removing bituminous coating

[Curtis Hight]

I have what I do believe is a bituminous coating on foundation walls. (Opinions for or against that judgment are welcome). I am looking at various methods of removal. A local hardware store suggested to me “multiple applications of…Jasco or Citri-strip” plus “scraping”. I am seeing an application for the RENOFIX RG 130 ECI-Plus. Is there a better approach?

 

[Cheese]

I’d definitely go with the Renofix. The citrus strip contains citrus oils and that could impact the ability of the foundation to support other coatings in the future. 

Besides, the diamond wheel imparts a nice finish to the block and enhances the “tooth” of the block for future coatings.

 

[Birdhunter]

Was that a coating to repel water?

 

[Cheese]

Just to be clear, I've removed coatings from concrete block (however, none of the asphaltic variety) using a 5" diamond wheel mounted on a RA grinder.

If this were my project...I'd scrape off as much of the coating as I could by hand, that's the easy part. Then I'd go back and attack the stubborn areas with the Renofix or a RA grinder.

But it really gets down to what kind of coating you're going to eventually apply to the concrete block. If the coating you're removing is  an asphaltic based coating, then you do NOT want to melt the coating as you're attempting to remove it, unless you're going to reapply another asphaltic coating over the original.

In my case, it was simply removing oil based paints and then applying a water based concrete slurry to the block as a colorant.

Remember...wire cup wheels can be your friend, if they become clogged with an asphaltic coating, they can be cleaned or thrown away. A single premium diamond disc is the same price as 7-10 premium wire wheels.

 

[mino]

Scraper for stuff that falls off. Heat gun (as in big gas-fired one) + scraper for that which sticks. That is how this stuff is placed on as well.

Then consider other options. If you try to grind it directly, without removing the thick layer, it will heat up, liquify and horribly dirty your tools while you will achieve almost nothing.

The RG series grinders have too high a speed to remove this stuff without melting it. Even a RAS would be too high speed.

Also, a speed-controlled angle grinder (as low speed as possible) with a very coarse sandpaper grinding disc is a better tool than the RG 130 for this as it will not clog inside and there is very little dust from bitumen. We used it for cleaning up metal roofing that previous owner tried to "patch" with this .. sticks to everything when hot but does not make dust.

 

[bobtskutter]

Would a high pressure water jet remove it?  It would make a huge mess though.

Bob

 

[Packard]

When I had my basement waterproofed, they applied roofing tar to the concrete.  But bituminous coating is also used for that application.

What is going on below grade?  Is the basement getting water intrusion?

I’m an alarmist by nature. Feel free to ignore this post.

 

[six-point socket II]

Try to remove as much of it as possible without solvents, heat or anything else that will affect its current consistency.

If you don’t want to scrape solely by hand, you can get a “striking scraper” that will work with any rotary hammer that has a “chisel only”-mode. Here’s one randomly chosen example of such a scraper: https://www.milwaukeetool.com/products/48-62-6046

As said before, heat and solvents melt or dissolve this stuff. So any mechanical removal creating excessive heat or using solvents will lead to a big mess. #1 goal should be to limit such methods to the bare, absolutely necessary, minimum. Oh, and definitely adhere to the advice given by Cheese about ensuring compatibility of used solvents with future/later used products/ coatings.

If you are feeling playful and already own the Renofix, you could try this disc once you got the bulk of it off:https://www.festool.com/accessory/s...scs/768023---dia-thermo-d130-premium#Overview

Once you got the stuff off, the Renofix will be the #1 choice for surface preparation for whatever comes after. So still enough use for it if you plan on buying one, even without ever using it on the bituminous coating directly.

Judging solely from the pictures, the scraper will do a good job. It seems pretty weathered and at the end of its lifecycle, that should help tons.

What is your plan once it is off? Current/ up to date 2k bituminous coating and a protective layer?

Kind regards,
Oliver

 

[Cheese]

Would a high pressure water jet remove it?  It would make a huge mess though.

Bob

This is another very viable option as 80% of the current coating appears to be poorly adhered to the block. Just remember that electric pressure washers are usually in the 2500 psi and under range while gas pressure washers are in the over 2500 psi range.

 

[six-point socket II]

While I have no doubts that a high pressure water jet will get some of this off, what I don’t really like about this solution - from personal experience with water jetting - is that it will send the bits off flying and then you will spend quite a bit of time collecting them from all over the place.

So yeah, will work - but create more work tidying up afterwards.

Might also be one of those times when you want high pressure but low/ less flow - when doing it that way.

Kind regards,
Oliver

 

[Curtis Hight]

Thank you for the wonderful suggestions! Answers to your questions:

Birdhunter: “Was that a coating to repel water?” The house belongs to a friend. We’re not sure of the purpose of the coating. It’s above grade in a location with only 15 inches of precipitation a year and no sprinklers.

Cheese, mino, six-point socket II: “scraping” Yes, a few days ago I saw the Spyder Scraper™ and I was pondering its use (connected to a reciprocating saw). Now with all your suggestions, I will start with it.

six-point socket II: “What is your plan once it is off?” Behr Concrete Paint.

 

[Curtis Hight]

Remember...wire cup wheels can be your friend, if they become clogged with an asphaltic coating, they can be cleaned or thrown away. A single premium diamond disc is the same price as 7-10 premium wire wheels.

Wire cup wheels driven by what tool?

 

[Peter Kelly]

An angle grinder, screws onto the arbor.

 

[Cheese]

Cheese, mino, six-point socket II: “scraping” Yes, a few days ago I saw the Spyder Scraper™ and I was pondering its use (connected to a reciprocating saw). Now with all your suggestions, I will start with it.

I've used the Spyder scraper...it's a bit goofy but if you can control it, it may work well as another tool for your adventure. It's very flexible and is definitely an option. Like so many of these situations it may take 1, 2, or 3 different tools to perform the task.

I mentioned the Spyder scraper is a bit goofy to use...that's because it's a 5"-6" long blade on the end of a 20" long Sawzall. It can get unwieldy, perhaps the shorter Milwaukee Hackzall would make things easier.