The SD1999-09 study provided specific recommendations to improve chip seal performance and developed chip seal design and construction guidelines. The study also recommended to construct test sections in the western part of the state using limestone and natural aggregates and to re-evaluate the chip seal performance on SD50 near Yankton, SD. Since quartzite and natural aggregates were tested on the SD1999-09 study, it is necessary to test the new chip seal design and construction guidelines using limestone aggregate. Particle shape is a concern since flat and elongated particles tend to be more susceptible to becoming dislodged causing windshield damage and not being properly embedded in the emulsion. The flakiness index is a measure of the percentage by weight of flat particles. The amount of flat and elongated particles in aggregates currently being used for chip seals in South Dakota is unknown. The Flakiness Index needs to be evaluated for aggregates commonly used for surface treatments in South Dakota.
Minnesota Department of Transportation currently places a fog seal on all chip sealed surfaces. The fog seal aids in chip retention, aesthetics, and reduces damage from snowplows. A fog seal was evaluated as part of the SD1999-09 research study and should be tested on the limestone chip seal.