Effect of strain level on the stiffness of cold recycled bituminous mixtures

Cold recycling is a sustainable technology for the rehabilitation of bituminous pavements. This study investigates the stiffness response of cement-bitumen treated materials (CBTM) manufactured with 80% reclaimed asphalt and treated with 2.0% Portland cement and 4.0% bitumen emulsion. Indirect tensile stiffness modulus tests were carried out to assess the strain dependence of stiffness at target horizontal deformation levels between 2 and 15 microme-ters. Ultrasonic pulse velocity was also measured to evaluate stiffness at very low strain level. The tests were carried out at three temperatures (5, 20, 35 °C) on CBTM specimens with 14 % of voids. The results showed that the CBTM stiffness decreased with increasing deformation level. Small-strain results can be used to estimate the linear viscoelastic response whereas damage can be observed when the deformation level is increased.