In this paper, the effects of Layered Double Hydroxides (LDHs) incorporation on the ageing resistance and self-healing properties of asphalt binder were studied. Matrix asphalt (MA) and LDHs modified asphalt (LMA) binders were aged by short-term thermal oxidation and ultraviolet ageing and their ageing performance was characterized through the analysis of the SARA fractions and temperature sweep test. Frequency sweep test and capillary flow test were conducted to characterize the fluidity of the asphalts, and fatigue life recovery test was used to characterize the asphalt self-healing properties. The main results indicate that under the same ageing conditions, the light component contents of LDHs modified asphalt are higher than that of matrix asphalt and the complex modulus increment of LMA is lower than that of matrix asphalt. It means that LDHs modified asphalt has better anti-ageing performance. Besides, LDHs modified asphalt has higher fluidity and lower self-healing threshold temperature than matrix asphalt binder under the same ageing conditions, indicating that the incorporation of LDHs can effectively retard the reduction of asphalt flow capacity due to ageing. It was also found that asphalt binder containing LDHs had better self-healing potential due to the improvement of the ageing resistance. It was concluded that the addition of LDHs can effectively improve the ageing resistance and self-healing properties of asphalt binder.

Layered double hydroxide (LDH) could improve the aging resistance of an asphalt binder. However, the previous work all arbitrarily selected only one dosage of LDH such as 3% or 5%, which could not be enough to know the effect of LDH and its dosage on the pavement performance and aging resistance of an asphalt binder accurately, it is important to investigate the LDH effect on the properties of asphalt from more widely ranges of dosages. Meanwhile, the LDH and asphalt binder interaction is still unclear. In this paper, six dosages (from 2% to 7%) of Mg-Al-CO32−-LDH were conducted to modify the styrene-butadienestyrene modified asphalt (SBS MA). The Fourier transform infrared spectroscopy (FTIR) and X ray diffraction (XRD) results indicate that there is no chemical reaction between LDH and SBS MA, the blending of LDH and SBS MA is a physical way. The rheological properties of SBS MA are studied by both dynamic shear rheometer (DSR) and bending beams rheometer (BBR), the results show that LDH can improve the high temperature performance of SBS MA, and does not significantly weaken other properties of SBS MA by controlling LDH dosage to be lower than 4%. The FTIR, complex modulus and VAI results show that LDH can significantly improve both the thermal oxide aging and UV aging resistances of SBS MA. LDH dosage of 4% is suggested to be the optimal dosage after considering the effect of LDH on the aging resistance and pavement performance of asphalt binder.

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.

Most researchers ignored the differences of spectrum of ultraviolet (UV) lamp when ageing bitumen. The effects of different wavebands of UV radiation on bitumen are studied in this paper. DSR results indicated that rheological properties of bitumen are not closely related to the ageing time when sample thickness is 1.13 mm. FTIR results illustrated that reactive sulfur atoms are completely oxidized before carbon atoms. Furthermore, the ageing effect on bitumen is highest with UV radiation ranging from 300 to 350 nm, medium with UV radiation ranging from 260 to 300 nm and lowest with UV radiation ranging from 350 to 400 nm. Consequently, different types of UV lamp give rise to different ageing effects on bitumen. (C) 2017 Elsevier Ltd. All rights reserved.