Frost Resistance and Mechanical Characteristics of Cement-Stabilized Macadam Mixed with Rubber Powder

Abstract

This study aimed to prepare cement-stabilized macadam mixed with rubber powder (CSMR) by replacing the aggregate with rubber powder using the same size with the aggregate of less than 1.7 mm by the equal-volume substitution method. The rubber powder content was 10%, 20%, 30%, and 45% of the aggregate volume (less than 1.7 mm). Combining the unconfined compressive strength test and freeze-thaw cycle test in the laboratory, the frost resistance and mechanical characteristic evolution law of CSMR were studied and analyzed, and the nonlinear stress-strain curve of the material was obtained. The results were as follows: first, the compressive strength of CSMR decreased with the increase in the rubber powder content, and the average unconfined compressive strength of C5P0.1R45 was 1.35 MPa in 7 days, which still met the basic strength requirements of the railway subgrade bed. Second, the frost resistance evaluation index (FRE) decreased first and then increased with the increase in rubber powder content. When the rubber powder content was more than 30%, the CSMR showed better freeze-thaw resistance. Finally, based on the Duncan–Chang hyperbolic model and the strain-softening adjustment coefficient, the mechanical constitutive equation of the material was established and the nonlinear mechanical characteristics of the whole process of CSMR were well described. Meanwhile, the analysis of the material stiffness attribute parameters showed the addition of rubber powder significantly improved the toughness of the material compared with the traditional cement-stabilized macadam. This study was of great significance to further understand the basic mechanical properties of CSMR and to construct load-passing durable railway subgrade structures.