Search results for "asphalt mixture"

Image analysis for detecting aggregate gradation in asphalt mixture from planar images

2012

Abstract The mechanical properties of bituminous mixture strongly depend on the gradation of the aggregate that represents the mineral skeleton of the mixture, since for open and gap-graded mixtures, stresses due to vehicles in movement on the pavement are mainly transmitted through their contacts. Internal structure of bituminous mixture is, therefore, of great interest for road and infrastructure engineering and it is appropriate to study it with recently developed image analysis method. The purpose of this study was to finalize an effective analysis of asphalt section image for automatically extracting aggregate gradation without the need of separation of the bitumen from the aggregate. …

ENVIRONMENTAL IMPACT OF BIO-BASED ASPHALT MIXTURES: LIFE CYCLE INVENTORY, LIFE CYCLE ASSESSMENT AND RECOMMENDATIONS

Linear and nonlinear fractional hereditary constitutive laws of asphalt mixtures

2016

The aim of this paper is to propose a fractional viscoelastic and viscoplastic model of asphalt mixtures using experimental data of several tests such as creep and creep recovery performed at different temperatures and at different stress levels. From a best fitting procedure it is shown that both the creep one and recovery curve follow a power law model. It is shown that the suitable model for asphalt mixtures is a dashpot and a fractional element arranged in series. The proposed model is also available outside of the linear domain but in this case the parameters of the model depend on the stress level.

Optimisation of liquid rubber modified bitumen for road pavements and roofing applications

2020

Abstract Polymer Modified Bitumens (PMBs) are largely used for pavement and roofing membranes applications with Styrene-Butadiene-Styrene Block copolymer (SBS) playing a major role in both markets despite its constantly increasing price due to the rising demand for quality bitumen modifiers. On the other hand, there is an increasing trend of recycling end of life tyres generating Recycled Tyre Rubber (RTR) at affordable price. This investigation aims at engineering a modified bitumen with a combination of Liquid Rubber (LR), a homogeneous blend of 50–70% RTR pre-processed in combination with heavy oils, and a wax denominated Ethylene Bis Stearamide (EBS). In the first phase, the effect of L…

Integrating Circularity in the Sustainability Assessment of Asphalt Mixtures

2020

Rising concerns about the impacts that the road engineering industry is imposing to the environment have redirected national road authorities to firmly re-consider the sustainability implications of their operations. Lately, though, sustainability has established a forceful correlation with the Circular Economy and its principles. The road engineering industry, therefore, is moving towards more circular approaches. However, this is occurring without the assessment of the potential impacts of such a transition. For this reason, in this study, a composite indicator, namely, Environmental Sustainability and Circularity indicator (ESCi), for investigating the potential effects that increased ci…

Mechanical and environmental performance comparisons of improved asphalt pavement wearing courses with high quality aggregates, steel slags, and poly…

2023

The use of waste materials in the construction of hot mix asphalt (HMA) pavements is an important opportunity for environmental sustainability. When properly designed, the alternative mixtures may also guarantee excellent mechanical performance. In this study, the results of an experimental analysis carried out on dense-graded HMAs are presented. In particular, the performance of a "traditional" surface mixture with limestone aggregate (designed with neat bitumen or a polymer-modified bitumen within the typical acceptance requirements for intended use in wearing courses) was compared with two alternative mixtures. The research investigated a surface mixture including coarse basaltic aggrega…

Application of textile fibres from tire recycling in asphalt mixtures

2022

The tire rubber obtained from end-of-life car and truck tires has been successfully recycled, among other applications, in the asphalt industry by providing a mean to get asphalt mixtures with superior performance. Textile fibres are another component derived from tire recycling typically disposed of in landfills or used in energetic valorisation. This paper wants to re-ignite interest in this secondary product by evaluating its use as a valuable resource in asphalt mixtures. Indirect tensile tests, dynamic modulus, fatigue resistance, and permanent deformation tests were performed on a series of AC14 asphalt mixtures manufactured with two binders, namely 50/70 and 35/50 pen, using several …

Performance-based characterization of recycled polymer modified asphalt mixture

2021

Due to the introduction of secondary materials, the asphalt mixtures to be designed and tested in our laboratories are constantly becoming much more complex than traditional asphalt mixtures making difficult to use conventional laboratory procedure and/or predict expected results. This study proposes a comprehensive characterization of asphalt mixture modified with recycled polymer compound by using both wet and dry process proposing adjustments to laboratory mixing and sample compaction procedure. Accordingly, three AC20 Hot Asphalt Mixture (HMA) were designed and their conventional and performance related properties were assessed by looking at a) Indirect Tensile test (ITS) a) moisture da…

Increasing the Circularity of asphalt mixtures: Integrated Sustainability and Circularity Assessment as a progress monitoring tool towards more Circu…

2021

Sustainability and Circular Economy (CE) are two concepts that lately have been profoundly linked to each other. The road engineering industry has gradually been adapting practices that are considered both circular and sustainable. However, not all of these practices entirely consider the whole life environmental and circularity assessment and implications of asphalt mixtures.; which in turn leads to doubtfully circular and sustainable approaches. For this reason in this thesis, after analysing the ways that National Road Authorities implement and communicate CE through questionnaires and web searches, a Material Circularity Index quantifying framework, based on the proposed methodology of …

Investigating the Multi-Recyclability of Recycled Plastic-Modified Asphalt Mixtures

2023

Although the benefits of asphalt recycling have been scientifically proven and several best practices are being implemented, further research is required in specific and specialized areas. One of these circumstances is the recycling of Reclaimed Asphalt Pavements (RAPs) that contain asphalt modifiers such as elastomers and/or plastomers. Following the principles of the circular economy and considering the sustainability implications of asphalt mixtures, this paper deals with the multi-recyclability of asphalt mixtures containing 50% RAP with and without a recycled plastic asphalt modifier and rejuvenating agent. The recycled plastic asphalt modifier was made of hard recycled plastics and wa…