I know, I know. I should be posting about winter interest in the garden and feeling warm and fuzzy about the holidays, but I’m still in work mode. Warm and fuzzy will have to wait. Today, I’m writing about an important task that I recently completed which focused on the hardscape instead of the landscape. Years ago, I had a limestone sidewalk installed, and while the stone is in great shape (developing a lovely patina) the joints between the stones needed some upkeep. I added Polymeric Sand to the joints- a task I find myself doing at least every other season. And while it’s not difficult, this job has many steps.
What is Polymeric Sand? Before we get into the project details, I would like to take a moment to explain what Polymeric Sand is (sometimes referred to as Polymeric Joint Sand) and why it is beneficial to hardscapes comprised of concrete pavers, cast stone, pavements, slabs, and natural stone products.
Polymeric Sand is a fine sand with additives, such as silica and polymers which form a binding agent with the introduction of water. The binding agents lock the individual sand particles together, which in turn form a solid yet flexible bond between joints of pavers or slabs.
Benefits of Polymeric Sand. First, you get improved durability. The binding agent increases the strength of the walkway or patio. The binders allow less water into the gaps and that helps keep your foundation more sturdy.
Ordinary sand can quickly wash out or splash out with heavy rains. Loose sand also sticks to shoes and bare feet which can be tracked into your house. This is reduced tremendously with Polymeric Sand.
As gardeners, we know weeds can grow anywhere. They will grow prolifically in sand, but not so much in Polymeric Sand. We do enough weeding in our beds, we don’t need to be doing it in our hardscapes.
Ants have a difficult time making homes (or cities) within the Polymeric Sand joints. Another bonus in my opinion since ant colonies can loosen and shift regular sand with little effort.
Project Description: Readjust stones as needed and refresh joints with new Polymeric Sand.
This front walkway is made of Indiana Limestone. Over the past few years, the elements have shifted a few of the stones pieces and some the joints needed refilled. I decided to remove all the old stuff and add new. Some of the joints were ok while others were in desperate need refilling. Above: Over time, movement has occurred which is reflected in the uneven spacing between the joints. The gentle arc on the outside edge is now an eye sore due to the shifting.
I carefully loosened and pushed out the older material with a screwdriver- being careful not to scratch the stone surface. To my surprise, much of the old Poly was still holding together well. You can see the binding agents still at work in the pieces I lifted out. Above: Notice the grass beginning to grow in the joint (upper right) where the old Poly Sand has eroded. Over time the joint has collect soil and debris making it possible for weeds and grass to germinate.
I ran a shop vac over all the joints to get as much loose sand and debris out of the joints.
Next I carefully lifted and repositioned a few of the stones which had moved out of alignment. This takes time and patience! Large stones require many subtle adjustments to keep them level with the other pieces.
With the stones repositioned and the joints empty, it’s time to add the new Poly Sand. Simply open the bag and spread the sand evenly over the surface. Use a push broom to sweep it in until it’s at the proper depth below the top surface. The depth will vary according the brand of sand you use. It will expand (rise up) when it comes in contact with the water.
Remove as much of the extra product from the surface once the joints are adequately filled. I used a broom and gently blew off excess with a hand held leaf blower.
Next, use a spray nozzle attached to a garden hose on the “shower” setting to begin adding water. Take care to not wash out any sand. Let the water gently soak into the joints. Follow the rate and rest period for water application as noted on the product’s instructions. This is not the time to grab a beer or chat with the neighbor. Stay on task so the product sets up properly.
Last, sweep and or blow any excess water and sand off the surface to avoid any adherence or discoloration to the stones or pavers.
And that’s that. Whether you have concrete pavers, retaining walls or natural stone they will all require some maintenance in order to keep them looking their best. Polymeric Sand installation to fill joints and restabalize your pavers is an easy DIY project. Always read and follow the instructions on the package of the product you use.
Final notes. Don’t rush any of the steps. If you’re adding Polymeric Sand to a new project, you’ll most likely need a heavy duty tamper to settle it into the joints. This is not as necessary for reapplying to an existing area. Polymeric Sand is available in different colors.
I used PolySweep by SEK and purchased it at an architectural and landscape stone center. There are many brands available, but like anything, you get what you pay for. For best results, try to get a professional grade product from a specialty outlet.
