•Effect of ageing and RAP content in the healing capacity of asphalt mix was assessed.•Both factors reduce effectiveness and energy efficiency of induction healing.•Both factors reduce density and ...increase the air voids content in compacted mixes.•Healing of mixes with high compaction level is worse.•Correlations between ageing days and RAP content were found.
Over the service life of asphalt roads, different factors produce, in the bitumen, a hardening process known as “ageing”. Also, the addition of recycled, aged material (i.e. RAP) to new mixes modifies the viscosity of the mix. The present research studies how these two actions affect the capacity for healing, by electromagnetic induction, of asphalt mixes. Mixes subjected to different ageing processes or containing different amounts of RAP were tested. Results show that both ageing, and RAP content contribute to increasing binder stiffness and air voids content in the mix. Therefore, the healing process becomes less effective and energy efficient.
Rap2B GTPase, a member of Ras-related protein superfamily, was first discovered from a platelet cDNA library in the early 1990s. Since then, it has been reported to play an important role in ...regulating cellular processes including cytoskeletal organization, cell growth, and proliferation. It can be stimulated and suppressed by a wide range of external and internal inducers, circulating between GTP-bound active state and GDP-bound inactive state. Increasing focus on Ras signaling pathway reveals critical effects of Rap2B on tumorigenesis. In particular, Rap2B behaves in a p53-dependent manner in regulation of apoptosis and migration. Apart from being an oncogenic activator, Rap2B has been found to participate in many other physiological events via diverse downstream effectors. In this review, we present recent studies on the structure, regulation, and multiple biological functions of Rap2B, shedding light on its potential status in treatment of cancer as well as other diseases.
Recently the waste of asphalt pavement materials has been increasing in day-to-day life by cost and economic criteria in the Indian environment. In this regard, the use of recycled asphalt pavement ...has grown worldwide reducing the use of virgin materials. Besides, the scarcity of natural aggregates, as well as the lack of eco-friendly materials, lead to an increase in the utilization of Reclaimed Asphalt Pavement (RAP) as an alternative material in road construction. This paper provides a comprehensive and insightful evaluation of the utilization of RAP aggregates based on characterization, strength, durability, and micro-structure properties along with life cycle analysis (LCA). For this purpose, a sequential characterization of the RAP materials is employed for a detailed analysis using physical and mechanical properties. Further, RAP aggregates' fresh and hardened properties, including durability properties, have been presented to show the potential utility as a partial substitute for natural aggregates (NA). Thus, the main objective of this critical review is to develop an extensive understanding of the present scenario in the utilization of RAP materials and identify the different properties needed for sustainability in pavement structures. Consequently, the various research gaps are highlighted based on the material properties, strength parameters, and circular economy of environmental impacts. Moreover, the optimum proportions of these substitute materials have been recommended for sustainable rigid pavement systems. The literature showed that the effect of RAP aggregates in concrete leads to loss of mechanical properties, which can be compensated by using various mineral admixtures or stabilizers to improve their strength and durability performance. Hence, this in-depth review will help the researchers, pavement engineers, and authorities of national and state highways with the effective use of RAP aggregates in rigid pavement construction.
•RAP aggregates are efficient and have greater potential to be used as substitute in concrete pavements.•The performance of RAP could reach the benchmark within 50% RAP replacement levels.•Durability properties of concrete are improved by addition of RAP content.•Industrial by-products have the potential to enhance pavement structures.•Life cycle analysis gives the feasible solution for cost and material management.
•Half-warm mix asphalt with 100% reclaimed asphalt pavement (HWMRA) was analyzed.•A lignin-rich byproduct was used as substitute for asphalt emulsions.•Substitution percentages of 0% (control ...mixture), 5%, 10%, 15% and 20% were employed.•The optimum percentage of substitution was 5%, resulting in an enhanced HWMRA.•This research promotes the circular economy and sustainable pavement construction.
To promote a circular economy and sustainable development, the possibility of using a lignin-rich industrial byproduct as a partial substitute for asphalt emulsions in road pavements is analysed. A half-warm mix reclaimed asphalt (HWMRA)-type AC 16 surf S, manufactured with 100% reclaimed asphalt pavement, is selected. Substitution percentages of 0% (control mixture), 5%, 10%, 15%, and 20% are employed.
The microstructure of the blend of the byproduct and asphalt emulsion is observed using scanning electron microscopy. The water resistance of the mixture is investigated using indirect tensile tests, as well as its volumetric properties. The stiffness, thermal susceptibility by indirect tensile tests, and resistance to permanent deformation by confined uniaxial compression tests and Hamburg wheel tracking tests are also studied.
The optimum percentage of byproduct substitution is 5%, resulting in an enhanced HWMRA with a slightly better water resistance, higher resistance to permanent deformation at low and medium environmental temperatures, and higher indirect tensile strength and stiffness than those of the control mix.
The agglomeration of reclaimed asphalt pavements (RAP) affects the low-temperature performance and water stability of hot-recycled asphalt mixtures (HAM). To address this problem, a surface-active ...regeneration agent which named polyacrylamide (PAM) was employed. The effects of the coarse-grained RAP agglomeration rate, the alterations in the aged asphalt before and after the addition of PAM, and the degree of diffusion and fusion between old and new asphalt on HAM performance were investigated using macroscopic experiments, molecular dynamics simulations, Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The findings revealed that the water stability of HAM first decreased and then slightly increased as the RAP agglomeration rate increased. Notably, at a 60% coarse-grained RAP agglomeration rate, the water stability of the mixture was at its poorest, accompanied by a declining low-temperature stability. Utilizing Fick's diffusion principle, in conjunction with molecular dynamics simulations, FTIR, and SEM analyses, it was observed that PAM effectively diffused and fused with the aged asphalt. This resulted in enhanced diffusion coefficients for both old and new asphalt, consequently mitigating aging effects on the aged asphalt. Furthermore, the regeneration agent facilitated the diffusion and fusion process between old and new asphalt, thereby improving HAM performance and reducing the adverse impact of coarse-grained RAP agglomeration on the road performance of thermally recycled mixtures.
•The agglomeration of recycle asphalt pavement material was characterized.•Molecular dynamics simulation was applied.•Analysis of the diffusion fusion characteristics of new and aged asphalt based on the Fick's diffusion principles•The effects of regeneration agent on enhancing the road performance of hot recycled asphalt mixtures was studied.
•A total of 600,000 wheel passes was conducted on three indoor test pavements.•Rutting and strain characteristics of three pavements were thoroughly analyzed.•Correlations between rutting depth and ...maximum underlayer strain were investigated.•Semi-flexible pavement presented the highest pavement condition index.•Semi-flexible mixture showed great potential as future airfield pavement material.
This study aimed to investigate the rutting and strain characteristics of flexible, semi-flexible (SF) and rigid pavement under the same accelerated loading condition. Specifically, flexible pavement was rubberized asphalt rejuvenated reclaimed asphalt pavement (RAP) pavement (RARR), semi-flexible pavement consisted of Styrene-Butadiene-Styrene modified porous asphalt concrete (SBS-PAC) and cement-based modified grouting material, while rigid pavement was polyurethane (PU) mixtures. An indoor test field was constructed and accelerated pavement tester (APT) was employed to apply continuous wheel loads. Twelve embedded fiber grating strain sensors were placed at the bottom of the surface layer with four in under each type of pavement. In total, 600,000 wheel passes were applied. Results revealed that no rutting hump was discovered for RARR while it was not until the completion of 150,000 wheel passes that PU and SF pavement saw evident rutting humps. As total rutting depth and rutting area increased, the fact that hump depth ratio decreased while hump area ratio increased indicated that rutting humps tended to spread outwards. When it came to maximum micro-strain underneath the pavement layer, it was found that with increasing number of accumulated wheel passes, RARR pavement presented the largest transverse micro-strain while SF pavement presented the largest longitudinal strain. Correlation analyses indicated that maximum micro-strain was in good exponential correlation with maximum rutting depth for RARR, SF and PU pavement. Finally, SF pavement presented the best PCI among the three pavements while PU pavement presented the worst, mainly because of its poor rutting resistance.
The application of reclaimed asphalt pavement (RAP) materials has become an important subject of sustainable development in the field of road construction. In addition, the low carbon asphalt ...technology (i.e. warm mix technology) is recently employed to reduce the energy consumption and emission in RAP application. Generally, during the RAP mixing process, softer asphalt or rejuvenator is typically used to offset the aged effect of RAP materials. Therefore, further investigation on blending efficiency of virgin and aged asphalts in terms of warm mix technology and its influence factors has become extremely important to save the energy and reduce the emission. In this study, Fourier Transform Infrared Spectroscopy was used to evaluate the blending degree of virgin and aged asphalts involved warm mix additive. Additionally, some factors such as blending time, blending temperature, and RAP content on the blending efficiency were investigated in the study. The research results indicated that all these factors had individual or combined effects on the blending degree of recycled asphalt mixtures. Furthermore, the energy consumption of mixing process was measured based on a laboratory study. It was found that an extended blending duration had a better energy effectiveness on increasing the blending degree within the first 3-min. After that, the blending degree could be improved efficiently with less energy consumption by increasing the blending temperature. In addition, utilizing warm mix additive could also significantly promote blending efficiency.
What did rap music and hip hop culture inherit from the spirituals, classic blues, ragtime, classic jazz, and bebop? What did rap music and hip hop culture inherit from the Black Women’s Club ...Movement, New Negro Movement, Harlem Renaissance, Hipster Movement, and Black Muslim Movement? How did black popular music and black popular culture between 1900 and the 1950s influence white youth culture, especially the Lost Generation and the Beat Generation, in ways that mirror rap music and hip hop culture’s influence on contemporary white youth music, culture, and politics? In Hip Hop’s Amnesia award-winning author, spoken-word artist, and multi-instrumentalist Reiland Rabaka answers these questions by rescuing and reclaiming the often-overlooked early twentieth century origins and evolution of rap music and hip hop culture. Hip Hop’s Amnesia is a study about aesthetics and politics, music and social movements, as well as the ways in which African Americans’ unique history and culture has consistently led them to create musics that have served as the soundtracks for their socio-political aspirations and frustrations, their socio-political organizations and nationally-networked movements. The musics of the major African American social and political movements of the 1950s, 1960s, and 1970s were based and ultimately built on earlier forms of “African American movement music.” Therefore, in order to really and truly understand rap music and hip hop culture we must critically examine both classical African American musics and the classical African American movements that these musics served as soundtracks for. This book is primarily preoccupied with the ways in which post-enslavement black popular music and black popular culture frequently served as a soundtrack for and reflected the grassroots politics of post-enslavement African American social and political movements. Where many Hip Hop Studies scholars have made clever allusions to the ways that rap music and hip hop culture are connected to and seem to innovatively evolve earlier forms of black popular music and black popular culture, Hip Hop’s Amnesia moves beyond anecdotes and witty allusions and earnestly endeavors a full-fledged critical examination and archive-informed re-evaluation of “hip hop’s inheritance” from the major African American musics and movements of the first half of the twentieth century: classic blues, ragtime, classic jazz, swing, bebop, the Black Women’s Club Movement, the New Negro Movement, the Harlem Renaissance, the Bebop Movement, the Hipster Movement, and the Black Muslim Movement.
Cell-matrix adhesion strongly influences developmental signaling. Resulting impacts on cell migration and tissue morphogenesis are well characterized. However, the in vivo impact of adhesion on fate ...induction remains ambiguous. Here, we employ the invertebrate chordate Ciona intestinalis to delineate an essential in vivo role for matrix adhesion in heart progenitor induction. In Ciona pre-cardiac founder cells, invasion of the underlying epidermis promotes localized induction of the heart progenitor lineage. We found that these epidermal invasions are associated with matrix adhesion along the pre-cardiac cell/epidermal boundary. Through targeted manipulations of RAP GTPase activity, we were able to manipulate pre-cardiac cell-matrix adhesion. Targeted disruption of pre-cardiac cell-matrix adhesion blocked heart progenitor induction. Conversely, increased matrix adhesion generated expanded induction. We were also able to selectively restore cell-matrix adhesion and heart progenitor induction through targeted expression of Ci-Integrin β2. These results indicate that matrix adhesion functions as a necessary and sufficient extrinsic cue for regional heart progenitor induction. Furthermore, time-lapse imaging suggests that cytokinesis acts as an intrinsic temporal regulator of heart progenitor adhesion and induction. Our findings highlight a potentially conserved role for matrix adhesion in early steps of vertebrate heart progenitor specification.
•Promotes the usage of recycled asphalt pavement (RAP) and fly ash in base courses.•Alkali activation of fly ash increased the reactivity, thus, the strength of mortar.•Permanency of the base course ...mixes are studied by durability and leachate tests.•Strength of mixes continue to increase up to 224 days, though, marginal after 56 days.•No detrimental affects are noticed due to aged bitumen coat on RAP aggregates.
Utilization of reclaimed asphalt pavement (RAP) materials in pavement base courses has proven to be a viable alternative not only to conserve the natural resources but also to reduce the environmental pollution and landfilling. Recent studies demonstrated that untreated RAP is inefficient to be used as a pavement material unless blended with virgin aggregates (VA) and/or stabilized with additives, because of their inferior gradation and bonding characteristics. Most of the design guidelines limit the amount of RAP in the base course up to 30% by weight of the virgin aggregates, in lieu of the aged bitumen coating present on the RAP aggregates and lack of understanding of the long term performance of the material. Hence, in this study it is proposed to promote a high percentage of RAP in the base course by stabilizing the RAP:VA mixes with a fly ash. However, the presence of the aged bitumen over the RAP aggregates may affect the long term strength and durability of the design mixes. Hence, to attain the desired design strength, the fly ash is activated in an alkali environment to form a geopolymer by triggering the unreacted polymeric compounds present in the fly ash. However, exposure of these mixes to the severe moisture and temperature variations may alter the cementation. This process may lead to strippage of the asphalt coating from the RAP aggregates and leach out the stabilizer from the mixes. Hence, the present study verifies the suitability of these mixes in terms of their initial compressive strength and the corresponding retained strength after exposure to the alternate wet/dry cycles in the severe laboratory environment. The permanency of the stabilizer/activator is also verified through leachate studies. Variation in the hydration products and oxide contents of the mixes are verified at every stage using X-ray diffraction (XRD) and X-ray florescence (XRF) studies. The comprehensive test results indicated that the strength loss of RAP:VA mixes is very minimal and are found suitable for the base course applications.
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