mortar (cement) question

[porthos]

i have some cracks in the mortar joints between the concrete blocks in my basement. i got some stuff at lowes called sikaflex. it was the most expensive that they had so i bought it. a tube used in a calking gun. any other sugestions for filling the cracks??

[NC_JEFF]

Random cracks limited to one or two bricks aren't usually a problem and any caulk/silicone filler product will fill them. It's the cracks the "stair step" from the floor toward the ceiling or vice versa that indicate foundation involvement and caulk products will do you no good.

[Evoken]

Nc Jeff is correct. Also sikaflex is what we use for control joints in both masonry and concrete at work, I am a carpenter by trade that works for a general contractor. This product is used in commercial applications, so should be good for you.
If you are having issues with "stair" or "chasing" cracks, this is what I do.
You need to chip out the old points/joints, this can be done with a masonry chisel or diamond wheel grinder. Repoint with type M mortar, difficult to work with but it is structural mud it will hopefully stop and further damage.
Now if you have water getting in, this can be the cause of your problem or a result from your problem, but you dont want it in your basement. I parge the walls with hydraulic cement. Also a very tough product to work with. Get a nice flat trowel like you would use to finish sidewalks, I use a 12" steel. The stuff is "hot" and sets up fast,fast. Wear waterproof gloves, it will give you a chemical burn. Mix small amounts wet enough to spread. Start at the bottom with your trowel and pull the cement upward. I have done this many times including in my home, it stops water problem most of the time.

[tinsnips]

Sikaflex is a good product use it at work.

[Plate plinker]

How wide are the cracks? Also, you may have a hard time finding type M at stores setup of regular people. Type S mortar is good as well.

[Jniedbalski]

Type s has more Portland cement in it and is stronger. You usally can tell the difference because type s is slicker than type n . Type s is usally used in government buildings schools and commercial buildings

[Hogtamer]

Since y'all have good masonry knowledge, do you remember a product that you mixed from dry that contained fiberglass - then you troweled it on dry stacked blocks each side. Is there such a thing today?

[bikerbeans]

HT,

Getting a bit too much rain in the SE?

BB

[samari46]

Going back quite a few years when I lived on Long Island NY. There was a product that was a mortar fortified with fiber glass fibers. Old house that basically has been neglected. All cracks were done with a hydraulic cement mixture and actually tamped in place. Then all loose cement on all the inside walls was wire brushed to get down to a good surface. Did a section at a time so I could pay more attention to it and how it was going on the walls.
Took sometime before I was done as I worked shift work and that ate into time for home repairs. Only one spot gave me trouble. Right near a casement window. Used what looked like a plaster of paris heavy duty waterproofing cement supposedly applied with a brush. I did a heavier mix and trowled it in place. And dug out the casement window and found no drains. So the water had no place to go. And that was the cause of the problem. Took out the window, and framed out a solid wall of plywood and filled the hole with concrete. Used an old sander to vibrate on the wood dam to help break up any air bubbles each time I added concrete. All mixed by hand. All interior surfaces were wire wheeled to get rid of any dirt, and down to good concrete. When we sold the house 8 years later no leaks had appeared and passed the HUD inspection.
That house taught me a lot. Had to do a new footing/foundation for a new chimney. Won't go into it but double rebar and concrete.
Frank

[10-x]

Sikaflex is, was the best sealant/ caulk you can buy.

[porthos]

the cracks are all 1/16 in or less; most are less. should i chip out mortar to make them deeper or rely on the pressure of the caucking gun to force the silaflex into the cracks?

[rancher1913]

unless the mortar is loose, dont mess with it. you can get thoroseal, it comes in powder form and you mix it to a paint consistency and apply with a masonry paint brush, it will fill all cracks and give you a semi waterproofing at the same time. applied thick enough it would work for what you want to do hogtamer, just mix it to a peanut butter consistency.

[Plate plinker]

If the existing mortar is not decaying, I would use the best masonry grout in a tube and push it into the crack with a rubberized glove on my hand.

[porthos]

good information. thanks