Gravel Road Maintenance

Dust Control

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When a bituminous dust control is applied to a gravel road, a thin layer of liquid asphalt is sprayed directly on the gravel surface as a bonding agent and allowed to cure for at least one day. Then a chip seal layer is applied. First, a thin layer of liquid asphalt is sprayed on the road surface followed by a machine that spreads a layer of small inch washed gravel onto the liquid asphalt. The road is then rolled with a compactor. Later, another coat of asphalt is applied over the inch chips and a second layer of smaller inch chips are applied as the final driving surface. The road is again rolled with a compactor. Traffic is allowed back on the road within an hour of the final application. After a few days the road may be swept to remove any loose chips.

 


After the road has been prepared for a dust control treatment, magnesium chloride is applied. Each year previously treated roads must be retreated with magnesium chloride and as the roads are retreated dust abatement improves. Magnesium chloride is a great intermediate solution to reducing dust on low volume roads.

 


During a dust control project all vehicles must be removed from the street so that there are no obstructions. The street is then prepared by grading and adding gravel where needed.

 


Mesa County's dust control program consists of two types of treatments. One, the application of thin layers of liquid asphalt material followed by an aggregate cover called Dust Control (Bituminous). Two, a treatment of magnesium chloride called Dust Control (Magnesium Chloride). The method using asphalt and aggregate is much more costly and is used on roads having traffic volumes exceeding 150 vehicles per day. Magnesium chloride is used on roads with lower volumes of traffic.

 


Dust control is usually done in late spring and early summer. Each year a list of roads is identified and a program is developed.

 


Both dust control methods effectively reduce dust and routine maintenance. The bituminous product is a long-term solution to controlling dust, but it is expensive and costs nearly 20 times more than magnesium chloride.