New simplified approach for obtaining a reliable plateau value in fatigue analysis of bituminous materials

The Plateau Value (PV) based on the Ratio of Dissipated Energy Change (RDEC) approach has been proven to provide a unique relationship with the fatigue life, Nf, independent of loading mode, temperature and frequency. In this paper, a new simplified approach is proposed to compute the unique energy parameter PV. The results of this study show that applying the proposed method allows a unique fatigue power law to be produced and eliminates the ambiguity and variability in calculating PV. However, the study also shows that the PV-Nf fatigue curves for bituminous materials are dependent on material type which is contradictory to other studies dealing with PV. The study also highlights the importance of appropriately identifying the fatigue failure point prior to commencing any fatigue analysis

Manufacturing Terminal and Field Bitumen-Tyre Rubber Blends: The Importance of Processing Conditions

No-agitation Tyre Rubber Modified Bitumens (TR-MBs), also known as "terminal blends" or "field-blends", are quite new technologies leading to bituminous binders similar to polymer modified bitumens in terms of both rheology and needed efforts during paving operations. Their manufacturing, as well as other TR-MBs, is strongly dependent on the selected processing variables as well as on the chosen materials. This study presents a literature review to provide an overview of the TR-MB technologies which focuses on the influence of processing conditions on the modification process, storage stability and overall properties of the final bitumen - tyre rubber blends. (C) 2012 The Authors. Published by Elsevier Ltd. Selection and/or peer-review under responsibility of SIIV2012 Scientific Committe

Luca Ronconi e Rafael Spregelburd: la simultaneità attraverso La Modestia

Argomento della mia tesi di laurea è l’analisi dello spettacolo teatrale La Modestia, del drammaturgo argentino Rafael Spregelburd, per la regia di Luca Ronconi. Lo spettacolo assume particolare rilevanza sia per le tematiche sia per la struttura drammaturgica del testo, diversa dai canoni tradizionali del teatro e intesa a spiazzare letteralmente lo spettatore nella ricostruzione della trama. Il testo è composto da due storie, delle quali non vengono forniti gli elementi temporali e spaziali per la loro comprensione. Non solo. Esse si fondono, si legano e hanno continui richiami l’una sull’altra, lasciando che sia lo spettatore a crearsi un proprio ordine nella comprensione della storia. Inoltre l’attenzione per questo spettacolo, mossa non solo da ragioni puramente tematiche, come il ruolo (non) svolto dalla parola, incapace di offrire chiarezza allo spettatore, è stata stimolata dall’interesse per le capacità metodologiche del regista. Infatti si porrà l’attenzione su come un regista affermato e famoso, come Luca Ronconi, si pone di fronte un testo della drammaturgia contemporanea, interpretandone in particolar modo le ragioni per cui la scelta è ricaduta su tale testo, e sul modo di analizzarne gli elementi drammaturgici per la messinscena finale. Per tale motivo, l’analisi dello spettacolo sarà preceduta da una ricostruzione della carriera attoriale e registica di Luca Ronconi, per coglierne gli elementi più importanti, al fine di offrire un quadro generale su una delle figure più influenti e importanti del teatro contemporaneo, ma soprattutto per cercare dei collegamenti tra lo spettacolo da me analizzato e quelli della sua carriera. La ricerca da me svolta, oltre che essersi basata sul materiale presente in biblioteca di dipartimento e su alcune testimonianze da parte di attori che sono stati diretti da Luca Ronconi, si è avvalsa anche della consultazione diretta degli archivi di teatri nazionali come il Piccolo Teatro di Milano e il Teatro Metastasio di Prato, in particolare per quanto riguarda la consultazione della rassegna stampa locale e nazionale, sia per quanto riguarda La modestia sia per spettacoli andati in scena nei rispettivi teatri. Inoltre vi sarà un capitolo che tratterà la figura del pittore Hieronymus Bosch, con l’analisi di alcune sue opere, delle tematiche e dello stile da lui adottato, data l’enorme influenza che quest’ultimo ha avuto sul drammaturgo Spregelburd, al punto da inserirlo nella sua raccolta intitolata “Eptalogia di Hieronymus Bosch” e che prende spunto dalla sua tavola sui sette peccati capitali (I sette peccati capitali), che il drammaturgo argentino ha interpretato in chiave moderna. La modestia è una di questi, gli altri sono: La stravaganza, L’inappetenza, La cocciutaggine, Il panico, La paranoia e La stupidità. Sarà presente, oltre che una breve analisi di queste ultime opere, anche una biografia del suo autore, il drammaturgo Rafael Spregelburd. Seguirà l’analisi dello spettacolo, che ho avuto modo di vedere sia direttamente dal vivo al Teatro Verdi di Pisa sia in video, tramite l’archivio del Piccolo Teatro di Milano. Per quanto concerne la descrizione dello spettacolo, essa comprenderà l’analisi, scena per scena, dei suoi aspetti puramente tecnici come la scenografia, l’illuminotecnica e i costumi, sia gli aspetti che riguardano la semiotica dello spettacolo, come l’interpretazione dei personaggi da parte degli attori, e la relazione sia tra loro sia con gli elementi presenti in palcoscenico. Inoltre si analizzeranno anche le reazioni del pubblico, sia quelle degli spettatori presenti in sala sia quelle della critica giornalistica. Per concludere saranno presenti alcune testimonianze di attori che hanno lavorato negli spettacoli di Luca Ronconi, oltre che un’intervista da me compiuta a Ronconi stesso, dove ho avuto modo di fargli delle domande riguardanti sia l’approccio registico nei confronti del testo La modestia, sia alcune curiosità e opinioni riguardo alla sua concezione del teatro in generale

Recycled tyre rubber modified bitumens for road asphalt mixtures: a literature review

Nowadays, only a small percentage of waste tyres are being land-filled. The Recycled Tyre Rubber is being used in new tyres, in tyre-derived fuel, in civil engineering applications and products, in moulded rubber products, in agricultural uses, recreational and sports applications and in rubber modified asphalt applications. The benefits of using rubber modified asphalts are being more widely experienced and recognized, and the incorporation of tyres into asphalt is likely to increase. The technology with much different evidence of success demonstrated by roads built in the last 40 years is the rubberised asphalt mixture obtained through the so-called “wet process” which involves the utilisation of the Recycled Tyre Rubber Modified Bitumens (RTR-MBs). Since 1960s, asphalt mixtures produced with RTR-MBs have been used in different parts of the world as solutions for different quality problems and, despite some downsides, in the majority of the cases they have demonstrated to enhance performance of road’s pavement. This study reports the results of a literature review upon the existing technologies and specifications related to the production, handling and storage of RTR-MBs and on their current applications within road asphalt mixtures. Furthermore, considering that RTR-MBs technologies are still struggling to be fully adopted worldwide, mainly because of poor information, lack of training of personnel and stakeholders and rare support of local policies, the present work aims to be an up-to-date reference to clarify benefits and issues associated to this family of technologies and to finally provide suggestions for their wide-spread use

Quality control of manufacturing and hot storage of crumb rubber modified binders

The ultimate performance of crumb rubber modified (CRM) binders is linked to the accurate control of the properties during manufacturing and hot storage. However, due to their complexity, asphalt technologists find the characterisation of these materials still challenging. In this study, the adoption of a Dual Helical Ribbon (DHR), a novel mixing/measuring device for rotational viscometers, is proposed for the real-time monitoring of CRM binders during manufacturing and hot storage. According to the laboratory results, manufacturing periods of 45-60 min at 195 degrees, as well as storage temperatures not exceeding 150 degrees C, are recommended for this type of modified binders. (C) 2019 Elsevier Ltd. All rights reserved

Modelling the Environmental and Economic Life Cycle Performance of Maximizing Asphalt Recycling on Road Pavement Surfaces in Europe

The road pavement industry, worldwide, has often shown reluctance in quickly implementing innovative practices; however, in the case of raw material consumption, a cultural change is necessary and, in this sense, sustainability assessment could play a major role. Along these lines, this research study aims to provide evidence to all the involved stakeholders (material producers, pavement contractors, and road authorities) of how life cycle-based techniques can be crucial in evaluating whether the adoption of asphalt mixtures with high contents of reclaimed asphalt (RA) for wearing courses is actually a sustainable practice for major European roads. An evaluation framework composed of a life cycle assessment, to calculate the carbon footprint of both pavement materials and pavement activities, and a life cycle cost assessment, performed to determine the overall economic burden of the related road pavement surface courses and maintenance strategies over a sixty-year analysis period, is presented and applied to selected case studies. These were developed together with three major European national road authorities and include scenarios involving the construction of road surfaces with asphalt mixtures containing up to 90% RA. Results have shown that whenever high-content RA mixes do not under-perform against conventional mixtures, up to 50% CO2eq savings can be registered and up to 60% economic cost reductions can be reported. The durability of road pavement layers remains a key parameter for any road pavement sustainability assessment exercises; therefore, in order to adapt the obtained results to other contexts, researchers should always consider conducting a sensitivity analysis of the reference service life and/or road authorities should somehow request road pavement durability as a pre-requisite within procurement practices

Toward more realistic viscosity measurements of tyre rubber–bitumen blends

The measurement of rheological properties of the tyre rubber bitumen blends is often challenging due to presence of suspended tyre rubber’s crumbs. Furthermore, the phase separation during the course of measurements makes the viscosity of these non-homogeneous blends difficult to ascertain. In this study, a new dual helical impeller was designed and manufactured to be used with a rotational viscometer in order to have a real-time control of the viscosity while performing a laboratory mixing of the blends. Layer based manufacturing techniques showed to be a convenient method to produce complex shaped impeller prototypes before manufacturing the more expensive stainless steel assembly. Impeller geometry was optimised to create a convective like flow within the sample and so minimise phase separation. Shear rate constant is geometry dependent and a calibration exercise was carried out to ascertain this. Results of both calibration and validation phases showed that the new impeller provides reliable viscosity measurements of homogenous fluids such as neat bitumen. With regards to complex fluids the new impeller showed a more stable and realistic trend than that obtained by using a standard spindle. In fact, it was demonstrated that the new impeller significantly decreases phase separation within the blend and in turns provides a more realistic measurement of the viscosity. This system represents a feasible and improved solution for optimising the laboratory modification process of tyre rubber bitumen blends by adapting the rotational viscometer as a low-shear mixer

Toward the Development of Load Transfer Efficiency Evaluation of Rigid Pavements by a Rolling Wheel Deflectometer

The jointed rigid pavement is currently evaluated by the Falling weight deflectometer which is rather slow for the testing of the jointed pavements. Continuous nondestructive evaluation of rigid pavements with a rolling wheel deflectometer can be used to measure the load transfer and is investigated. Load transfer is an important indicator of the rigid pavement's condition and this is the primary factor which is studied. Continuous data from experimental measurements across a joint allows for the determination of not only the load transfer efficiency provided parameters characterizing the pavement is known. A three-dimensional semi-analytical model was implemented for simulating the pavement response near a joint and used for interpretation and verification of the experimental data. Results show that this development is promising for the use of a rolling wheel deflectometer for rapid evaluation of joints

An investigation on using pre-treated tyre rubber as a replacement of synthetic polymers for bitumen modification

Rubberized bitumen obtained through a swelling process, has widely proven to be a successful technology for asphalt pavement applications and a solution to reduce the dismantling of tyre rubber on landfills. However, this technology presents two main operative issues which needs the adoption of costly special equipment. Firstly, significant high value of High Temperature Viscosity (HTV) which imposes mixing and compaction difficulties and leads to increased energy consumption and emissions. Furthermore, during the hot storage period, phase separation between rubber particles and the base bitumen could occur. Developing Recycled Tyre Rubber Modified Bitumen (RTR-MBs) with improved storage stability and reduced values of HTV could allow using this technology in standard asphalt plants, resulting in an environmental-friendly and cost-effective option of standard Polymer Modified Bitumen (PMBs). In this study, two different pre-treated and one straight ambient recycled rubbers were used to produce RTR-MBs. The first RTR was pre-treated by special oil and Warm Mix Additives (WMA) and the second was partly devulcanised. Also, two base binders were selected with large differences in mechanical properties in order to identify the effect of base binder. The high temperature viscosity was successfully reduced by using pre-treated RTR. The use of RTR together with Fischer–Tropsch wax (Sasobit®) in bitumen technology offered superior high in-service temperature properties and reduced value of HTV, and thus can be preferred option over styrene–butadiene–styrene (SBS) modification

On the degree of binder activity of reclaimed asphalt and degree of blending with recycling agents

It is common practice to assume full blending of the aged binder of reclaimed asphalt (RA) within the design of new asphalt mixtures. Although being practical, this assumption has often led designers to asphalt mixtures lacking binder. Hence, going towards recycled asphalt mixtures (RAM) there is a need to have a better understanding of the blending phenomena, to have a general agreement on terminology and finally adapting RA classification and mix design procedures accordingly. This manuscript aims at being both a reference and stimulus for the scientific community to work in this direction and on this basis provides a nomenclature and a theoretical framework of the blending phenomena. The study is built upon a literature review on definitions, methods and influencing factors related with the blending phenomena and as a result, an intrinsic property of RA, the Degree of binder Activity (DoA), is introduced for the sake of improving RA classification. Furthermore, the two well-known concepts of the Degree of Blending (DoB) and the Degree of binder Availability (DoAv) are redefined, within the proposed framework, together with practical suggestions to introduce them in mix design procedures