Optimal distribution of rolling coverage in multiple chip seals

A study investigated the optimal rolling coverage distribution of 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 with the use of two different rolling distributions per seal type (double and triple seals) with no rolling or one rolling for the bottom layer. A 5-ton pneumatic tire roller was used to fabricate these samples in the field. The double seals were composed of granite 78M aggregate for the bottom layer and lightweight aggregate for the top layer. The triple seals were constructed with granite 78M aggregate for both the bottom and middle layers and lightweight aggregate for the top layer using CRS-2 emulsion. The aggregate retention performance was evaluated by the flip-over test, the Vialit test, and the third-scale model mobile loading simulator. It was found that the double seal clearly required rolling for the bottom layer, and the triple seal did not; therefore, the rolling operation may be eliminated for the bottom layer of the triple seal.