Quality-control procedure for dry-process rubberised asphalt mastics

Astolfi, Armando; Subhy, Ayad; Praticò, Filippo Giammaria; Lopresti, Daniel

doi:10.1201/9781351063265-75

Cited by 5 publications

(4 citation statements)

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“…When working with chemically activated crumb rubber, as here, swelling will be much faster hence the material will reach a state at which it can be paved quicker. This is evidenced in the viscosity measurements over time performed previously [6]. The rubber amount was based on ca.…”

Section: Methodsmentioning

confidence: 70%

“…The rubber amount was based on ca. 15% of fresh bitumen as shown by previous experiments [6]. Due to the potential ageing effects on the mixture induced by this stage, and to allow proper comparison between the mixtures, the reference mixtures were subjected to the rest period at high temperature (digestion process) as well.…”

Section: Methodsmentioning

confidence: 99%

“…The nature of this interaction is a combination of physical and chemical as reported in a review by Lo Presti [5] comprising partial digestion of the rubber into the bitumen on the one hand and, on the other, adsorption of the aromatic oils within the polymeric chains that are the main components of the rubber. Latest versions of modified CR have reduced this time to 30 min or lower, which could easily coincide with the hauling distance from the plants to the construction site [6].…”

Section: Introductionmentioning

confidence: 99%

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Functional and environmental performance of plant-produced crumb rubber asphalt mixtures using the dry process

et al. 2021

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Incorporating crumb rubber (CR) using the dry process, directly in the asphalt mixture rather than into the bituminous binder requires no plant retrofitting, and therefore is the most practical industrial method for CR incorporation into asphalt mixtures. Nevertheless, very few large scale studies have been conducted. This work uses a holistic approach and reports on the functional and environmental performance of asphalt mixtures with different concentrations of CR fabricated employing the dry process in asphalt plants. Gaseous emissions were monitored during the production and laboratory leaching tests simulating the release of pollutants during rain, was conducted to evaluate the toxicology of both the CR material alone and the modified asphalt mixtures. In addition, laboratory compacted samples were tested to assess their fatigue behavior. Furthermore, noise relevant surface properties of large roller compacted slabs were evaluated before and after being subjected to a load simulator (MMLS3) to evaluate their resistance to permanent deformation. The results confirm that comparable performance can be achieved with the incorporation of CR using the dry process for high performance surfaces such as semi-dense asphalt, which usually require the use of polymer modified binders. Environmental performance improvement can be achieved by a washing step of the CR material that could remove polar CR additives which have commonly been used as vulcanization accelerator during rubber production.

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Section: Methodsmentioning

confidence: 70%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Functional and environmental performance of plant-produced crumb rubber asphalt mixtures using the dry process

et al. 2021

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“…They have a pumping effect that helps maintain particles in suspension and confer a high shear deformation, improving the homogeneity of the system. On that basis, DHR impellers have been successfully developed for measuring the viscosity of crumb rubber modified binders and mastics (Astolfi et al, 2019;Medina et al, 2020). DHR allowed continuous measurement of viscosity guaranteeing the stability of the sample.…”

Section: Review On Viscosity Measurement Of Cold Bitumen Emulsion Slu...mentioning

confidence: 99%

Rheological characterisation of cold bitumen emulsion slurries

Mignini

Presti

Airey

et al. 2021

Road Materials and Pavement Design

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Rheological characterisation of cold bitumen emulsion slurriesThe performance of cold bitumen emulsion (CBE) mixtures is strongly linked to an optimised design of the binder blends and mastics. Hence type and dosages of bitumen, mineral additions but also their workability and compactability are key features to be characterised and optimised. This study aims at providing the scientific community with an approach for the fundamental characterisation of CBE materials by means of rotational viscometry. At first, a procedure for measuring the viscosity of CBE slurries using the Brookfield viscometer was investigated by comparing viscosity results obtained by using a traditional spindle geometry and a novel impeller engineered to avoid phase separation during testing: the dual helical ribbon. Afterwards, the effect of different types of mineral additions and bitumen emulsion was measured and modelled, as well as the influence of the overall solids concentration, to get useful information towards optimised design of CBE mixtures. The Krieger-Dougherty model proved to be a powerful tool to fit results and provide fundamental parameters for an improved engineering characterisation of CBE materials. Overall, the dual helical ribbon impeller was demonstrated to be a promising tool for the fundamental rheological characterisation of cold bitumen emulsion slurries.

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