How to Select & Use a Landscape Adhesive for Concrete Paving Stones or Retaining Walls

This article explores different types of adhesives for paving stone or retaining wall projects. Read this before starting on your project so you’ll know exactly which kind to use.

Surebond Rapid Set (SB-15)

One of the more common types of adhesives when it comes to concrete projects is caulk style. Western Interlock sells a couple of them, and others we don’t sell but are readily available. 

The first one worth noting is Surebond 15. It’s basically a general strength but rapid-setting adhesive. If you’re building a wall that requires lots of stacking and you don’t want things to move and shift any while you’re assembling it, this is a better glue for you because it has that rapid setup time—it gets firmer quicker.

It can be applied to wet or frozen block, like some other concrete adhesives, and has very good strength and longevity when it comes to holding step treads or capstones on your project. 

Surebond Flex-Bond Adhesive (SB-20)

The second one is Surebond 20. This is the one we sell the most of because it’s a flexible adhesive. If you’re in an area with freeze/thaw, and you have some expansion with that moisture that can get trapped in between your paving stones or capstones, this flexible adhesive will move with it and not become separated. Therefore, it gives you  a little more length, longevity, and performance. It still works on wet or frozen block, but it does have a bit more setup time than SB-15. It works really well, but it can take a bit longer to firm up. So if you’re stacking a tall wall with lots of smaller blocks, it may take a little longer for you to keep things straight and from sliding.

Loctite PL

The third option, Loctite’s PL Premium, is probably the most readily available across the US. This is a general adhesive in the construction world, and a lot of hardscape people like to use it for concrete products, whether it’s step treads, paving stones, or retaining walls. It works extremely well. It’s got really good strength, but it has no flexibility and probably the longest setup time out of these three adhesives. That said, if it’s the only adhesive you can locate near you, it is a great performing one. But again, that longer setup time and no flexibility may be an issue where you live. If it is, you can look into the SB-20 for that flexibility. Or, if you want something quick, you can get the SB-15 for your rapid set.

Applying Your Chosen Caulk

Regardless of which one you choose, the orientation of how you apply that glue is probably the most important thing to know, not only for the performance of the glue itself, but for the performance of your retaining wall or paving stones. The reason why is that if you do beads of these glues in a parallel fashion across the top of your wall, you can actually trap moisture in there, making freeze/thaw popping caps and separating walls. It will also trap lime in your block and make lime run off the face or wherever it can find an artery to run out, and that doesn’t look aesthetically pleasing. 

So when you’re using these three types of caulks, make sure you do dime-sized dollops, alternating throughout your blocks, or perpendicular lines far away from the edge of the block, to keep it from going out to the front.

SuperWet Adhesive

One niche type of adhesive in the hardscape world is Pave Tech’s SuperWet. So for us here at WI living in the Willamette Valley, the contractors we serve do a lot of projects in the wintertime when everything is sopping wet, and this specific adhesive actually only really works when the product itself is wet. So if you’re doing wall caps, step stones, or something along those lines and your materials are soaking wet, you’ll want to use this product. It’s semi-flexible. It is also partially expanding. 

The orientation is a little bit different for this glue. Instead of doing perpendicular lines or dime-sized dollops, you’re going to do an S shape with it and cover the block side-to- side with that, and you’ll get great performance out of it when it’s sopping wet.

SRW SF-8 Spray Foam Adhesive 

A newer style of adhesive in the hardscape market is a spray foam type. We’re highlighting SRW Products’ SF-8, which is semi-new. The cool thing about a spray foam adhesive versus a caulk style is that you get an absurd amount more per can of lineal feet of coverage than you would from a caulk tube. So with these larger cans, it means less time changing your caulk tubes and more time gluing. Another thing is the incredibly fast setup time. So if you’re building a wall with smaller wall units and you need that adhesive to set up quicker so you can keep things flat and level, this will help you. It’s got an eight-minute set time versus the 15 minute wait of SP-15. It really is much faster. 

It’s also semi expanding, which helps if there’s any small gaps or voids in your wall block or caps. It fills that void, creating contact and adhering much better. It’s also semi-flexible, so you still get performance in those freeze/thaw climates, and it’s also a very fast and easy to use glue. You want to make sure when you’re using this glue that you do dime-sized dollops or perpendicular lines, just like you would with those caulk styles, and keep it from coming out the face of your block.

When you have an upcoming hardscape project and you’re perusing through your hardware store looking for the right type of adhesive, try not to reach for tub and tile caulks, or general construction adhesives, because they may not be built for the weather or the purpose of utilizing concrete products and bonding them together. If you want to learn about more products you can use in your backyard, side yard, or front yard, look around our website some more or try watching practical and inspiring videos on our Western Interlock YouTube channel.