A finished outdoor patio and firepit hardscape project

Choosing the Right Adhesive for Your Hardscape Project

Solvent, Polyurethane, SPUR, & Collapsible Foam: What’s the Difference?

When it comes to hardscape adhesives, we all know that one size doesn’t fit all. That’s why we’re diving into the specifics of hardscape adhesives and their distinguishing chemical properties. Knowing which adhesive to use and when will help you maximize their specific and unique strengths while leading to smoother installations and fewer callbacks. Below, we’ll explain the different formulation options available today: solvent, polyurethane, SPUR, and collapsible foam technologies. We’ll also give you real-world examples by highlighting the products that use these technologies.

By the end of this article, you’ll know everything you need to know about choosing the correct adhesive formulation to get your job done right.

Superior Strength Solvent-Based™ Adhesive

Chemical Makeup of Solvent-Based Adhesives

Solvent-based adhesives cure through the evaporation of the solvents within the adhesive. What makes this type of adhesive so strong is that the solvents push away any moisture from where the adhesive is placed on the substrate, allowing it to bond to even wet surfaces.

Our Superior Strength Solvent-Based™ Adhesive has green strength within 3-4 hours of application and is fully cured in 3-7 days. However, this curing process can be hastened by flashing (more on this below). Green strength is when the pieces no longer readily move or separate. Once cured, this adhesive is so strong that the paver or substrate will fail before the adhesive!

A paver with hardscape adhesive on it.

Speed Up Curing by Flashing

When using a solvent-based adhesive, remember to flash for faster curing. Press the surfaces together firmly, then lift the top product and immediately reposition.

A demonstration of how to flash for faster curing with solvent-based adhesives

Solvent-Based Adhesive Brag Moment

We are proud to say this is where it all began for SRW Products. It’s not only our first product, but it was the very first hardscape adhesive introduced and designed for the manufactured concrete industry. It is the adhesive that came before all the rest over 35 years ago. It’s our flagship product and, to this day, remains one of our top sellers.

This adhesive is a solid workhorse that will not disappoint whether you use it indoors or outdoors. Solvent-based adhesives work with most common hardscaping, landscaping, and construction materials. In the end, you will not find a stronger bonding adhesive.

past and present tubes for SRW's solvent-based adhesive.

Vertical Instant Lock™ Adhesive – SPUR Technology

Chemical Makeup of Silane-Modified Polymers

SPUR stands for silane-modified polymers, an advanced technology for high-performance bond and sealing adhesives. It is highly flexible and viscous, with excellent grab strength and a fast moisture cure with no shrinkage.

Our Vertical Instant Lock™ Adhesive has instant grab strength on vertical applications. It’s easy to use—you just need a premium caulking gun. This adhesive gives versatility a whole new meaning, and it can be used for everything from outdoor kitchens and manufactured stone to indoor home repairs.

Silane-Modified Polymers Points of Difference

What exactly does “instant bond and fast cure” mean? This advanced-technology adhesive instantly bonds building materials in place without any slip, sag, or additional support. Our formula is 7x thicker than traditional adhesives, providing the power to hold products up to 2” thick and weighing 25 lbs. It is even repositionable for 10 minutes, making it a faster option compared to traditional mortar for fireplaces, tiling, and outdoor kitchens, to name a few. All with a full cure in 24 hours.

Silane-Modified Polymers Uses/Applications

We alluded to the versatility above, but how versatile is it? A silane-modified polymer adhesive has strong, permanent bonds with most materials, including natural and manufactured stone, concrete, masonry, brick, veneers, glass, ceramic tile, wood, and metals. This makes it the go-to for any size project, repair, or restoration, both indoor and outdoor.

Silane-Modified Polymers Brag Moment

We are proud to say our Vertical Instant Lock™ Adhesive was the very first vertical hardscape adhesive. It also has the quickest and strongest grab of any vertical adhesive on the market. No one does it better.

Rapid-Set Polyurethane™ Adhesive

Chemical Makeup of Polyurethane Adhesives

Polyurethane adhesives are made from polymers mixed with diisocyanates and are cured by chemically reacting with environmental moisture. The MDI (Methylene Diphenyl Isocyanate) technology allows for its fast setup and cure.

Polyurethane Points of Difference

Our Rapid-Set Polyurethane™ Adhesive can be used in temperatures ranging from 45º-90ºF with green strength in as little as 60 minutes. This polyurethane adhesive is ideal for applications where the environmental temperatures could reach up to 400ºF, such as firepits.

A finished outdoor patio and firepit hardscape project

Here’s where the rapid piece comes into play: it takes a mere 24 hours to cure fully. This fast-setting adhesive bonds permanently to almost any material, even non-porous substrates. Making this the perfect job site adhesive with quick turnaround projects. Case and point: your client wants the backyard hardscape oasis done for a weekend party? No problem, use Rapid-Set Polyurethane™ adhesive for those end caps and stair threads with peace of mind knowing it will be fully cured in 24 hours.

Polyurethane Adhesive Uses/Applications

Rapid-Set Polyurethane™ Adhesive is our adhesive with the widest range of substrate uses. We talked about it working even with non-porous substrates. When using materials like foam, metal, and porcelain tile, apply a light mist of water during application to speed curing. It’s great for both outdoor and indoor use. In addition to foam, metal, and porcelain, this adhesive also works on:

  • Pavers
  • Concrete
  • Pool Copings
  • Foam
  • Vinyl
  • PVC
  • Brick
  • Metals
  • Wood
  • Natural Stone
  • Non-porous Substrates
  • Most common landscaping and construction materials
  • Firepits (up to 400°F (204°C))
  • Retaining walls

Polyurethane Adhesive Brag Moment

Our Rapid-Set Polyurethane™ Adhesive has the shortest curing time and will bond to almost anything with very high strength. We’d be remiss not to talk about the strength of Rapid Set, it can get lost against its big brother Superior Strength, taking the “strongest” title, but Rapid Set gives Superior Strength a run for its money and is no weakling.

SF-8™ Adhesive – Polyurethane Spray Foam

Chemical Makeup of Polyurethane Spray Foam Adhesives

A polyurethane spray foam adhesive is made from a chemical reaction between the chemical compounds MDI and polyols. This reaction forms the primary ingredient in our adhesive. Polyurethane spray foam adhesives come out as foam and collapse into a gel.

SF-8 adhesive foam collapsed as a gel on a paver.

Polyurethane Spray Foam Points of Difference

This is a seriously strong adhesive (we’ll talk more about that below). It has a quick 24-hour cure and is tack-free in 8 minutes.

It’s a whole new way to use adhesive. The first thing to know is that it extrudes as a foam. So, the more surface area covered, the better its bond. What does this mean? With spray foam, you get 20+ traditional tubes of adhesive out of just ONE can of SF-8™. That’s equivalent to TWO football fields worth of adhesive! Let’s put it another way: There are 600 linear feet of adhesive in each can. Impressive, we know. The cost and time savings speak for themselves.

The second thing worth noting is the dispensing. Spray foam is administered with an easy-to-use application gun instead of repeatedly pulling the trigger of a caulking gun, making application quick and easy. Simply screw the can onto the dispenser gun and go. No pumping, cutting, or puncturing of cartridge nozzles. Let’s not forget to highlight the added precision the dispenser gun gives you.

Lastly, SF-8™ keeps the job site mess at a minimum. Easily clean mistakes with the companion SF-8™ Cleaner. The cleaner clears out the dispenser gun easily and effectively, while the attached spray nozzle is used for spot cleaning on job sites for quick clean-up.

Cleaner sprayed on a paver.

Helpful Hint for Spray Foam Adhesives

As we have learned the hard way, always close the valve when storing your adhesive can and gun. Otherwise, you could have a mess on your hands.

Polyurethane Spray Foam Uses/Applications

SF-8™ can be used in a wide variety of applications, including retaining blocks, pavers, concrete, natural stone, brick, porcelain, metals, PVC, wood, and drywall. It performs great in damp and cold conditions as well as hot and dry conditions. It’s your ideal adhesive for retaining walls and caps. This adhesive is so easy to use and on such a wide variety of substrates that we’ll even go as far as to say it’s great for arts and crafts like foam, wood, and glass.

If you have not tried spray foam adhesive yet, we strongly suggest doing so, and you will soon see how great of an asset it is to your hardscape projects.

Polyurethane Spray Foam Adhesive Brag Moment

We recently put this adhesive’s strength to the test. A row of sixteen Holland pavers adhered with SF-8™ withstood over 1400 lbs. of weight with only a 24-hour cure. Now that’s strong!

SF 8 adhesive strength test demo with stacked Holland pavers

Choosing the Right Adhesive for Your Job

You now know which adhesive to use when, where, why, and which adhesives work best in different situations. In addition, we hope to have brought you solutions to avoid callbacks and to overcome any challenges you may face on a job site.

We pride ourselves on being available to our dealers and contractors alike for questions or help solving problems. If you are a contractor looking to try one of these adhesives, click here for a dealer in your area, or click here to connect with your local sales rep for a demo.

If you are a dealer looking for an in-store demo or to bring some in, click here to find your local sales rep.

If you are a homeowner, click here to find a dealer in your area.

Share Post:

Picture of SRW Products

SRW Products

Filter Blogs