Evaluation of the Shear and Permanent Deformation Properties of Cold In-Place Recycled Mixtures With Bitumen Emulsion Using Triaxial Tests

Abstract

[Abstract] The cold in-place recycling (CIR) technique is a road rehabilitation method suitable for a circular economy. Triaxial tests have proven to be suitable for studying the mechanical behaviour of cold mixtures. In this study, CIR specimens were prepared using a gyratory compactor with different proportions of bitumen emulsion. The Mohr–Coulomb diagrams and shear parameters were obtained by conducting monotonic triaxial tests at different confining pressures. The binder content provided adequate cohesion; however, an excess of binder reduced internal friction. Subsequently, repeated load permanent deformation triaxial tests were performed. Accordingly, critical stress ratios between 20% and 30% were obtained, and the mix with a 2.50% binder exhibited the best response. Lastly, two permanent deformation prediction models were fitted to the measured results. For high deformations, the Paute model underestimated the deformations, whereas the Huurman model demonstrated the best fit.