Stiffness evolution of granular materials stabilized with foamed bitumen and cement

Abstract

From the literature it is possible to find two trends regarding the stiffness evolution of the Foamed Bitumen Stabilized/Recycled mixtures. The first trend indicates that once the foamed bitumen mix reaches a constant value due to curing process, the stiffness decreases with time due to load cycles. The second trend indicates that stiffness remains constant after curing process. In this research, the stiffness evolution of foamed bitumen mixes stabilized with different bitumen and cement contents is studied. The stiffness was measured using the Indirect Tensile Fatigue Test (ITFT). Results indicate that once the foamed bitumen mix reaches a constant value due to curing process, the stiffness will decrease or keeps constant depending on the stress-level applied to the foamed bitumen layer. If the stress-level is lower than a specific value, the stiffness of the mix will remain constant at a value very close to the initial stiffness. If the stress-level is greater than a specific value the stiffness of the mix will decrease gradually. Also, the reduction rate of the stiffness will be greater as the stress-level is higher. The analysis of results from mixes with different bitumen and cement contents allow identifying the effect of both stabilizing agents in the long-term stiffness.