Correlating Rheological and Bond Properties of Emulsions to Aggregate Retention of Chip Seals

The development of binder stiffness and bond strength is critical for new chip seals: loose aggregates must be minimized once a road enters into service. A new test protocol is presented: called the bitumen bond strength (BBS) test for evaluating emulsion setting behavior, the protocol can be used to evaluate aggregate retention and raveling potential of chip seals. The time required for the asphalt emulsion to gain adequate strength and adhesion to aggregate chips depends on aggregate–binder compatibility, environmental factors, and mechanical action. BBS test results demonstrate bond strength development over a full curing interval for a variety of materials and curing conditions. Results obtained using the BBS test are compared with dynamic shear rheometer strain sweep results to investigate a correlation between bond strength and the rutting parameter G*/sin δ. BBS test results are also correlated to aggregate loss as measured by the sweep test. This research may contribute to the ongoing development of specifications for construction and performance properties of asphalt emulsions used in surface treatments.