1,720,967 research outputs found
Effects of different aging methods on chemical and rheological properties of bitumen
No full textBitumen undergoes ageing, which leads to changes in its chemical and rheological properties, causing it to become harder and more brittle with time. This study aims to compare the effects of different laboratory ageing methods on the chemistry and rheology of three bitumen types: a Pen 40=60, a Pen 70=100, and a polymer-modified bitumen (PmB). Four ageing protocols were applied: ageing at room temperature, oven ageing, pressure ageing vessel (PAV), and rolling thin-film oven test (RTFOT) combined with PAVageing. The effects of temperature, pressure, and ageing time were studied using dynamic shear tests and infrared spectroscopy. The results highlight the relationship between chemistry and rheology of bitumen. Bitumen hardening, which was revealed by an increase in complex modulus and a decrease in phase angle, was reflected in the growth of specific chemical functional groups. Among all materials, soft bitumen showed the greater tendency to oxidize. Different behavior was observed for PmB, which presented the highest resistance against oxidation among the studied bitumens, even though the reaction with oxygen caused the deterioration of the added polymer modifiers.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Pavement Engineerin
Towards more sustainable infrastructures through circular processes: Environmental performance assessment of a case study pavement with recycled asphalt in a life cycle perspective
No full textPromotion of technological and ecological transition through innovations on paving materials and their production leads to more sustainable roads. Highly recycled Hot Mix Asphalt (HMA) mixtures containing Reclaimed Asphalt Pavement (RAP) were considered to produce eco-friendly materials for highways’ base and binder layers. The asphalt plant type is a key factor to increase RAP recycling rate in HMA mixes. A traditional (30% RAP) and a novel (70% RAP) batch plants were considered, with different initial investments and maintenance costs. The environmental and economic impacts of HMAs production in the chosen plants were compared, as a decisionmaking tool for innovation and plant investments in asphalt industry. The investigated scenarios were: 1 ton of HMA and 1 km of one-way highway considering construction/maintenance processes over 20-year; which modelled RAP as either an internal or an end-of-waste source of a company. The results highlighted positive effects of using higher RAP content in a novel asphalt plant reducing the CO2,eq emissions during the production cycle from -28% up to -39% approx. depending on the model, and during the entire service life of the pavement (negligible and - 13% approx.). From economic viewpoint, increasing the RAP quantity a decreasing of HMA total cost was experienced, but additional related cost on transport and RAP recycling should be considered for a comprehensive evaluation of the proposed solution
Effect of filler properties on the hydrothermal ageing of bituminous mastics
Full text linkMoisture sorption can significantly influence hydrothermal ageing and alter the chemical and rheological properties of bituminous mastics. Mineral filler particles are added to bituminous binders to form mastics with increased stiffness. The addition of fillers can considerably change the moisture sorption and the physico-chemical properties of binders by surface interactions and physical presence. This study aims to investigate the effect of filler type on the moisture-induced changes of bituminous mastics after wetting-drying cycles by means of sorption, rheological and infrared spectrometry tests. The results show that mineral fillers with higher diffusivity increase the overall capacity of mastics to absorb moisture, but at the same time allow for moisture desorption during drying. Nevertheless, it has been found that it is not the diffusivity properties but rather the bitumen and filler interactions that control the hydrothermal ageing of the mastics.Pavement Engineerin
Recycling shredded waste cigarette butts as stabilising fibres in stone mastic asphalt concretes
Full text linkConsidering the global burden of cigarette consumption, the disposal of cigarette butts has become an
inevitable issue. Compared to traditional disposal methods, such as landfilling or incinerating, the
recycling of these wastes is clearly an eco-friendlier solution. In this research, waste electronic
cigarette butts (E-CBs) were collected and recycled in bituminous mixtures, aiming to increase the use
of sustainable road construction materials. The objective of this research is to explore the possibility of
using waste E-CBs as an alternative stabilising fibre in asphalt mixtures. To this end, shredded waste ECBs
were incorporated in Stone Mastic Asphalt (SMA) and compared with the conventional cellulose
fibres. Furthermore, to investigate the effects of powders (below 0.063 mm) from the waste E-CBs on
the rheological properties of bitumen, tests were conducted on base SBS-modified bitumen and its
mastics. Results show that the waste powder was unfavourable to the thermal susceptibility of the
resulting binder. SMA samples with shredded E-CBs were also characterised through physical and
mechanical tests and compared to the reference mixture using cellulose fibres. It was concluded that
using waste E-CBs in SMA can be considered a promising alternative for replacing cellulose fibres and
avoiding the disposal of cigarette butts
Waste Silt as Filler in Hot Mix Asphalt: A Laboratory Characterization
Full text linkSeveral studies aimed to improve both the performance and environmental impact of asphalt pavements using waste and recycled materials as fillers. This study focused on the effect of untreated and thermally treated silt as a filler in hot mix asphalt (HMA). The silt used in the study was a byproduct from a local aggregate production plant in Bologna, Italy. Mineral and chemical analyses revealed that the waste silt required thermal treatment at 750 °C for 2 h. The study compared the use of calcined silt, untreated silt, and a common limestone filler in the production of asphalt mastics and HMA specimens. The rheological properties of the mastics were analyzed using frequency sweep and multiple stress creep recovery tests. The physical and mechanical characteristics of the HMAs were evaluated through the air voids content, Marshall stability and indirect tensile strength tests. Additionally, the water susceptibility and thermal sensitivity of the HMAs were evaluated through the indirect tensile strength ratio and indirect tensile stiffness modulus at different testing temperatures. The results showed that the addition of calcined silt had no significant effect on the rheological properties of the mastic or the optimal binder content. However, the samples produced with thermally treated silt showed the highest stiffness and resistance to rutting compared with the other samples. On the other hand, the addition of untreated silt slightly decreased the stiffness value of the samples. In conclusion, the use of waste silt as a filler has potential as a sustainable and eco-friendly solution for HMAs
Performance Evaluation of Stone Mastic Asphalt Reinforced with Shredded Waste E-cigarette Butts
Full text linkThe recycling of waste materials in asphalt pavements is pivotal for advancing the road industry,
offering numerous environmental, economic, and societal benefits. This study explores the
recycling potential of waste electronic cigarette butts (E-CBs) within stone mastic asphalt (SMA)
mixtures, serving as a substitute for cellulose fibres and enhancing mechanical performance.
Considering the critical role of fibre size in asphalt mixtures, two different E-CB shredding sizes
(10 and 15 mm) were selected for examination. Additionally, the influence of the plastic
component within E-CBs was investigated. The stabilizing effects of using the shredded E-CBs
were evaluated via drain-down tests, followed by a series of standard laboratory tests aimed at
assessing physical and mechanical properties. Results demonstrate acceptable drain-down properties,
volumetric properties, and moisture susceptibility for the use of all four shredded E-CBs.
Among the four mixtures incorporating the waste fibres, the utilization of 15 mm shredded E-CBs
without plastic constituents yielded the highest values for indirect tensile strength (ITS) and indirect
tensile stiffness modulus (ITSM), coupled with excellent water susceptibility and rutting
performance. It can be considered a promising alternative to the traditional cellulose fibre. Larger
shredded E-CBs exhibited potential for improving mechanical properties, encompassing cohesion,
stiffness modulus, and rutting resistance. Although plastic inclusion can enhance rutting resistance,
the higher thermal susceptibility associated with plastic warrants careful consideration.
Future research may focus on investigating the fatigue and low-temperature cracking properties,
as well as the reinforcing mechanisms of shredded E-CBs in asphalt mixtures using microcharacterization
techniques
Mechanical Characterization of Thin Asphalt Overlay Mixtures with 100% Recycled Aggregates
Full text linkAsphalt pavements inevitably deteriorate over time, requiring frequent maintenance work to ensure the proper serviceability of the road network. Small interventions, such as resurfacing for pavement preservation, are preferable to reconstruction at the end of roads’ in-service lives as they limit environmental- and economic-related impacts. Thin asphalt overlay (TAO) mixture represents a suitable maintenance solution to restore the functional properties of road surfaces. Due to the increasing awareness of the depletion of non-renewable resources and the importance of promoting the circular economy, this study evaluated the possibility of using fully recycled TAO mixes by investigating their volumetric and mechanical properties. Two eco-friendly TAO mixes were designed using recycled aggregates from reclaimed asphalt pavements, a municipal solid waste incinerator, and steel slags in order to meet EN 13108-2 requirements. The TAO mixes differed in regard to the type of bituminous binder (neat/SBS-modified bitumens) and fibres (natural/synthetic) employed. The preliminary results demonstrated that the presence of recycled aggregates did not negatively affect the workability and the mechanical performances of the two sustainable mixtures in terms of stiffness, tensile resistance, rutting and moisture susceptibility. Of these, the TAO mix with neat bitumen and synthetic fibres showed enhanced mechanical performance highlighting the structural effects of the used fibres
Use of bio-based products towards more sustainable road paving binders: A state-of-the-art review
Full text linkMany industrial sectors exploit fossil sources to develop useful and necessary materials for our needs, such as bituminous paving materials. Bitumen, a key component of asphalt mixtures, is derived from oil refining and its properties are influenced by the crude oil source and refining process, resulting in a significant carbon footprint. With growing awareness of resource depletion and environmental concerns, pavement researchers are exploring sustainable alternatives to reduce dependence on fossil sources. This includes a rising trend in using renewable materials like biomasses to produce bio-based binders as substitutes for bitumen, aiming for a more sustainable approach. Biomasses, including vegetal and animal wastes, and waste cooking oils, as substitutes for crude oil in the production of bio-binders. Through thermochemical conversion (TCC), such as pyrolysis, biomasses can be converted into bio-char and bio-oils, which can replace fossil-based components in binders. Researchers have utilized these bio-products to reduce the dependency on fossil fuels in binders. However, there are no set minimum requirements for bio-components in bio-based binders. As the percentage of replaced bitumen increases, various types of binders are produced, including modified bitumen, extended bitumen, and alternative binders, where the fossil replacement is gradual. Overall rheological tests on bio-binders, reveal that those containing bio-char exhibit increased viscosity, stiffness, rutting resistance, and sometimes antioxidant properties. Conversely, bio-binders with bio-oils as bitumen substitutes show poorer performance at high temperatures but improved behavior at low temperatures. These results suggest that bio-binders could provide versatile solutions for various climatic and loading conditions in road construction. However, the development of pavement mixtures based on bio-binders has not been studied in depth and requires further attention to unlock its full potential. As sustainability considerations, including life cycle assessments (LCA) and life cycle cost analyses (LCC), are crucial aspects for future studies. It is essential not only to collect data on the performance characteristics of bio-binders but also to understand their environmental impact and recyclability. In-depth evaluations using methods such as LCA and LCC will provide valuable insights into the overall sustainability and long-term viability of these products
Assessment of high-enthalpy composite eutectic phase change materials efficiency in asphalt binders for cooling pavements
Full text linkPhase change materials (PCMs) as thermal energy storage solutions can mitigate pavement damage and alleviate
the urban heat island effect. A stable shape, suitable melting temperature, and high-enthalpy can extend the
application potential of PCMs in cooling pavements. The goal behind this study is to investigate the potential use
of two high-enthalpy composite phase change materials (CPCMs) in an SBS-modified asphalt binder through
thermal and chemo-rheological tests. Herein, using a ternary eutectic mixture with adipic/sebacic/stearic acids
(named A) and a binary eutectic mixture consisting of stearic/palmitic acids (named B) as two distinct PCMs and
expanded graphite as supporting material, two novel CPCMs were successfully prepared through vacuum
impregnation. The findings showed that the encapsulation efficiency of both CPCM-A and CPCM-B exceeded
90%. The melting enthalpy (Hm) and the melting phase-change temperatures (Tm) values were 193.3 J/g and
61.7 ◦C for CPCM-A, 189.6 J/g, and 50.5 ◦C for CPCM-B. The Hm of the two related asphalt binders that
incorporate the developed CPCMs (SBS-A and SBS-B) were 19.5 J/g and 17.2 J/g, respectively, indicating high
thermal storage and management capabilities. This allowed SBS-A and SBS-B to exhibit maximum temperature
differences of 13.1 ◦C and 10.7 ◦C, with temperature lags of 1500 s and 2610 s, respectively. Also, the CPCMs and
the related asphalt binders presented outstanding thermal and chemical stability. The CPCMs enhanced the
resistance to deformation and deformation recovery capability of asphalt at high temperatures and under severe
loads. However, SBS-B experienced an earlier phase transition than SBS-A, ultimately leading to a diminished
ability to withstand deformation at the testing temperature. To sum up, opting for CPCM-A over CPCM-B for
asphalt pavement cooling applications is advisable
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