NRRA: Impact of Polymer Modification on IDEAL-CT and I-FIT for Balanced Mix Design

Status:  Complete
Report Date:  03/06/2023


premium mix treatment for high traffic-volume roadways, with an expectation that the extra cost for polymer modification will be justified through enhanced pavement performance. The benefits of polymer modification on pavement performance are well documented, providing a life extension of 5 to 10 years when used with a stable pavement structure. However, several recent studies found that PMA mixtures did not always show better cracking resistance than the unmodified mixtures in new laboratory cracking tests such as the Indirect Tensile Asphalt Cracking Test (IDEAL-CT) and Illinois Flexibility Index Test (I-FIT), which indicated that the additional cost of polymer modification could not provide the expected return on investment. These results contradicted the existing literature and the superior field performance of many existing projects using PMA. There are two hypotheses for these unexpected results. This study will evaluate the two hypotheses with an ultimate objective of better understanding the impact of polymer modification on the IDEAL-CT and I- FIT results for balanced mix design (BMD).

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