BACKGROUND

Cracking is a primary mode of distress that creates the need for rehabilitation of asphalt pavements. The several modes of asphalt pavement cracking—thermal, reflection, fatigue, and top-down—are all affected by numerous factors and their interactions. Recent research has evaluated a variety of laboratory tests and models to assess the cracking potential of asphalt mixtures and several are recommended for routine use. As asphalt mix designs become more complex with the use of asphalt modifiers, RAP and RAS, and warm mix asphalt technologies, highway engineers have recognized the need to establish and implement reliable performance tests that can be used to evaluate asphalt mixes and ultimately extend the life of asphalt pavements.

NCHRP Project 09-57, “Experimental Design for Field Validation of Laboratory Tests to Assess Cracking Resistance of Asphalt Mixtures,” developed experimental designs for the ruggedness testing and field validation of candidate laboratory tests to assess the resistance of asphalt mixtures to the four cracking types noted above. Candidate test methods were selected through (a) a critical review of relevant research and state mixture design practices and (b) a workshop with invited experts held in February 2015. The findings and conclusions of the project are summarized in NCHRP Research Results Digest 399, Field Validation of Laboratory Tests to Assess Cracking Resistance of Asphalt Mixtures: An Experimental Design; the contractor’s final project report is available at https://onlinepubs.trb.org/onlinepubs/nchrp/docs/NCHRP09-57_FR.pdf.

OBJECTIVE

The objective of Phases I and II of this research was to determine the ruggedness of laboratory tests identified in NCHRP Project 09-57 as candidates to assess the cracking resistance of asphalt mixtures. Ruggedness testing was conducted per ASTM E1169, Standard Practice for Conducting Ruggedness Tests. The objectives of Phase III were to reassess the availability of materials and pavement performance data of LTPP and 2008 MnROAD field sections originally proposed by NCHRP Project 9-57, identify existing field performance data used for validating ten cracking tests, and recommend the next steps of field validation based on the available materials and field performance data.

STATUS

Phase III completed. The agency's report is available as Web-Only Document 389: https://nap.nationalacademies.org/catalog/27421/ruggedness-of-laboratory-tests-to-assess-cracking-resistance-of-asphalt-mixtures