Laboratory and field evaluation of sodium stearate organically modified LDHs effect on the anti aging performance of asphalt mixtures

To improve the compatibility of layered double hydroxides (LDHs) with asphalt binders, the sodium stearate was used to organically modify the LDHs (SS-LDHs). In order to investigate the improvement effects of LDHs and SS-LDHs on the aging resistance of asphalt mixtures in laboratory and field, two kinds of aging simulating tests were conducted in laboratory and a test road was paved with LDHs and SS-LDHs modified asphalt mixtures, respectively. The chemical structure and viscosity of asphalt binders reclaimed from asphalt mixtures were tested by Fourier transform infrared spectroscopy and Brookfield viscometer respectively to investigate the LDHs and SS-LDHs effects on the anti aging properties of asphalt mixtures. Finally, the semi-circular bending test was conducted by universal testing machine to test the blending strength and fatigue life of asphalt mixture before and after aging. The results show that, at the same aging condition, the carbonyl index and viscosity aging index of reclaimed asphalt binders with LDHs or SS-LDHs are lower than that of reclaimed asphalt binders without LDHs and SS-LDHs, while the styrene-butadienestyrene index is higher, the increment of semi-circle flexural strength and the reduction of fatigue life is less than that of asphalt mixtures without LDHs and SS-LDHs, which indicates that LDHs and SS-LDHs can improve the anti thermo-oxidative aging and anti UV aging performance of the asphalt mixture. In comparison, the improvement effect of SS-LDHs on the anti aging performance of asphalt mixture is much better than that of LDHs.