Fatigue behavior of fiber-reinforced recycled aggregate base course

An experimental investigation was undertaken to study the flexural fatigue behavior of a stabilized fiber-reinforced pavement base course material composed largely of recycled concrete aggregate with small amounts of portland cement and fly ash. The primary objectives of this endeavor were (1) to evaluate the fatigue resistance of this material; and (2) to determine the extent to which a modest amount of reinforcing fibers (4% by dry weight) can improve the flexural fatigue behavior of this lean cementitious composite. In addition to the repeated load tests, a separate series of static flexural tests and a series of compressive and flexural tests (using notched specimens) were conducted on pieces of failed beams to establish strength correlations to better estimate the static strengths of the specimens; this strength was used to determine the final stress ratio for each beam. The data obtained from this test program showed that a stabilized base course material consisting primarily of recycled aggregate with only 4% cement and 4% fly ash (by weight) has a fatigue strength and endurance limit comparable to virtually all typical stabilized highway materials. The inclusion of 4% (by weight) hooked-end steel fibers significantly improves this material's resistance to fatigue failure. In general, the results of this investigation suggest that a recycled aggregate composite consisting primarily of waste materials has significant promise as a base course for highway pavements.