Microsurfacing is rather similar to slurry seal. The process consists of applying a mixture of asphalt, water, emulsion, aggregate, and chemical additives to an existing asphalt concrete pavement surface. A polymer is typically added to the asphalt emulsion to provide better mixture properties.
Paving contractors in Pittsburgh, PA, will tell you that the biggest difference between a slurry seal and microsurfacing is in how they harden or “break.” Slurry relies on water evaporating from the asphalt emulsion. Microsurfacing doesn’t need evaporation. The asphalt emulsion used in microsurfacing contains chemicals that allow it to break without relying on the sun or heat to cause evaporation. Microsurfacing, therefore, hardens quicker than slurry seals and can be used when weather conditions do not allow the slurry seal to be successfully placed. Shady streets or those that have lots of traffic are great candidates for microsurfacing.
When undertaken by paving contractors, these methods consume less binder and aggregate than the traditional mill-and-fill process. Therefore, waste, emissions, and greenhouse gases are reduced, as there is no need to demolish, haul, and dispose of the old pavement. And because it is not necessary to establish a nearby aggregate source or hot-mix asphalt plant, it means that dust from crushing and screening, emissions, and energy needs are greatly reduced. Roads are also drivable within a short period after these two treatments have been applied, reducing traffic delays.