Glass AggregateShiny, yet bland concrete floors are not suitable for every business, which is why the trend toward decorative concrete flooring is so prominent. Decorative concrete is especially helpful for company branding purposes, or to make a bright and impactful statement in an indoor or outdoor space.
One of the main ways to achieve a colorful and dynamic polished look is by incorporating glass into concrete overlay. There are two recommended methods with which to accomplish this – either by mixing integrally or by broadcasting. And throughout both processes, it is recommended you use CTS Rapid Set’s TRU Self-Leveling overlay, glass from American Specialty Glass, integral color from Ameripolish and CS Unitec’s HIPPO Porta-Mix.
Mixing Integrally
For the first option, it is recommended you mix the overlay initially. If you are using Ameripolish’s integral color, the water and dye are mixed together before the overlay material is added. Next, screen the product with a 1/8” classifier to remove any unmixed material or clumps. Lastly, mix the glass with the overlay. This technique is ideal for a 50% load using size 0 or size 1 glass. You want to use smaller glass because then it has a better opportunity to stay close to the surface when placing it on the floor.
In terms of the finishing technique, you can generally gauge the rake depth at 3/8” depending on the load. Be sure not to use a spiked roller – it would only succeed in pushing the glass around. Rather, for mixing integrally, the preferred finishing method is with a smoothie.
Broadcasting Glass
Glass-Infused Concrete OverlayChoosing to broadcast is a much more delicate process than mixing integrally, the primary reason being that this option really depends on the set time of the overlay. If you throw the glass too early, it will all sink to the bottom, meaning it isn’t visible. Conversely, if you wait too long, the glass will sit on the surface, not penetrating, and could be pulled out of the overlay during the initial grind.
The size of the glass influences when to broadcast since the weight of the glass is relational to the size. You can use up to a size 2, but generally size 1 is best. If the glass is larger, thus heavier, then you should wait longer. Whereas, if the glass is smaller and lighter, then broadcast sooner. Again, keep in mind: this is a delicate process, so time this as accurately as possible.
When you do the initial grind, be sure to grind the surface enough to where there is not a void between the glass and the TRU – you want the two to bond or else the polish will be diminished. Also, be aware that when you broadcast, it is difficult not to have pull-out. We have used a grout coat from Husqvarna and Metzger/McGuire to fill the pit left behind when the glass is removed.
For the broadcast finishing process, here are the steps:

  1. Place the product
  2. Gauge rake to set depth
  3. Purge any air pockets with a spike roller
  4. Soon after the product begins to set, broadcast the glass

When you get to the third step, consider using a new porcupine roller on the market, one that Joe Zingale from CTS Rapid Set recommends. The spikes are stainless steel and are 1.25″ in length. The advantage to this new roller – it doesn’t leave spike marks in the TRU like plastic spike rollers do. This new metal roller has pin-like spikes, meaning they aren’t as thick.
Once the four-step process is complete, and the initial set of the overlay occurs, do not use a trowel or any other tool to press down glass that did not fully penetrate the overlay. Doing so will leave an impression, which could be difficult to get out.
Finished WOC Concrete FlooringThe Hybrid Approach
While not usually a common method, it is possible to combine the above two techniques into a hybrid approach. Meaning, you would first mix the glass integrally, and then you would broadcast after the product is placed. However, bear in mind that this is only effective with a load less than 50%.
This is really only a surface level understanding of the glass-infused concrete overlay process, and after mixing integrally or broadcasting the final step is grinding and polishing. If you would like to learn more about the next step, or how to implement the above listed techniques, then contact a Runyon Surface Prep sales rep, or for more on the products needed during this process visit the Runyon Surface Prep website. To view this post in its original article form, see the Concrete Decor website.