Lightweight Chip Seal for Mountainous Region

by Jim Thompson, Carolina Stalite Company

This double chip seal project covered several miles in the mountainous area in Mitchell County, North Carolina. The first layer used was a 78M specification hard rock from a nearby quarry and the second layer or ride surface was lightweight aggregate (LWA). CRS-2 polymer modified emulsion was used under both layers at .27 and .25 gallons respectively. The top layer of LWA was applied at 8-9 lbs. per square yard. Both rubber tire and steel wheel rollers were used to seat the aggregates.

LWA was a good choice for this project since the roads in this area typically have a lot of curves and slope. The high friction surface of LWA provides improved skid resistance resulting in an additional level of safety. The superior particle retention characteristics of LWA essentially eliminates windshield damage. The contractor also commented that the chip spreader can more easily pull the dump truck loaded with lightweight aggregate up a grade than when loaded with hard rock. This adds another measure of safety to the paving job.

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