too thick.
 
  #7  
Old 07-17-13, 02:02 PM
J
Member
Thread Starter
Join Date: Dec 2007
Location: Indiana
Posts: 169
Received 0 Votes on 0 Posts
Hello Pecos -

You made an interesting reply. Some spots are dull like unsealed concrete. Other spots, although not as white "appear" to have sealer on them. So, if I use your suggestion am I in trouble if I were to use Xyol for both conditions?

I have included two pictures. They aren't as vivid as you would see by eye, but perhaps you could gain something from them.

Thanks for your reply,

Jerry
 
Attached Images   
  #8  
Old 07-18-13, 12:51 PM
P
Member
Join Date: Feb 2005
Location: USA
Posts: 1,396
Received 0 Votes on 0 Posts
That looks more like dirt or mortar on top of the concrete than blushed sealer. Are you certain someone didn't drop a blob of mortar or mud on the concrete and not get it cleaned up enough? It could also be residual cement paste from when they washed the top off to expose the aggregate. If they didn't get it cleaned off thoroughly enough before sealing it would look like that too.
 
  #9  
Old 07-18-13, 03:30 PM
BridgeMan45's Avatar
Member
Join Date: Oct 2011
Location: USA
Posts: 3,196
Received 1 Vote on 1 Post
Pictures don't show any normal-sized coarse aggregate, typical for residential concrete driveways. Instead, just an accumulation of fines, probably 1/4" maximum. Either your contractor ordered a pea-gravel mix, or he poured too wet and all the rock sank to the bottom. Hopefully, you won't have any durability problems down the road.
 
  #10  
Old 07-19-13, 04:54 AM
P
Member
Join Date: Feb 2005
Location: USA
Posts: 1,396
Received 0 Votes on 0 Posts
Bridgeman,
around here (Indianapolis area) for some reason everyone uses pea gravel for their exposed agg. They claim it's easier on their bare feet. I prefer large pebbles myself, but the photo probably is pea gravel and designed that way on purpose.
Jerry, I think the best fix would be to strip the sealer on those spots, do a light muriatic acid/water etch to remove the residue, then reseal.
One other thing to consider: Do you have an irrigation system? Does the water spray on the driveway? You know how hard our water is here. If it puddles on a slab and evaporates, it leaves hard water deposits. Is that a possibility with your concrete?
 
  #11  
Old 07-19-13, 02:23 PM
J
Member
Thread Starter
Join Date: Dec 2007
Location: Indiana
Posts: 169
Received 0 Votes on 0 Posts
Again, thanks to all who replied. And I do believe pea gravel was used for the aggragate. I should have no problems with the hard water issue you mentioned.


I decided to call the original contractor and get his input. I told him two consistent comments I had received were the concrete was not cleaned properly and/or the sealer was put on too thick. Since he had resealed the driveway, he could understand the “too thick” as perhaps being the problem, although the problem was there before he resealed it. Anyway, without me telling him first, he said he would come out and use xylol and he described what it would do which agreed with your posts. I understand your suggestion to clean the surface first, but I get the feeling he has dealt with this type of thing on other driveways and using xylol appears to be his fix. However, when I see him, I will mention your suggestion and get his views on it. So, at this point I will wait for his arrival and hope he finally solves the issue.

Thanks,
Jerry
7/19/13
 
  #12  
Old 07-25-13, 08:32 AM
S
Member
Join Date: Jul 2013
Location: USA
Posts: 1
Received 0 Votes on 0 Posts
Efflorescence on Driveway

It looks to me like efflorescence (as you ruled out hard water stains/sealer blush), which is a combination of calcium, salts & lime thats inherent in the concrete. Water is always the activator whether by 'push' (ground source water evaporating thru the concrete into the atmosphere) or 'pull' (after a heavy rain, the water evaporates out of the concrete (or brick) pores and pulls some of the salts to the surface).

A combination of the above as well as your new concrete was curing at the time e.g. water was evaporating from the mixture (this can take months depending on concrete thickness, humidity etc) likely was the cause. Sometimes efflorescence will collect under the sealer and sometimes on top. Pecos is right, that any remaining sealer should be stripped then a light acid wash applied to dissolve the 'salts'--rinse thoroughly after. Efflorescence can reoccur as some are more aggressive than others.

You might not want to reseal those areas for a few months to see if this happens. Yet given the amount of aggregate and that its a driveway, I'd stay away from a topical sealant that is easily worn away. Perhaps you could use a penetrating sealer once the remainder of the current sealant is gone. Granted you wont get the nice gloss but any shine becomes a maintenance nightmare.

Mike
 
Reply
Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description: