As an industry, we always need to be focusing on how we can improve our business for the benefit of our clients, employees, and ourselves for the long term. Adapting the best practices in the industry that have been embraced by manufacturers and other business owners alike help to move our industry forward. When it comes to the installation process and the materials used for the installation process, there are a few different systems that have been embraced by some in the industry.
For example, the synthetic base using paver base panels or open graded bases have been growing in popularity in recent years. These systems help to improve our efficiency on site and help to bring our client the best possible system to meet their site needs. In reality, there is not one system that can be applied to every single application. It is best to choose the installation system that suits your site and application.
However, there is one material that should NEVER be used with hardscapes yet we still see it being stocked by suppliers and used by some contractors. Even when we search online, we see some information recommending this material to be used. This material is stone dust, limestone screenings, crusher dust, or whatever it is that you may call it. This post is dedicated to convincing you to STOP using this material for your base preparation in order to ensure that you are providing your customers with the best possible end product. If you are still using this material, now is the time to stop using it in your installs.
What is Stone Dust
Stone dust, limestone screenings, crusher dust, or whatever you may refer to it as is the byproduct of crusher run creating a dust and chip combination. Because it is basically the remains of the processing of gravel, it is typically the least expensive option of aggregate to use which is one of the advantages of using it. It is also beneficial for those that manufacture it to be able to sell it, as it is basically just the leftovers, scraps, remains of their processing. Though with many aspects of life, you get what you pay for and stone dust is not what you should be using for your hardscape installation.
Despite what will be discussed in this article, there are still many hardscape contractors that use and stand by this product in their installation. This is because for a long time this is what has been used and passed down from one contractor to the next. Though in the recent decade, using this material for your installs has come into question by governing bodies and manufacturers in the industry for good reason.
Now a common rebutle to using stone dust is, “Well I have used stone dust for years and have had no issues with it.” Just because you have not had issues that have been reported to you, does not mean that you should stick with a product that has so many proven disadvantages. Additionally, not all issues are reported by clients. If you have the referrals that allow you to cherry pick clients you likely are not choosing the clients that are picky and willing to report a small issue that arises. Also, not every project installed on stone dust is going to fail. Though it is easy to pick out those projects installed on stone dust that have failed and why.
It is time to embrace other installation methods that will allow you to improve efficiency, increase the lifetime of the project, and provide your customer with the best possible end product while making you the most money. Living in an area where we experience numerous frost cycles a year and see projects that are built improperly fail when we inevitably get those phone calls from clients wanting us to come fix their project that another contractor installed, I can almost always know what caused that issue. The use of stone dust that caused heaving, efflorescence, or polymeric sand problems is confirmed by simply lifting one stone and seeing that chip dust underneath it. It is also important to note that it does not matter the climate where you are installing it, there are still reasons why you should not use stone dust whether or not you experience frost cycles.
Why Laying Pavers on Crusher Dust is Bad
Stone dust uses do not include being used for pavers, retaining walls, or other hardscape products. There may be areas in which this material could be used, but not under any hardscape products. If you are thinking of using stone dust for a bedding layer under a patio, walkway, or driveway, here are the compelling reasons why you should not.
Does stone dust get hard? Yes, it does and this is one of the reasons people use for wanting to apply it in their installations. But this is not a good reason to use it. Stone dust does not drain well, keeping water sitting above it and below the product installed while the water very slowly if ever drains through. This causes the next two problems that are listed below, but for those that experience frost-thaw cycles will know that this water will cause a major problem. These cycles will cause shifting, heaving, and sinking of pavers.
With water not being drained properly underneath the product that is installed because of the stone dust, the bottom of pavers will slowly disintegrate over time. Unfortunately, this may not be an issue until pavers are lifted when a repair needs to be made. In this case, a major issue arises in which the same pavers will not be able to be used again. In worst case scenarios, this disintegration presents a major problem in the structural integrity of the installation. In best case scenarios, the pavers that your client wanted to reuse now need to be disposed of and new product needs to be purchased.
One of the main selling points of pavers is their durability and the fact that your client is investing in a product that is going to last them much longer than several other products on the market. But when they disintegrate from the bottom up, you are removing that selling point with the use of stone dust underneath them.
Along with the moisture problems presented above comes the issue of efflorescence. This is a salt deposit that occurs with the presence of water in concrete. With proper drainage, efflorescence should not be an ongoing concern with your install even though it may be apparent in some of the product you are installing. With a quick cleaning of the product, you can resolve this problem and it should not reoccur if installed correctly. However, if it is installed on top of stone dust then the problem will only get worse. This is because stone dust does not allow that drainage to occur, the water will sit on top of it, and the product will remain saturated creating an efflorescence problem on the surface of the stone. This is an extremely unsightly problem. It may just be a little bit, enough for your customer to brush off, but it is a problem nonetheless. One that will not go away unless the stone dust is removed.
Jointing Compounds and Sealers
Various jointing compounds on the market require there to be a moisture-free joint to be installed or at least to allow the compound to cure. This is definitely the case for polymeric sands. The joint needs to be dry for the installation and the bedding layer needs to be able to allow the water to drain after wetting to activate the sand in order for the sand to cure. With stone dust, this process cannot be achieved. Even though you may be able to achieve it because you get a dry spell in the weather and you used the perfect amount of water that it reached the bottom of the joint without over watering, water will still find its way to the bedding layer over time even with the low penetration rate of polymeric sand and will cause issues in the future. The same thing goes for sealers. When using a solvent based sealer, there cannot be any moisture present otherwise it has no way to work its way up to the surface and through the film that this sealer creates. This will only create an unsightly project.
If none of these problems that can be caused by stone dust have deterred you away from ever using the material again, then this one should. If it does not, then you cannot possibly be a client focused in your business. The use of stone dust voids the product warranty of paver manufacturers and jointing compound manufacturers. This may be worded in the warranty as being installed according to the Interlocking Concrete Pavement Institute (ICPI) standards or to the manufacturer’s standards which both include not using stone dust according to their cross-sections or installation standards. That warranty is a major selling point to your client and whether or not you discuss this with them in the selling process, they may already be aware of it through their research of the manufacturer. If a problem arises with the project and they want to reach out for a warranty claim, you will be held responsible even if you did not provide your own warranty of the project. At the very least, this will hurt your reputation as a contractor to your client and the manufacturer. If you are in business for the long term, this should definitely have you questioning if you should still be using stone dust.
Changing the material you use under your pavers may not seem like a major issue if you have not experienced problems. But this is a much larger discussion than just that. This is about your reputation and relationships that you have with your manufacturers and clients. You want to be able to provide your clients with the best possible end product that is going to last, you want that to build your reputation for the long term, and you want to create relationships with manufacturers that you can stand behind and they can stand behind your work.
Stone Dust Alternatives
The Interlocking Concrete Pavement Institute (ICPI), the governing body for best practices in the industry, does not approve of using stone dust under pavers. Their recommendation is to use a coarse-grained sand that complies with ASTM C33 standards. When comparing stone dust vs sand, this sand is definitely an acceptable material to use under pavers. It provides drainage, wont eat away at the pavers, and it compacts well. With the compaction of the pavers, the sand will work its way into the joints of the pavers from below creating that interlock that is required in an interlocking system.
This is not the only material that we recommend, as we cannot remember the last time we actually used this sand for the bedding material to seat our pavers in. These days we prefer a 3/8″ or 1/4″ clear angular chip, sometimes referred to as High Performance Bedding (HPB) for this. This allows us to work in the rain and not worry about washout, not to mention any washout that may occur over years in that project. It provides excellent drainage that prevents many of the problems discussed in this article.
This material works incredibly well in an open graded base system or as the leveling layer in a synthetic base application, both of which are systems that we have almost exclusively moved to in our business for numerous reasons. If you want to learn more about these systems and their benefits, click the links to see if they have applications in your business model.
Ultimately this article is meant to educate, not to offend. The hope is that you can approach this with an open mind and understand that you are actually doing your clients, your business, and the industry a disservice by using stone dust in your installs. Instead of sticking to what you are used to, take the time to learn new systems that will make your business more efficient. In turn this will keep more money in your pocket which will allow you to grow your business. Your reputation and relationships will grow with your clients and manufacturers. Not to mention that you can use this education as a selling point to future clients, educating them the different systems you use for the different applications and why you do so in order to bring them the most value possible.