Filling cracks in concrete or between bricks...

[KFC911]

A few weeks ago I bought a tube of Dap (I think it was) out of the 3-4 different types Lowes had .... it flowed out of basement horizontal wall cracks like warm honey... no bueno. Need something more viscous that will stay put between exterior brick wall cracks. The foundation pros I had on site mentioned something else (also in a tube) but not sure what it was. I want a concrete filler that flows and stays in place like caulk... help?

[Crowbob]

How wide are the cracks?

If .5” or wider, regular mason’s mortar through what looks like a giant icing-on-the-cake applicator works.

[KFC911]

Much thinner than .5 ... a few short verticle ones are .2-.3 and then an even smaller hairline horizontal crack running down a whole exterior brick wall and then some. Thanks CB!

[908/930]

Look up Sika crack flex sealant, Polyurethane based, or the mortar fix, they have a bunch of different ones.

[KFC911]

Originally Posted by 908/930

Look up Sika crack flex sealant, Polyurethane based, or the mortar fix, they have a bunch of different ones.

Been looking ... they have a bunch, DAP and Sakrete too.... like a kid in a candy store . Methinks all the self-leveling ones are not gonna "stay put"... just like what I had before. I was filling a horizontal crack between cinder blocks in my parents' basement.... filled a few inches and then slapped some awesome waterproof tape over it before it oozed out . Messy, but effective .... it was gonna be covered by basement waterproofing material by the pros. For the outside cracks in the brick mortar, I need stuff that stays in place... Thanks!

[john70t]

Not sure how good the product is...but it really gets the material in there!

How to Repair Concrete with Epoxy Injection Techniques (NEW)

[908/930]

I think the Dap is just silicone based, try a polyurethane based one.

[rusnak]

I was going to say epoxy mortar or Patch-crete.

[fintstone]

https://retail.usa.sika.com/en/products/sealants/non-sag/sikaflexr-mortar-fix-0

[KFC911]

Thanks fint ... and everyone! That appears to be the solution even though I can't see the charts all that great on my tiny phone . I'll source a tube and I have some floor and step cracks to tackle first (test) before their brick exterior cracks. Appreciate it!

[TimT]

We have used similar products to try to seal cracks in bridge decks, bridge abutments and piers.. Timbers in old warehouses.. slabs...etc..

Its an extremely difficult process to do well and effectively.

The ports break off with seemingly the slightest disturbance.. Overpressure can blow the ports off...or blow the seal off...not enough pressure.. the epoxy doesn't migrate and fill the crack and void..

Some owners ask for core sample after the process.. I've yet to see a core where the epoxy only had minimum penetration..

Originally Posted by john70t

Not sure how good the product is...but it really gets the material in there!

How to Repair Concrete with Epoxy Injection Techniques (NEW)

[TimT]

You can make a dam or stop with some foam backer rod..

An be aware of a products suffix.... Sikaflex SL is a self leveling product..

Sikaflex LM can be used to make a dam

[HarryD]

An old crack in my garage wall started leaking water into the garage. took a diamond wheel on my grinder to widen the crack a bit and used Loctite PL Concrete Non Sag to seal. been several months and many deluges with no issues. I also like the SIKA products but could not find it at Lowes when I needed something.

[A930Rocket]

Everybody beat me to it, but epoxy sealant injected into the crack, is the way to go.

[john70t]

Originally Posted by TimT

the epoxy doesn't migrate and fill the crack and void..

Some owners ask for core sample after the process.. I've yet to see a core where the epoxy only had minimum penetration..

Good points. Different materials cited, but I'd guess a thinned mix to penetrate and lubricate followed by the thick mix would go deeper. Weather and application would be the variable.Work bottom to top as suggested in the video. The adhesion and expansion coefficients would have to match the base material of course to not create a new stress point.

[azasadny]

I used a product called "SikaFlex" in a large caulk tube and it worked great for me. I believe I bought it at Home Depot.

[zakthor]

Concrete cracks:

I don't understand the situation where you'd want something flexible. Is it because the crack is actually a moving joint?

For patching cracks from settling I've had fantastic luck using fiber reinforced ferous repair mortar. Its a blue grey color and costs ~$5/40lb bag. I chisel and roughen and clean the crack, soak the existing concrete with wet towels for a few days, then mix pretty and inject/trowel into crack. Because its mixed fairly stiff it sticks in vertical slots and dries into something like porcelain. Crazy hard and tough with a smooth almost glassy surface, it rings like metal when hit with a hammer. First time I used it I tried to break a little booger off the next day with a flathead screwdriver and ended up just wrecking the tip.

It is a demonstration that humanity finally understands the physics and chemistry of mortar. My friend works for a local concrete company and says new stuff tests at > 15000 psi.

[john70t]

Concrete is porous by nature, absorbs water and moisture, and then freeze/thaw makes it worse.

Two different applications:
Horizontal should be a "soft" mix.
Whatever is moving underneath will continue such as roots or ground heave.
Control of further water infiltration would be the main goal.
Traffic or other load is upon the concrete.

Vertical should be a "hard" mix.
Load bearing to replace the original material.
Must have enough penetration to reinforce the original material but remain soft enough to expand at the same rate.