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This study is based on the principles of thermodynamics and utilizes the Hansen solubility parameter theory and molecular dynamics simulation techniques. By introducing solubility parameters and interaction parameters, modified molecular models for rubber and aged asphalt are constructed. The study systematically investigates the mechanisms underlying the effects of polyphenolic chemical modification and oxidative aging on the performance and compatibility changes of rubber asphalt. The results show that the solubility parameter (δ T) of the asphalt system decreases gradually with increasing temperature. At a temperature of 160 °C, the solubility parameter difference (Δ δ T) between the asphalt and rubber power (RP) is minimized, indicating the highest degree of compatibility between the two materials. After chemical modification, the solubility parameter of the RP increases, the difference in solubility parameter between the RP and asphalt decreases, and the chemical modification improves the compatibility of the two phases. Oxidative aging causes a shift in the composition ratio of asphalt towards asphaltene, leading to an increase in the solubility parameter of asphalt and a larger difference in solubility parameter between the system. As a result, the compatibility of modified asphalt decreases. [ABSTRACT FROM AUTHOR]

The utilization of spent cathode carbon blocks (SCCB) from aluminum electrolysis has become challenging due to their content of highly toxic cyanides and environmentally harmful fluorides. To achieve reliable recovery and utilization of hazardous waste, targeted research has been conducted on the treatment of waste cathode carbon blocks and their potential application in asphalt pavement. Hydrogen peroxide (H 2 O 2) is employed to remove cyanides from the waste cathode carbon blocks, meeting the construction requirements for transportation areas. Anhydrous calcium chloride is used as a calcium source to precipitate soluble fluorides in the solution. Finally, the waste cathode carbon blocks are gel-crosslinked using polyvinyl alcohol-polyvinyl pyrrolidone, addressing the release of fluorides beyond environmental tolerance. This results in the synthesis of a composite material consisting of calcium fluoride deposits and gel-encapsulated waste cathode carbon blocks (PSB), which exhibits good thermal stability in the temperature range of 0–217 °C. Through DSR and MSCR testing, it has been demonstrated that the gel-crosslinked waste cathode carbon block composite material improves the asphalt's sensitivity to temperature and enhances its resistance to rutting at high temperatures. The 1% PSB/SBS modified asphalt shows the best performance, compared to SBS, the complex modulus (G*) of the modified asphalt increased by 117.4% at 46 °C, and the recovery indices for creep at 64 °C improved by 39.28% (at 0.1 kPa) and 55.65% (at 3.2 kPa), and thermal gravimetric analysis of the asphalt confirms that the addition of PSB improves the asphalt's thermal stability. Fluorescence microscopy analysis reveals that the inclusion of PSB does not affect the morphological development of SBS swelling and plays a stabilizing and supporting role in the asphalt mixture. [ABSTRACT FROM AUTHOR]

In this study, microalgae biodiesel (MB) was prepared by chemically modifying microalgae acidified oil, which was in turn added as a modifier to a pre-synthesized crumb rubber-styrene-butadiene-styrene (CR/SBS) modified asphalt to prepare MBCR/SBS composite modified asphalt. Rotational viscosity measurement showed that viscosity of MBCR/SBS-2 asphalt meets the requirements of Superpave specifications. Dynamic shear rheometer and multiple stress creep recovery tests revealed that MBCR/SBS-2 asphalt exhibited the largest complex modulus (G∗), smallest phase angle (δ) in high frequency range, and higher average recovery rate (R) after rotating thin film oven test. The fatigue cracking analysis revealed that higher content of MB results in better resistance to fatigue cracking under intermediate temperature. Separation analysis showed that MBCR/SBS-2 asphalt possessed softening point difference of 2.9 °C. Fourier transform infrared spectroscopy and proton nuclear magnetic resonance spectroscopy analyses confirmed more unsaturated groups in the MB than in the base asphalt, and amide groups bonded to the free radicals of CR which promoted the development of network structure resulting in enhanced mechanical properties of MBCR/SBS modified asphalt than pristine CR/SBS asphalt. In addition, a proposed synthesis and performance mechanism of MBCR/SBS asphalt was elaborated. This study based on simplified preparation and enhanced performance of MBCR/SBS asphalt composite modified asphalt, could be of potential interest for practical applications in construction and highway industries. Image 1 • Microalgae biodiesel (MB) added CR/SBS modified asphalt was prepared. • MBCR/SBS modified asphalt realized lower viscosity than CR/SBS modified asphalt. • MBCR/SBS asphalt exhibited enhanced thermal stability and mechanical properties. • MBCR/SBS asphalt realized excellent viscoelasticity and good storage performance. [ABSTRACT FROM AUTHOR]

The central toxic part of the aluminum industry's overhaul slag, as high value-added recycling of spent refractory material (SRM), contributes to environmental protection and resource recycling. Herein, a "bayberry"-like hexamethyldisilazane-tannic acid-SRM (HMDS-TA-SRM) modifier was prepared by a simultaneous "precipitation-TA wrapping" reaction design and a secondary grafting reaction with HMDS. The design allows the material to be treated with a concentration of F− (5.93 mg/L) that meets the Chinese primary wastewater discharge standard (10 mg/L). HMDS-TA-SRM with hydrophobic (water contact angle = 104.3°) nano-sized microsphere stacking surface exhibited good interfacial interaction with the matrix bitumen. At 64 °C and 0.1 kPa and 3.2 kPa pressures, the deformation recovery capacity of the HMDS-TA modified asphalt was increased by 34.9% and 45.6% compared to that of the pristine SBS-modified asphalt, respectively. At the same time, the double wrapping of the modified film and bitumen significantly improved the sequestration capacity of hazardous substances, with a cumulative F− exudation of only 0.45% after 180 d of immersion. Attributed to the green, cost-effective and efficient modification method, the new SRM-asphalt system could be deemed of great promise for the safe application of SRM. [Display omitted] • A simple simultaneous reaction strategy achieves the high value of highly toxic waste refractory-based asphalt modifiers. • The surface modified film layer of the spent refractory material-based modifier possessed high hydrophobicity. • Spent refractory material-based modifier film added asphalt exhibited better double protection. • The spent refractory material based SBS modified asphalt has better viscoelastic properties and long-term stability. [ABSTRACT FROM AUTHOR]

This study proposes the incorporation of waste steel slag and waste rubber into asphalt to prepare asphalt mastic with increased mechanical properties and can thus concurrently limit environmental pollution from these wastes. The surface of crumb rubber (CR) was activated by NaClO and was then treated with KH550 silane coupling modifier. Dynamic shear rheometer (DSR), multi-stress creep recovery (MSCR) and zero shear viscosity (ZSV) tests were applied explore the high temperature performance of asphalt mastic. The performance of asphalt mastic was analyzed by Burgers model, and the enhancement mechanism was analyzed by Fourier transform infra-red (FTIR) spectroscopy, scanning electron microscopy (SEM), energy dispersive X-ray (EDX), fluorescent microscopy (FM), and X-ray diffraction (XRD). Experimental results showed that coupling modified CR improved the complex modulus (G*) and rutting factor (G*/sinδ) and reduced the temperature sensitivity of asphalt mastic. The coupling modified CR increased the elasticity coefficient E 1 , viscosity coefficient η 1 , relaxation time η 1 /E 1 and delay time η 2 /E 2 of asphalt mastic by 2.8 times, 3.6 times, 1.3 times and 0.9 times, respectively, while steel slag powder (SSP) further enhanced the mechanical properties of the asphalt mastic. FM test showed that coupling modifier CR promoted the swelling of CR and SBS polymer, and hence resulted in a well-developed cross-linked network structure in the asphalt. The positive effect of SSP on the high temperature properties of asphalt mastic suggests that the use of SSP and CR in pavement engineering provides a sustainable solution for the disposal of industrial wastes and the preparation of new asphalt mastic with higher mechanical and thermal properties for practical applications. [Display omitted] • The crumb rubber was modified by secondary treatment. • Burgers model was used to analyze the viscoelastic behavior of asphalt mastic. • The feasibility of CR with steel slag powder in road engineering was demonstrated. • Coupling modified CR promoted the network structure in modified asphalt mastic. • A sustainability analysis of the application of CR and SSP in asphalt was performed. [ABSTRACT FROM AUTHOR]