The role of lignin and lignin-based materials in sustainable construction - A comprehensive review.

Hydrated lime (HL) is an active filler in some bitumens. Rheological models demonstrate that HL interacts with certain bitumens to develop an adsorbed (interactive) layer around the HL particles. The volume of this layer can be substantial, causing HL to have a much more substantial effect on the bitumen than inert fillers. The level of interaction between HL and bitumen is bitumen dependent. This interaction causes HL to strongly affect high-temperature rheology in certain bitumens, but it has less of an effect in others. The low-temperature stiffening effects of HL are less prominent, and a significant level of fracture toughening (at low temperatures) occurs through the addition of HL. The active nature of HL with certain bitumens is further verified by nuclear magnetic resonance. HL is considered a multifunctional additive with potential benefits to the binder and to the mixture that include resistance to deformation, low-temperature fracture toughening, and increased resistance to age hardening. HL may be competitive with some polymer additives.

Effect of hydrated lime on rheology, fracture, and aging of bitumen. Discussion. Authors' closure

Aging during construction and in-service substantially changes the chemical composition and physical properties of bitumen thereof influences the performance of asphalt pavements. The modification of bitumen by crumb rubber modifier (CRM) significantly increases the complexity of the aging mechanism and is expected to improve the aging resistance of bitumen. This study aims to investigate the effects of laboratory short-term and long-term aging on the chemistry and rheology of crumb rubber modified bitumen (CRMB). Neat bitumen and CRMB with four different CRM contents were studied. Fourier transform infrared spectroscopy and dynamic shear rheometer were employed to measure the change in the chemical composition and rheological properties of binders at different aging states. Bitumen hardening, which was rheologically revealed by the frequency sweep and multiple creep recovery test results, was also reflected in the growth of carbonyl and sulfoxide functional groups. In addition, the aliphaticity and aromaticity indices of binders before and after aging were also investigated. CRMB binders showed improved aging resistance compared to neat bitumen as reflected by the decreased carbonyl and sulfoxide indices as well as the lower change in rheological parameters. Higher resistance against aging was achieved when increasing the CRM content. The results also highlight the correlation between chemistry and rheology of bitumen. Among six selected mechanical parameters of binder, the non-recoverable creep compliance and percent recovery show better correlations with the combined chemical aging index (sum of carbonyl and sulfoxide indices) than the parameters derived from the linear viscoelastic region.

/pdf/effect-of-laboratory-aging-on-chemistry-and-rheology-of-2ik8kccmvo.pdf

Effect of laboratory aging on chemistry and rheology of crumb rubber modified bitumen

Effects of rubber absorption on the aging resistance of hot and warm asphalt rubber binders prepared with waste tire rubber

Rubber asphalt modified with waste cooking oil residue: Optimized preparation, rheological property, storage stability and aging characteristic

https://repository.tudelft.nl/islandora/object/uuid%3Afb92d00c-86f3-4fe7-ac39-eb5f81cce7d4/datastream/OBJ/download

Fatigue performance of long-term aged crumb rubber modified bitumen containing warm-mix additives

As bitumen oxidizes, material stiffening and embrittlement occur, and bitumen eventually cracks. The use of anti-oxidants, such as lignin, could be used to delay oxidative aging and to extend the lifetime of asphalt pavements. In this study, the chemical and rheological effect of lignin on bitumen was evaluated by using a single dosage organsolv lignin (10 wt.% dosage). A pressure aging vessel (PAV) was used to simulate the long-term aging process after performing the standard short-term aging procedure, and the lignin-modified bituminous binders were characterized by an environmental scanning electron microscope (ESEM), Fourier-transform infrared (FTIR) spectroscopy, and a dynamic shear rheometer (DSR). From the ESEM results, the uniform microstructure was observed, indicating that the addition of lignin did not affect the worm structure of bitumen. Based on the FTIR test results, lignin-modified bitumen showed that a lower number of carbonyl and sulfoxide compounds were generated after aging than for neat bitumen. Based on the linear amplitude sweep (LAS) results, the addition of lignin slightly reduced the fatigue life of bitumen. From the frequency sweep results, it showed that lignin in bitumen acts as a modifier since the physical interaction between lignin and bitumen predominantly affects the material rheology. Overall, lignin could be a promising anti-oxidant due to its economic and environmental benefits.

https://www.mdpi.com/1996-1944/12/24/4176/pdf

Chemical and Rheological Evaluation of Aged Lignin-Modified Bitumen

In-depth understanding of the synergetic effect between the various incorporating constituents in asphalt binders (e.g., polymers, fillers) is needed to design durable paving materials with desired properties. In this research, the focus was first on the effect of the reactivity of fillers on the evolution of adhesive strength between stone aggregates and epoxy modified asphalt mastics during the epoxy polymerization. Uniaxial tensile tests were performed on different combinations of fillers and binders with and without the epoxy-based polymer, and at different modification levels. Based on the results of the tensile tests, the increase of the adhesive strength of mastic with aggregates was generally lower when reactive filler particles (i.e., hydrated lime) were added than of epoxy binders with non-reactive filler. In other words, the non-reactive fillers did not influence the adhesion process and were thus selected for the next step studies on aging. The chemo-mechanical changes of epoxy modified asphalt mastics were analysed after pressure aging vessel and oven-conditioning after various aging times by means of Fourier transform infrared spectroscopy and dynamic shear rheometer. Less sulfoxides formed and higher modulus levels were measured with increasing the epoxy polymer in mastics over oven- and PAV-aging conditions. Due to the pressure difference, the rate of modulus increases and phase angle decrease was higher when the materials were conditioned in PAV than in oven.

/pdf/evaluation-of-epoxy-modification-in-asphalt-mastic-158j5wt0yl.pdf

Evaluation of epoxy modification in asphalt mastic

The addition of epoxy modifier in bitumen is a relatively new modification technology (1-4) and the most critical epoxy polymerization-induced changes of the epoxy-bituminous materials are not fully understood. Different phenomena take place when epoxy modifiers are incorporated into bitumen and they are dependent on the material hardening conditions. Temperature is one of the most crucial parameters that influences to the development of physical, chemical and mechanical characteristics at the early life (curing or chemical hardening - CH) (5-7) and long-term service (oxidative hardening - OH) (4) of epoxy-modified binders. For this reason, in-depth exploration of epoxy chemistry in bitumen is needed to understand the evolution of the properties of these binders in time. Within this framework, the chemical compounds and their reaction products generated under various conditions were studied to reveal the time dependency of molecular microstructures of modified binders. Special attention was given to the evaluation of physiochemical characteristics and the mechanical properties of epoxy-bituminous binders, concluding that the degree of CH and OH was dependent on the level of epoxy modification in bitumen. It was observed that the sulfoxide compounds are the most representative index for assessing the age hardening of epoxy-modified bitumens. Finally, the enhanced resistance against environmental aging in combination with the superior mechanical characteristics (i.e., higher tensile strength, flexibility and enhanced longevity) when the epoxy modification is implemented in bitumen promises a very effective technology for developing long-lasting pavement materials.

Martin van de Ven

Papers

Effect of laboratory aging on chemistry and rheology of crumb rubber modified bitumen

Fatigue performance of long-term aged crumb rubber modified bitumen containing warm-mix additives

Chemical and Rheological Evaluation of Aged Lignin-Modified Bitumen

Evaluation of epoxy modification in asphalt mastic

Chemical and Oxidative Controlled Hardening of Epoxy-Modified Bitumen