Effect of Mix Parameters on the Dynamic Mechanical Properties of Cement Asphalt Mortar

In this paper, the effects of key mix parameters, including asphalt-cement ratio (A/C), water-cement ratio (W/C), and sand-cement ratio (S/C), on the dynamic mechanical properties of the cement asphalt (CA) mortar used in the ballastless slab track of high-speed rail were investigated by dynamic mechanical thermal analysis (DMTA). Results showed that storage modulus (E) increased with increased S/C ratio and decreased A/C and W/C ratios. The damping ability of CA mortar, which is characterized by tan, increased with increased A/C and W/C ratios. In comparison with Type-II CA mortar which has a lower A/C ratio, tan of Type-I CA mortar with a higher A/C ratio presented a different dependency on the S/C ratio. Relationships between dynamic mechanical properties (E and tan) and volume fraction of phases in CA mortar were quantitatively established.