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Layered double hydroxides (LDHs) with different particle sizes (75 nm, 115 nm, 180 nm and 300 nm which were marked with LDHs-75, LDHs-115, LDHs-180 and LDHs-300) were characterized by scanning electron microscope, UV–vis reflection and absorption spectrophotometer and laser scatter meter. Furthermore, this paper investigated the influence of LDHs with different particle sizes on the rheological properties of bitumen before and after ultraviolet aging by temperature susceptibility test, dynamic shear rheometer test (DSR) and IR spectra test (FTIR). The researches reveal that LDHs-180 hold the strongest UV shielding performance. The temperature susceptibility of pristine bitumen and LDHs-75, LDHs-115, LDHs-180, LDHs-300 modified bitumen after aging decreased by 9.01%, 6.36%, 3.98%, 2.15% and 5.49%, respectively, which indicate LDHs-180 is more beneficial to weaken the decrease of bitumen temperature susceptibility after aging. Similarly, LDHs-180 modified bitumen show less variation in rheological properties than other bitumen samples after aging. This implies that LDHs-180 could mitigate the influences of UV aging on the rheological properties of bitumen more availably. In addition, the FTIR analysis further shows that the carbonyl and sulfoxide index of LDHs-180 modified bitumen is the smallest after aging, which indicates LDHs-180 is more helpful for improving bitumen anti-UV aging properties than that of LDHs-75, LDHs-115 and LDHs-300.

Layered double hydroxides (LDHs) have been alternatively employed to improve the ultraviolet (UV) aging resistance of bitumen due to their high UV reflectance, but LDHs particles cannot be dispersed into bitumen uniformly and stably since their poor compatibility with bitumen. Therefore, the problem of poor compatibility must be solved before its application. Generally, organic modification can change the surface characteristics of inorganic particle and then improve the compatibility. The objectives of this work are to evaluate the effect of prepared various organic LDHs on the anti-UV aging property of bitumen and then determine an optimal organic LDHs for bitumen modification. For these purposes, three organic anions, sodium dodecyl benzenesulfonate (SDBS), sodium dodecyl sulfate (SDS) and sodium dodecyl sulfonate (SDSO), were used as organic modifiers to prepare organic LDHs (OCLDHs), then the storage stability and anti-UV aging of OCLDHs modified bitumen were investigated. Experimental results show the organic modification can suppress the separation phenomenon of OCLDHs modified bitumen during the high temperature storage, indicating the compatibility and stability of the mixture is ameliorated. Compared with LDHs modified bitumen, OCLDHs modified bitumens show lower aging degree during UV exposure, which indicates that OCLDHs exhibit better effect in enhancing the anti-UV aging performance of bitumen. FTIR analysis indicates that OCLDHs effectively retard the formations of oxygen-containing functional groups and aromatic structure of bitumen. Furthermore, SDBS is a preferable modifier for the preparation of organic LDHs due to the most effective improvement in compatibility with bitumen and UV aging resistance of bitumen as compared with SDS and SDSO.

As time goes on, more and more waste SBS modified bitumen mixture (SMBM) located at the top-layer of high-grade roadway requires to be recycled for repaving with high-quality performance. To solve the problem, the reactive rejuvenating systems (BUDGEs and BUDGE-MDIs) containing 1,4-butanediol diglycidyl ether (BUDGE) and/or diphenyl methane diisocyanate (MDI) and fluid catalytic cracking slurry (FCC slurry) are applied to the rejuvenation of aged SMBM. In this paper, the effects of BUDGEs and BUDGE-MDIs on the moisture damage, rutting performance, low-temperature flexural characteritics and the macroscopic fracture morphology of aged SMBM are systematically investigated. The results of the moisture damage suggest that the reactive rejuvenating systems, particularly BUDGE-MDIs, can obviously contribute for improving the water stability approaching to the level of the fresh SMBM and effectively retain the higher water resistance after secondary immersion. The results of the rutting performance demonstrate that BUDGE-MDIs can inhibit the significant reduction of the elastic components of the aged binder and preferably remains the dynamical stability at high temperature when compared with BUDGEs. The low-temperature performance indicates that BUDGE-MDIs has remaining positive effects on the low-temperature crack behavior depression of aged SMBM in comparison with BUDGEs, and the anti-crack ability somewhat deteriorates after long-term loads, while from the fracture morphology, it finds the reactive rejuvenating systems can recover the combining force of aged binder to some extent for the marked reduction in the brittle fracture of aged SMBM at low temperature.

The excellent comprehensive performance of SBS modified bitumen (SMB), during a long-term thermo- and photo-oxidative exposure, will fail to satisfy the pavement requirement. In this paper, the synergistic effect of 4,4′-diphenylmethane diisocyanate (MDI) and 1,4-butanediol diglycidyl ether (BUDGE) on the molecular weight of aged SBS was firstly studied, through a simulation, to confirm whether a new polymer structure can be obtained. Then, the reactive rejuvenating system containing MDI, BUDGE and bituminous composition returning agent (MDI-BUDGEs) was applied in the rejuvenation of aged SMB. The results show that the rebuilt molecular structure of aged SBS can be obtained with the combination of MDI and BUDGE. Meanwhile, MDI-BUDGEs can improve the low-temperature ductility and inhibit the sharp fall of the softening point of aged SMB, while decrease the viscosity-temperature response at 120–165 °C. Also, MDI-BUDGEs can contribute for increasing the viscous component, improving the fatigue resistance and remaining the high-temperature performance grade of aged SMB, and moreover, decrease the limited elastic modulus and the elastic-plasticity transition rate to avoid the occurrence of the brittle failure within a small strain range.

Layered double hydroxides (LDHs) etched by nitric acid was characterized by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), zeta potential potentiometer, scanning electron microscopy (SEM) and ultraviolet and visible (UV–Vis) spectrum. TEM suggests that etching treatment causes the formation of some defects on the surface of etched LDHs and XPS shows that some hydroxyl groups are eliminated from the surface of LDHs after etching. The zeta potential of LDHs is enhanced from 12.02 mV to 17.21 mV for etched LDHs, which suggests etching treatment of LDHs can enlarge repulsion force between particles of LDHs. SEM confirms that the etching treatment is helpful to reduce the agglomeration of LDHs. UV–Vis curves indicates that the absorption UV capacity of LDHs is significantly improved by etching treatment. Moreover, the impact of etching treatment on the physical properties and dynamic rheological characteristics of LDHs modified bitumen during the process of aging was thoroughly investigated. Investigation results indicate that the etching treatment of LDHs is favorable for improving the ductility of LDHs modified bitumen. And the etched LDHs modified bitumen shows the smaller variations of physical properties and dynamic rheological properties as well as structural indexes after UV aging than those of LDHs modified bitumen, revealing that etched LDHs is more beneficial to enhance the anti-ultraviolet aging properties of bitumen since the improvement of dispersity and UV shielding capability of LDHs after etching.

This paper mainly investigates the effect of the reactive rejuvenator diphenyl methane diisocyanate (MDI) and 1,4-butanediol diglycidyl ether (BUDGE) on chemical structures of aged SBS and rejuvenated structures, rejuvenation mechanisms, physical and rheological properties of UV-aged SBS modified bitumen (SMB). Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) show the hydroxyl and carbonyl groups have formed on aged SBS, which indicates that the broken-chain structures of SBS have formed after UV radiation. Meanwhile, the disappeared hydroxyl groups and formed amide bond in FTIR spectrum of MDI rejuvenated SBS, and the associated hydroxyl groups and another appeared carbonyl groups in FTIR spectrum of BUDGE rejuvenated SBS indicate MDI and BUDGE can act as a “bridge” to connect the broken-chain SBS together at 150 °C. Moreover, the performance results show rejuvenation temperature and time have little impact on the physical properties of rejuvenated SMB whatever the rejuvenator is selected. With the increasing content of MDI, the softening point of rejuvenated SMB can be improved and the ductility at low temperature remains almost unchanged. However, the softening point of rejuvenated SMB decreases and the ductility increases as the rising content of BUDGE. Phase angle results indicate MDI can further increase the elasticity of aged SMB, and BUDGE can to some extent restore the viscosity characteristic. From the results of fatigue and rutting performance, 1% BUDGE weakens the fatigue limit temperature of aged SMB from 20.1 °C to 14.9 °C and 1% MDI increases the rutting limit temperature from 79.6 °C to at least 80 °C, which indicates BUDGE and MDI can respectively help improve the fatigue resistance and rutting resistance. Based on the analysis of FTIR spectra and the relative functional group indexes, the results show the increasing concentration of I NH CO in MDI rejuvenated SMB and I C O C in BUDGE rejuvenated SMB, indicating the chemical reaction between reactive rejuvenators and aged SMB can be occurred. The rejuvenation of aged SMB with MDI or BUDGE abides by the addition reaction mechanism or condensation reaction mechanism.

To cater for the concept of global green development, it is of importance, in the bituminous road domain, to achieve the objective of the high-quality rejuvenation of waste bitumen. This paper investigates physical properties, rheological properties, morphology and molecular structure of rejuvenated SBS modified bitumen (SMB) with 1, 4-butanediol diglycidyl ether (BUDGE) or trimethylolpropane triglycidyl ether (TMPGE). The results of physical properties indicate that BUDGE and TMPGE can both improve the low-temperature ductility and penetration of aged SMB, and by contrast, BUDGE can make the aged SMB more flexible at low temperature. From the rheological properties, BUDGE or TMPGE can help restore the crack resistance at low temperature and somewhat decrease the rutting resistance at high temperature, which relies on the reduction of fatigue factor and rutting factor of aged SMB. FTIR spectra and fluorescence images show that the original structure of SBS can be partly rebuilt through the chemical reaction between the terminal groups on BUDGE or TMPGE and the oxygen-containing reactive groups on degraded SBS.

Triethoxyvinylsilane surface organic modified layered double hydroxides (TEVS-LDHs) were prepared and applied to improve the ultraviolet aging resistance of bitumen. The effect of TEVS-LDHs and LDHs on the temperature susceptibility and rheological properties of bitumen before and after UV aging were thoroughly investigated. The storage stability test showed that the difference in the softening point (ΔS) of LDHs modified bitumen (the LDHs content at 2%) decreased from 1 °C to 0.4 °C after TEVS surface organic modification, and the descending trend was more obvious with the content of LDHs increase, which implied that TEVS-LDHs dispersed better and existed more stably in bitumen than LDHs. The introduction of TEVS-LDHs significantly alleviated the temperature susceptibility of bitumen and increased the rutting factor (G ∗ /sin δ) of bitumen, indicating that TEVS surface organic modification were favorable to the improvement of high-temperature performance for LDHs modified bitumen. After UV aging, bitumen became more hard and brittle, compared with LDHs, the addition of TEVS-LDHs alleviated obviously the deterioration tendency of bitumen, which suggested that LDHs surface organic modified by TEVS were far superior to unmodified LDHs in enhancing the UV aging resistance of bitumen.

Ion chelator is a novel crystalline additive which can chelate Ca2+ and migrate in concrete to promote self-healing of surface crack and internal pore. In order to further explore the effect of ion chelator on hydration process of cement, the hydration heat, chemically bound water, compressive strength, hydration products, pore-size distribution and microstructure of cement paste with ion chelator were investigated in this paper. Results of the experiments showed that the ion chelator accelerated the hydration of the cement paste. Incorporation of ion chelator in cement greatly enhanced the chemically bound water content and the mechanical property. Compared with control cement paste, the chemically bound water content and compressive strength of cement paste with 0.5 wt% ion chelator increased by 13.3% and 16.8% after curing for 28 days. According to the DTA-TG and XRD tests, the ion chelator can promote the hydration of C3S and C2S, which was conducive to the generation of calcium silicate hydrate gels. Furthermore, the addition of ion chelator improved the pore-size distribution and microstructure of cement paste, and a large number of floccules and needles appeared in the pores of cement paste.

The increasing reclaimed asphalt pavement mixture causes environmental pollution and a waste of resource, which could be resolved by the asphalt recycling technology. In this paper, corn oil, waste engine oil, vacuum stream oil and cashew shell oil are used for rejuvenating aged SBS modified asphalt (ASMA), and the effect of composition, structure and thermal-oxidative stability of recycling agents on the early and long-term performance of rejuvenated binder are thoroughly investigated. The results indicate cashew shell oil with nut phenol derivatives has the best rejuvenating effect on ASMA, corn oil containing aliphatic hydrocarbons is more conducive to improving the low temperature performance of rejuvenated ASMA, and vacuum stream oil containing nonpolar alkane compound shows the worst regeneration effect. Meanwhile, simultaneous thermal analysis reveals nonpolar aliphatic hydrocarbons vacuum stream oil has the poorest thermal stability for its lowest initial decomposition temperature 146 °C, while initial decomposition temperature of cashew shell oil and corn oil are all over 200 °C. The changes of physical and rheological properties of cashew shell oil rejuvenated ASMA after aging are much smaller than that of others, which indicates cashew shell oil with excellent thermal-oxidative stability is more conductive to inhibiting the transition from viscosity to elasticity of rejuvenated binder in the aging process. While vacuum stream oil rejuvenated ASMA shows the most serious aging degree, suggesting the poor thermal-oxidative stability of recycling agents has adverse effects on the anti-aging properties of rejuvenated binder. Infrared spectrum analysis indicates the aging index growth rate of cashew shell oil rejuvenated ASMA is the smallest, also demonstrating the best aging resistance of cashew shell oil rejuvenated ASMA. The correlation coefficients between sulfoxide index and physical-rheological properties are almost all higher than 0.90, while that between sulfoxide index and physical-rheological properties are lower than 0.71, therefore sulfoxide index can be a better indicator for estimating the physical-rheological properties of rejuvenated SBS modified bitumen in the service.

Two different types of UV absorbents, 2-hydroxybenzoic acid and 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid, were intercalated into layered double hydroxides (LDHs) to synthesize organic LDH by anion-exchange method, and then the synthesized organic LDHs were applied to modify bitumen aiming to improve UV aging resistance of bitumen. According to the characterization with X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and scanning electron microscopy (SEM), the two UV absorbents were successfully intercalated into the galleries of LDH, leading to the expansion of interlayer distance of LDH. Thermogravimetry and differential scanning calorimetry (TG–DSC) and UV–vis absorbance analyses indicated that the thermal stability and UV absorptive ability of UV absorbents were enhanced significantly. Compared with LDH, organic LDH exhibited better improvement in UV aging resistance of bitumen by restraining the oxidation of bitumen and generation and stacking of asphaltenes cluster during UV exposure, which was due to the enhanced UV absorptive ability of organic LDH and compatibility between organic LDH and bitumen.

Organic expanded vermiculites (OEVMTs) were prepared using cetyltrimethyl ammonium bromide (CTAB) and octadecyl dimethyl benzyl ammonium chloride (ODBA) as intercalation agents. Effect of EVMT organic modification on physical and aging properties of styrene–butadiene–styrene (SBS) modified bitumen was investigated. The microstructures of the binders were characterized by X-ray diffraction (XRD) and atomic force microscopy (AFM), respectively. EVMT/SBS modified bitumen forms a phase-separated structure, while OEVMT/SBS modified bitumens form the exfoliated nanostructures according to XRD analysis. OEVMTs show the more obvious influence on physical properties of SBS modified bitumen in comparison with EVMT. The compatibility between the EVMT and SBS modified bitumen is also improved after organic modification of EVMT. AFM analysis indicates that the contrast between the dispersed phase and the matrix phase in SBS modified bitumen increases with the addition of ODBA-EVMT. As a result of thin film oven test (TFOT), the viscosity aging index of SBS modified bitumen decreases, while the retained ductility and penetration increase obviously with the introduction of EVMT and OEVMTs. ODBA-EVMT/SBS modified bitumen has more pronounced improvements in aging resistance of SBS modified bitumen in comparison with CTAB-EVMT/SBS modified bitumen by preventing the phase-separated trend of the SBS modified bitumen during TFOT.

Organo-montmorillonite(OMMT)/Styrene-butadiene-styrene(SBS) modified bitumen nanocomposites were prepared by melt blending. The microstructures of OMMT/SBS modified bitumen were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and atomic force microscopy (AFM), respectively. The effect of OMMT on ultraviolet (UV) aging properties of SBS modified bitumen was investigated. FTIR and XRD analyses indicate that the OMMT/SBS modified bitumen forms an intercalated structure. It is observed that the phase contrast between the dispersed domains and the matrix is inverted in SBS modified bitumen, which is decreased with the introduction of OMMT according to AFM analysis. As a result of UV aging, both viscosity aging index and softening point increment of OMMT/SBS modified bitumen decrease significantly. There is a single phase trend in the morphology of the bitumen after aging, which is accelerated by the existence of SBS. However, these changes can be effectively prevented under the influence of OMMT, indicating the good UV aging resistance of OMMT/SBS modified bitumen.