Toward Statewide Implementation of the Surface Performance Graded Specification for Chip Seal Binders
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Over the past 15 years, a surface performance-graded (SPG) specification for chip seal binders was developed by the Texas Department of Transportation (TxDOT) using laboratory measurements and visual field performance (aggregate loss and bleeding) of 75 highway sections (HSs). The SPG was established in an effort to extend the service life of chip seals by providing a binder selection method that accounts for differences in climate. TxDOT recently commenced a statewide implementation effort of the SPG specification. The initial activities include (a) reviewing laboratory and field performance of HSs built in 2011 based on the latest version of the SPG specification, newly generated SPG requirement map, and revised surface condition index calculation; (b) characterizing binders from HSs built in 2013 and monitoring their field performance; (c) proposing additional parameters to complement the SPG specification; and (d) predicting bending beam rheometer (BBR) creep stiffness values from frequency sweep results. When comparing the expected performance of the binders (based on their SPG grade) against actual field performance after the first year in service, 80 percent of the HSs built in 2011 correlated well. Individual SPG properties were compared to corresponding field performance for 2013 chip seal binders in terms of aggregate loss or bleeding. Unexpected field performance from the Amarillo District largely contributed to poor correlation between the BBR creep stiffness properties and field performance in terms of aggregate loss for 2013 HSs. A phase angle parameter was introduced in the SPG specification to ensure modified binders contain sufficient polymers. The prediction of BBR creep stiffness values via a frequency sweep test was not reliable at colder temperatures, even when a 4-mm dynamic shear rheometer plate test was used.
Chang, Shi (2015). Toward Statewide Implementation of the Surface Performance Graded Specification for Chip Seal Binders. Master's thesis, Texas A & M University. Available electronically from