Performance evaluation of chip seals with polymer-modified emulsions

Chip seals provide a durable and functional pavement surface and serve as a highly economical highway maintenance option when constructed properly. Data and literature suggest that chip seal sections constructed with polymer-modified emulsions (PMEs) provide better initial and long-term performance and also extend the overall service life of pavements. This paper compares the performance of chip seals constructed with PME versus those constructed with non-modified emulsion. The overall performance evaluation is based on aggregate retention performance. Three kinds of emulsion (CRS-2, CRS-2P, and CRS-2L) are used to fabricate samples in the laboratory and in the field. Adhesion of the emulsions is examined using the Vialit test with various curing times and temperature conditions in the laboratory. To evaluate the aggregate retention performance of the chip seals, the Vialit test, flip-over test (FOT), and the third-scale Model Mobile Loading Simulator (MMLS3) are employed. The results from these tests indicate that the PMEs (CRS-2P and CRS-2L) enhance the aggregate retention performance, and do so more significantly in the early stages and at low temperatures. This improvement is due to the fast and improved adhesion of the PME and its ability to enhance the aggregate retention performance at low temperatures.