Effect of aging on the dynamic mechanical properties of cement emulsified asphalt mastic

The constitutive equation of cement asphalt emulsified mastic (simplified as the composite mastic) was established based on Burgers model revised by fractional derivative. Combined with aging test and frequency scanning test of composite mastic of various mix proportions, the effects of aging time and mix proportion on the viscoelastic mechanical parameters of the composite mastic were analyzed. Study shows that with aging time increasing, both of the storage modulus and loss modulus of the composite mastic increase. The increase speed of the storage modulus and loss modulus are high during 0-8 h of aging, and then slow down after 8 h of aging. For the composite mastic at mass ratio of emulsified asphalt to cement (m_A/m_C) of 1.2 and 1.4, the phase angle decreases with the increase of aging time at different load frequencies. For the composite mastic at m_A/m_C of 1.0, the phase angle shows a rule of increasing first and then decreasing with the increase of aging time. With aging time increasing, the composite mastic tends to show mechanical properties like elastic materials. The Burgers model revised by fractional derivative can describe the viscoelastic dynamic mechanical behavior of the composite mastic after aging well, and the model parameters elastic modulus E₁, viscosity η₁ and fractional derivative r can describe change rules of the viscoelastic properties of the material in the case of aging well.