UTC Center for Highway Pavement Preservation
|Contract Number:||2013-0066 Z11|
|Keywords:||Chip seal, pavement preservation, percent embedment, image processing, sand patch test|
Long-term performance of a chip seal treatment is affected by several factors including the type and morphology of the aggregates, emulsion/binder type and most importantly, the mictrostructural characteristics such as the percent embedment and aggregate orientation. As part of a previous MDOT project (OR15-508), a methodology (and a software named CIPS) was developed to directly calculate the aggregate percent embedment based on digital image analysis. The most important aspect of this methodology is that it involves direct calculation of the embedment of individual aggregates from the images of vertical saw-cut slices. The CIPS methodology does not suffer from the major drawbacks of the traditional methods of estimating percent embedment (i.e., sand patch and laser-based methods), which assume the pavement surface to be perfectly smooth, ignore penetration of aggregates into the substrate and ignore the aggregate size distribution and orientation. The CIPS methodology provides the percent embedment objectively; however, the appropriateness of the computed percent embedment for a given field application could not be assessed due to a lack of data relating the percent embedment to chip seal performance. The primary objective of this study was to relate the image-based percent embedment to performance measures such as resistance to bleeding and chip loss. To meet this objective, an extensive laboratory testing program was completed. This included tests for chip loss and bleeding using a retrofitted Hamburg Wheel Tracking (HWT) device. Two emulsion types (CRS-2M and CSEA), one binder (PG70-28) for hot-applied chip seal application, and three aggregate sources (one slag and two different kinds of natural aggregate) were included in the testing program. Digital image techniques of the CIPS methodology were utilized to quantify and analyze the laboratory test results to develop the percent embedment thresholds. Finally, pay adjustment factors and procedures for chip seals were developed based on the percent embedment thresholds.
|MDOT Research Manager||MDOT Project Manager||Performing Organization(s)|
|Mark Polsdofer||Robert Green||MSU|