Questions on using concrete bonding agent

[MikeC55]

I may be overthinking this, but I have no experience bonding new concrete to old. I have researched the topic and think prepping the old concrete with a bonding slurry is the way to go. I plan to use Sikka Latex R bonding adhesive / fortifier and am a bit confused on the timing for pouring the concrete after adhesive application. In a product user guide, it says: Brush the mixture with a stiff bristle brush into the entire area to be resurfaced. Make sure the entire surface and all edges are covered. Apply the repair mortar immediately, before the bonding agent dries.

Then I find in a Sikka video, the comment: Extremely porous surfaces may require two coats. Allow to dry, approximately 1 hour depending on temperature and humidity, before placing repair mortars, concrete or toppings.

I am going to try contacting Sikka, but thought I would ask here too. Anyone use this product and if so, do you pour concrete while the slurry is wet or dry? I'd really like to prep things the afternoon prior to pour, since I'm renting a mixer and am not sure how long it will take to get the concrete ready.

 

[ConCretin]

My first question would be why you feel you need a bonding agent in the first place. They have their place but I can count on one hand the number of times we've used them on what must be tens of thousands of construction joints. You are generally better off with a mechanical connection using rebar or smooth dowels. Sometimes you are better off with no connection at all.

With that said, I assume the product you are using is a liquid that is mixed with cement or a powder to form a slurry? These products are generally applied just prior to concrete placement, which is true of almost all bonding agents. There are a few that allow earlier application such as Armatec 110 but I doubt it's worth the time and effort.

 

[BobnCO]

When I’ve used them they have been still wet when I poured / installed patch.

 

[zendriver]

I've used glue and not used it.

Didn't seem to make any difference if the surface was clean.

Ever spill dry cement on a dry concrete floor? Good luck scraping it off the next day. Concrete knows how to bond.

 

[Uncle murph]

I may be overthinking this, but I have no experience bonding new concrete to old. I have researched the topic and think prepping the old concrete with a bonding slurry is the way to go. I plan to use Sikka Latex R bonding adhesive / fortifier and am a bit confused on the timing for pouring the concrete after adhesive application. In a product user guide, it says: Brush the mixture with a stiff bristle brush into the entire area to be resurfaced. Make sure the entire surface and all edges are covered. Apply the repair mortar immediately, before the bonding agent dries.

Then I find in a Sikka video, the comment: Extremely porous surfaces may require two coats. Allow to dry, approximately 1 hour depending on temperature and humidity, before placing repair mortars, concrete or toppings.

I am going to try contacting Sikka, but thought I would ask here too. Anyone use this product and if so, do you pour concrete while the slurry is wet or dry? I'd really like to prep things the afternoon prior to pour, since I'm renting a mixer and am not sure how long it will take to get the concrete ready.

I have always wet down the old surface with water before repairs and it’s always bonded just fine.That’s over 45 years of experience.

 

[Leaflessshadetree]

I've used a bonding agent to repair spalling. If it stays on the surface as you brush it on then pour your concrete before it dries. If it soaks in then wait for it to dry. Apply a second coat and pour concrete before that dries.
The product I used (I don't recall exacty) was about the color/viscosity of milk. It wasn't difficult to tell when it was soaking in.

 

[PCustoms]

For what it's worth the quickcrete version says for new concrete/cement pour as soon as it dries, gypsum/finish plasters while still tacky.

I wasn't too particular when I poured my stem wall and so far so good

 

[MikeC55]

Thanks guys. I guess I'm just trying to hedge my bets, since I'm a novice at concrete and this job s way too small to call a truck. I'm basically just pouring a 3 & 1/4" curb to match the rest of the garage (changing to one larger OHD from 2 smaller ones). I'm pouring it on top of the (old) apron, which is around 8" thick and in good shape. I also chipped up the surface, to make it rough, with a mini jack-hammer. I also have 5/8" threaded anchors coming up through it for wall attachment. Good point that if the agent dries before my concrete is ready, I can always put on another coat (quickly).