When considering a road construction project, large or small, you may be wondering about microsurfacing vs slurry seal. By all accounts, the two approaches seem very similar, so it helps to explore their differences and similarities and the pros and cons of each.
As micro surfacing is an offshoot, or even an improvement upon, slurry-seal, it might seem like a no-brainer to simply go with the new and improved version of road paving. But the reality is that, while slurry- seal is a much older form of applying asphalt to roads, it still holds tremendous value. The key to deciding which application will work best for your project is exploring your specific needs, your budget, and how each approach fits accordingly.
Slurry seal is a form of road paving developed in the 1930s in Germany to improve roads. Cars had already begun to take their toll on autobahns in Europe, battering the pavement with wear and tear that led to cracks and potholes that could damage vehicles and lead to severe accidents and injuries. Engineers then formulated a mixture of fine crushed aggregate (small rocks), emulsified asphalt, additives, and water to apply to damaged roads to make quick repairs and give them a longer life. That longer lifespan meant fewer large road construction projects that delayed or stopped travel and traffic altogether.
To apply a slurry seal, a truck with all the necessary materials travels down a road with an onboard mixer. As the materials are combined and mixed, the resulting slurry seal is fed onto the road from behind the truck within the box’s confines. The box evenly distributes the slurry seal, and workers stand at the back of the truck, smoothing out the application as it flows onto the road, ensuring proper spread. A piece of burlap is often also dragged behind the truck to help produce a smooth final product. The slurry seal then requires 4 to 6 hours in the hot sun to fully set into the pavement, at which point it can be driven on.
The benefits of slurry seals include cost-effectiveness and quick application. The materials are relatively cheap and easy to find, and repairs can be made on short notice. Slurry seal will then prolong the life of the road surface and set in further as time goes on. Because it is a soft, pliable product, it will continue smoothing out the road even more over the following weeks, months, and years.
The primary downside to slurry-seal is the time required to set. In emergency situations, roads with slurry-seal would not be able to be driven on without worrying about creating a mess of vehicles from the splash of slurry seal materials onto vehicles. Further, slurry seal requires hot weather to set, so you would not be able to apply it during cold weather or at night. Finally, because a slurry-seal is so soft and pliable, it can only be applied in thin layers, not in thicker or multiple layers.
Microsurfacing is an update to slurry seal. Micro-surfacing was developed in the late 1960s and early 1970s to improve slurry seal’s downsides. Still using an aggregate of small, crushed rock, emulsified asphalt, and water, microsurfacing also includes a chemical that allows this combination to be layered on more thickly and will dry much quicker. A polymer is also often added to provide better mixing.
Application Micrsurfacing uses the same technique as a slurry seal for application. What is known as a “slurry truck” will have all the necessary ingredients on board, as well as the onboard mixer, which will mix and spread the wet ingredients onto the road. In general, micro-surfacing is used in emergencies, for longer-term projects, and prevention, as opposed to repair.
A microsurfacing project can reduce life costs of road repairs by up to 45% and add 6 to 8 years or more to your road, staving off large road construction projects. Like with the slurry seal, micro-surfacing will flow from the rear of the truck, with workers holding smoothing tools to guide the material over the road as it flows, ensuring total, smooth coverage and preventing the mixture from covering concrete improvements like gutters. Micro-surfacing can be applied again and again in as many layers as demanded by the project.
The biggest benefit of micro-surfacing is that it can dry quickly and in any weather. A road that needs preventative measures before significant damage can benefit from a micro-surfacing project. This can be done in the middle of the winter or even in the middle of the night, with little to no interference to traffic or travel. Microsurfacing can also benefit larger road projects as it can be applied in multiple layers and higher degrees of thickness, so it can be used rather than having to take on expensive road repairs and reconstruction.
The only real downside to micro-surfacing is its cost, which is a bit higher than slurry seal because of the chemicals added, and those costs can add up if you apply multiple layers. Some estimates have micro- surfacing at $2.50 per foot, whereas slurry seal can be as low as $2.25 per foot.
Microsurfacing vs Slurry Seal
Ultimately, the decision of micro-surfacing vs slurry seal will come down to need and budget. In general, it is safe to say that micro-surfacing is best in cases where you have large road projects where you hope to stave off construction and would like to take a proactive, preventative approach upfront. Slurry seal is best when you have damage you want to be repaired quickly in the hopes of staving off those much more extensive projects for a while longer. Of course, if you have any questions, you can contact one of our consultants at Tuscon Asphalt, where we are happy to help you make the right road improvement project decision for you.