Laboratory Evaluation of Asphalt-Rubber Gap Graded Mixtures Constructed on Stockholm Highway in Sweden

Authors: Kamil E. Kaloush, Krishna P. Biligiri, Thorsten Nordgren, Waleed A. Zeiada, Maria C. Rodezno, Mena I. Souliman, Jordan Reed, Jeffrey Stempihar



The objective of this study was to conduct an advanced laboratory experimental program to obtain typical engineering material properties for reference, asphalt-rubber (AR), and polymer-modified (PM) gap graded asphalt concrete mixtures placed in the Stockholm area of Sweden. The advanced material characterization tests included: Dynamic (Complex) Modulus for stiffness evaluation; triaxial shear strength test to evaluate shearing resistance; repeated load for permanent deformation characterization; beam fatigue for crack evaluation; Indirect Diametral Tensile test for thermal cracking mechanism evaluation; and C* Integral test to assess crack growth and propagation. Furthermore, conventional binder consistency tests were performed to complement other material mixture characteristics. The data was used to compare the performance of the AR gap graded mixture with respect to reference and PM gap graded mixtures. The results showed that the AR gap graded mix would provide better resistance to low temperature cracking and permanent deformation. The expected fatigue life for the AR gap graded mixture was higher than the reference and PM mixtures for the existing highway conditions. Furthermore, the crack propagation tests showed that the AR gap graded mixture had highest resistance to crack propagation than the other two mixtures.

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