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Recycled asphalt pavement (RAP) can be beneficially used as fill in the construction of earth structures such as embankments and retaining structures. Experiments were conducted to evaluate the creep response of compacted RAP under sustained deviatoric stresses. Constant stress, consolidated-drained triaxial tests were performed on 100 mm diameter, compacted RAP specimens at multiple confining stresses and deviator stress levels. The test data displayed classic creep behavior, with clearly identifiable primary and secondary creep observed in all specimens. Tertiary creep and creep rupture were observed in specimens tested at larger deviator stress levels. The creep response of RAP was significant at confining pressures less than about 272 kPa, while the creep response was less severe at larger confining pressures. Upper yield stress levels, representing the deviator stress levels below which creep rupture does not occur, were identified and shown to be confining stress dependent. In general, the creep potential of RAP is significant and should be considered in design. The developed creep models can be used to predict the time-dependent deformation of earth structures utilizing RAP backfill.Key words: creep, recycled asphalt pavement, time-dependent behavior, rupture.

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Soluble sulfate measurement in subgrade soils is an integral part of geotechnical investigations due primarily to sulfate-induced heave distress problems experienced by certain chemically treated sulfate soils. Sulfate measurements will assist engineers in the selection of appropriate soil stabilization methods in construction projects. There are no ASTM test methods that provide sulfate measurements in soils. Current methods including the University of Texas at Arlington (UTA) method, which are based on gravimetric procedures, often provide test results with high standard deviations. A modified UTA method, which was developed by addressing the limitations of the earlier methods, is presented in this paper. This procedure is evaluated for reproducible and reliable sulfate measurements in three artificial soils and one natural soil. The modified procedure provided reproducible sulfate measurements for all soils with coefficients of variations (COV) less than 10%. These results matched with ion chromatography measurements, which indicate that the modified method provided reliable measurements.

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