1922
5650.012
Not Given
Better Roads
Article
W.O. Dannhausen
1993
December, Vol. 63, No. 12
26
N
A ceramic aggregate currently being tested on a Wyoming Transportation Department chip seal project on U.S. 85 south of Cheyenne is expected to provide increased durability while reducing windshield damage in the work zone. The lightweight Realite aggregate has previously been used successfully in chip seal projects in Colorado, prompting Wyoming officials to test the substance.Previously, a large, heavy rock chip was used in chip seal. Problems with the previous aggregate included frequent damage to windshields of vehicles in the construction zone. Additionally, this type of aggregate tends to polish from normal traffic use and snowplowing, resulting in susceptibility to skidding.
The lightweight Realite aggregate, manufactured by Wester Aggregates, weight 40 to 45 lbs/cu ft compared to the 100-lbs weight of previously used aggregate. The reduced weight results in nearly twice the volume of the substance hauled per ton, cutting transportation costs. In addition, the lighter ceramic chip can’t be thrown as hard or fast as the rock chip, reducing the force of impact against a windshield. Fewer broken windshields are reported in work zones using the ceramic chip.
As wear occurs, porosity of ceramic aggregate results in fresh cells of the material being exposed as aggregate breaks, leaving the surface unchanged, as opposed to polishing rock chip aggregates. The rough surface of the particles results in increased bonding and retention of aggregate in the oil base, reducing flying stones, improving wear and plow resistance and decreases maintenance and repair costs.
Cost of the lightweight aggregate is similar to regular rock chip at usually just a few cents more a square yard. However, less lightweight aggregate is used resulting in less waste and a nominal or no additional cost compared to rock.
A normal chip seal application is expected to last about 5 years, according to WTD Highway Management Specialist Jim McKinnon. The WTD is hoping the Realite section of US 85 will last as many as 7 years, depending on traffic.