Optimal Distribution of Rolling Coverage in Multiple Chip Seals.

This paper presents a study to investigate the optimal rolling coverage distribution among different layers of multiple chip seals (double and triple seals). The chip seal samples were fabricated in the field for laboratory testing. The chip seal sections were constructed using two different rolling distributions per seal type (double and triple seals) with no rolling or one rolling for the bottom layer. A pneumatic tire roller or a combination roller was used to fabricate these samples in the field. The double seals are composed of granite 78M aggregate for the bottom layer and lightweight aggregate for the top layer. The triple seals are constructed usinggranite 78M aggregate for both the bottom and middle layers and lightweight aggregate for the top layer using CRS-2 emulsion. The aggregate retention performance is evaluated using the flip-over test (FOT), Vialit test, and the third-scale Model Mobile Loading Simulator (MMLS3). It is found that the double seal clearly requires rolling for the bottom layer, and the triple seal does not; therefore, the rolling operation may be eliminated for the bottom layer of the triple seal.