The Carbon County Road Department began recognizing the benefits of ESCS lightweight (LW) chip seals after performing a test section in 2013 and completing their first full project with ESCS LW chips in 2016. After the 2017 chip season, when ESCS LW chips were again utilized, the department prepared a Return on Investment (ROI) report noting chip retention increased from 30% to 99% with the ESCS LW chips and achieved an annual estimated savings of over $300,000.
More recently in 2018, Carbon County did a 4.5 mile test section using a fine grade ESCS LW chip as an even greater cost savings tool on a rural section of road near the county airport. LW fine grade chip seals have been used extensively in locations across the United States including North Carolina and Kansas. Jim Thompson of North Carolina-based Stalite Corporation says, “Fine grade chips provide a number of benefits to the user, including less loose aggregate due to a more exact application rate, less tire spray in wet conditions and a quieter riding surface since lightweight aggregate does not reflect tire noise as much as other aggregates.”
Daniel Campbell with the Carbon County Utah Road Department noted that the LW fine grade chips created an excellent wear surface with extremely good skid resistance and found that the chip was embedded so well that no chips were dislodged even in some spots where vehicles had spun their tires or skidded on the section or roadway.
Campbell also noted how quickly and easily they were able to apply them and how much surface area they could cover in one day compared to larger chip sizes. At the time of this article, Carbon County is procuring fine grade chips for a 55-mile section of roadway that will be chipped as part of their 2019 chip seal project.
Major cost savings from fine grade chip applications come from increased coverage rates of the chip and reduced shot rates of the emulsion being applied.
1. The surface area covered with the same volume of aggregate increases proportionally as the material becomes smaller. (The surface area covered with fine chip is often approximately double compared to that of frequently used larger chip sizes.)
2. The shot rate of the emulsion decreases proportionately as the size of the chip gets smaller. (Less emulsion is needed to achieve the desired embedment of the aggregate when the particles are smaller creating a significant cost savings.)
While Carbon County continues to use larger sizes of ESCS LW chip seal aggregate, they have discovered the significant cost savings, as well as the excellent performance, available from the use of LW fine grade chip seal aggregates.