The BIM (Building Information Modeling)-Based Approach for Road Pavement Maintenance

The recent developments of road pavement survey technologies guarantee acquisition of detailed data regarding the main functional and structural indicators, at a very high frequency and levels of accuracy and precision unconceivable few years ago. The relevant information, regarding surface distresses too, is thus available in economical, high-speed and high-resolution forms, with limited disturbance on traffic and road agencies issues. However, the availability of such a mass of data poses interesting questions concerning the most efficient processing and analysis methods, for optimizing maintenance operation planning. Unfortunately, the PMS adoption is not very common and widespread, as t…

Criteria for Laboratory Studies on Fine Soils Treated with Lime

When selecting the appropriate materials for constructing road infrastructures, an important way for minimizing both the economical and environmental impact is to make use of lime for treating those natural soils that, involved in the earthwork for opening road fences, are not suitable, as they are in nature, to fulfill the specific requirements for being used as part of road construction, such as road embankments (including the capping layer) or the improved subgrade or, again, the sub-formation. From this point of view, the treatment of fine soils with lime (if needed, with lime and cement) can be considered as one of the main measures for preserving the natural environment since it fulfi…

Digital image analysis technique for measuring railway track defects and ballast gradation

Abstract In order to guarantee safety and driving comfort and to maintain an efficient railway infrastructure, the first step is to carefully monitor the track geometry and wear level of the materials constituting the superstructure. To that end diagnostic trains are widely used on main lines, in that they can detect several geometric track parameters and rail wear, but under no circumstances they can yet detect ballast gradation. Due to the practical implications for the planning of maintenance operations on the railway network, this article presents a “DIP” digital image processing technique for measuring the transverse profile and corrugations of the rails as well as ballast gradation. T…

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

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. …

Il quadro degli interventi avviati e programmati in sicilia a favore della sicurezza stradale

Il volume intende illustrare il tema della sicurezza stradale nelle sue molteplici dimensioni e in maniera trasversale, con uno specifico approfondimento per la Sicilia, mettendo a disposizione un'ampia selezione di informazioni qualitative e quantitative per specifiche analisi sulla sicurezza stradale, utili ai policy maker per intraprendere azioni di programmazione a livello locale. L'Italia registra un elevato tasso di mortalità rispetto alla media europea, una lenta riduzione del numero di vittime per incidente stradale e marcati divari territoriali. Nel contesto nazionale questo studio descrive poi l'evoluzione del fenomeno dell'incidentalità in Sicilia nell'ultimo decennio, individuan…

UNA PROCEDURA AUTOMATIZZATA PER LA DETERMINAZIONE DELLE CURVE MAESTRE DI BITUMI PER USO STRADALE

Study of a structural change in bitumen induced by the photooxidation aging method

Definition of a laboratory optimization protocol for road bitumen improved with recycled tire rubber

Abstract Bearing in mind the need to answer one of the most frequent needs for civil construction, in general, and major project such as road infrastructures in particular, this paper presents the results of a laboratory experimental study in order to evaluate the performance improvement that is possible to achieve when modifying road bitumen with CRM (Crumb Rubber Modifier) from discarded tire rubber (TR), using a Wet Process. The environmental advantage is double, since the aim of the research is to obtain high performance road bitumen thanks to the re-use of a discarded material, such as the rubber tires, which otherwise would be dumped in scrap-yard. In particular, this experimental stu…

CARATTERIZZAZIONE GEOTECNICA DI UN’ARGILLA DI ALTA PLASTICITAꞌ TRATTATA CON CALCE

Nel corso dei lavori di ammodernamento di una strada di grande comunicazione in Sicilia, si è valutata la possibilità di utilizzare come materiale di costruzione un’argilla di alta plasticità trattata con calce, proveniente dagli scavi eseguiti in una parte del tracciato. A questo scopo è stata avviata un’estesa ricerca sperimentale in laboratorio e sono state verificate le condizioni di posa in opera del materiale con la realizzazione di un rilevato sperimentale. Nella nota si illustrano i primi risultati della ricerca riguardanti: prove di taglio diretto, prove di compressione ad espansione laterale libera e misure di suzione.

Il sostegno al rafforzamento dei nodi logistici di servizio alle imprese

Numerical Comparison of the Hydrological Response of Different Permeable Pavements in Urban Area

Floods are becoming more frequent, especially in urban environments where most of the surface is waterproofed. Permeable pavement (PP) can be applied as low impact development (LID) systems for runoff mitigation in urban areas. Their effectiveness can be assessed, case by case, by numerical simulations. In this study, the effectiveness of mitigating runoff of different permeable pavements has been evaluated. In particular, porous asphalt (PA), pervious concrete (PC), permeable interlocking concrete pavement (PICP) and grid pavement (GP) have been investigated using EPA Storm Water Management Model (SWMM) software. To this aim, a car parking area located in the University Campus of Palermo (…

Volumetric Behaviour of Lime Treated High Plasticity Clay Subjected to Suction Controlled Drying and Wetting Cycles

The paper presents some experimental results collected on samples recovered from an experimental embankment obtained by compacting a lime-treated clay. Samples were collected soon after the in situ compaction and they were cured in controlled environmental conditions for at least 18 months. Mercury intrusion porosimetry tests (MIP) were carried out on freeze-dried specimens to characterize the microstructure of the material. In order to assess the durability of the improved material, laboratory tests focused on the effects of cyclic variations of the degree of saturation on the water retention properties and the volumetric behaviour of the stabilized clay. Collected results show that the li…

Primary Data Collection and Environmental/Energy Audit of Hot Mix Asphalt Production

The development of the road construction sector determines the consequences on consumption of non-renewable resources, energy expenditure and environmental pollution. Recent sustainability issues have highlighted the importance of efficient design and quality-oriented techniques in this sector, due to the huge amount of materials involved in construction and maintenance activities. Thus, it is necessary to properly quantify the environmental impacts of asphalt mixtures used for pavement construction, considering the whole life cycle of the products. Life cycle assessment (LCA) represents the most appropriate methodological framework for assessing the environmental burdens of a product, from…

Preliminary Evaluation of Plasmix Compound from Plastics Packaging Waste for Reuse in Bituminous Pavements

Finding an appropriate technical solution for reusing waste plastics is crucial for creating a circular plastic economy. Although mechanical recycling is the best option for recycling post-consumer plastics, some heterogeneous mixed plastics cannot be recycled to produce secondary material due to their very low properties. In this case, alternative routes should be considered in order to limit their disposal as much as possible. Therefore, in order to solve the environmental problems in the landfills of plastic waste recycling, and to improve the mechanical performance of bitumen for road pavement, the reuse of these post-consumer plastic wastes are preliminarily evaluated for the modificat…

Prova di campo per i lavori di trattamento delle terre argillose con calce per lavori stradali e ferroviari [Field test of lime treatment of clayey soils for railways and road works]

Si presentano i risultati di una prova di campo svolta su un rilevato sperimentale appositamente progettato e costruito per le finalità del trattamento con calce delle terre argillose. Tale prova di campo è stata sviluppata nell’ambito dei lavori di ammodernamento di una infrastruttura di grande comunicazione in Sicilia, per consentire il reimpiego delle argille di risulta dagli scavi previsti in progetti nella costruzione delle parti in rilevato della stessa. Il programma sperimentale messo a punto si è pertanto concentrato sull’identificazione e la caratterizzazione geotecnica delle argille di scavo al fine di definire le modalità esecutive del loro trattamento con calce. Attraverso le pr…

Asphalt surface mixtures with improved performance using waste polymers via dry and wet processes

"Published online: June 29, 2017"

Interazione veicolo-strada: guida alla valutazione e pianificazione degli interventi di risanamento acustico.

Analysis of the chemical and microstructural modifications effects on the hydro-mechanical behaviour of a lime-treated clay

The paper presents the results of a characterization of kinetic characteristics of pozzolanic reaction with the aim to investigate the time-dependent modification of clay properties as a consequence of mixing with lime. Results of chemical analyses are in agreement with the increase of mechanical properties and with the observed microstructure modifications up to one year of curing time. The rate of development of pozzolanic reactions seems to be almost constant while the time required for their completion is dependent on the lime content. Pozzolanic products are responsible for the time reduction of swelling strain upon saturation as well as for the increases of yielding stress, stiffness …

The way forward for pavement performance indicators across Europe - Final Report COST Action 354

Investigation of the procedure to determine asphalt binder viscosity in the new AASHTO pavement Design Guide

Evaluation of the laboratory prediction of surface properties of bituminous mixtures. Construction and Building Materials. Volume 23. Issue 2. Elsevier Ltd, Amsterdam. ISSN: 0950-0618 pp. 943–952

An experimental and analytical investigation was carried out both in laboratory and in situ on wearing courses. The approach presented in this paper aims to predict the in situ density and surface properties of bituminous layers, during the phase of mix design in laboratory. Therefore, the main attempt of this study is to identify, amongst the commonly available laboratory equipments, the most adequate for producing specimens that, used for carrying out simple and reliable laboratory test, allow the prediction of the surface characteristics of the mixture as laid on site. This is done by comparing the data collected from an experimental site with those calculated from laboratory specimens c…

A machine learning approach to determine airport asphalt concrete layer moduli using heavy weight deflectometer data

An integrated approach based on machine learning and data augmentation techniques has been developed in order to predict the stiffness modulus of the asphalt concrete layer of an airport runway, from data acquired with a heavy weight deflectometer (HWD). The predictive model relies on a shallow neural network (SNN) trained with the results of a backcalculation, by means of a data augmentation method and can produce estimations of the stiffness modulus even at runway points not yet sampled. The Bayesian regularization algorithm was used for training of the feedforward backpropagation SNN, and a k-fold cross-validation procedure was implemented for a fair performance evaluation. The testing p…

LCA of an Asphalt Mixture Produced in a Southern Italian Plant: Analysis and Perspectives

In recent years, a growing attention on environmental issues affecting all fields and procedures of the productive sectors has raised, aiming to reduce energy and raw-material consumptions and pollution effects on environment. Due to the involved volumes and to the nature of the related materials and productive processes, the civil and road sectors have been strongly invested by this change of perspective. Therefore, a proper estimation of the environmental impacts for the entire life cycle of the asphalt mixtures for road construction and maintenance activities is extremely important. For performing similar investigations, Life Cycle Assessment (LCA) has become one of the most reliable and…

Rumore stradale: ruolo ed efficacia delle pavimentazioni fonoassorbenti nella riduzione delle emissioni sonore

Experimental validation of a fractional model for creep/recovery testing of asphalt mixtures

Abstract Prediction of asphalt mixtures’ behavior during their service life is a challenge due to its complexity and sensitivity to environmental and loading conditions. It has been proved that, when subjected to loading conditions comparable with most pavement operating conditions, asphalt mixtures behave as linear visco-elastic (LVE) materials. Traditionally the LVE behavior of bituminous material is modeled via creep/recovery functions. In the past, several rheological models constituted by elastic and viscous elements arranged in series or in parallel (analogical models) have been proposed and specified for both bitumen and asphalt mixtures. The corresponding constitutive laws always in…

PREVISIONE DA PROVE DI LABORATORIO DELLA COMPATTEZZA DEGLI STRATI BITUMINOSI IN OPERA.

An extension of the fractional model for construction of asphalt binder master curve

Knowledge and prediction of viscoelastic behaviour of asphalt binder is of great interest in order to design asphalt mixtures for civil construction of road and airports with good performances. The capability of a fractional model – requiring a very limited number of parameters – to describe and predict the linear viscoelastic behaviour of asphalt binder subjected to sinusoidal oscillations is investigated. Experimental data of complex modulus, |G*|, and phase angle, δ, are used to validate the proposed constitutive model. Based on the proposed extension of a fractional model, complex modulus isotherms for a range of frequencies can be created simply starting from isochronals at frequency v…

Environmental analysis of different construction techniques and maintenance activities for a typical local road

Abstract In this paper, considering the sever impact of road infrastructures on both the surrounding environment as well as on the consumption of locally available natural resources, different road construction techniques have been studied and compared, in order to be able to rank the best solution in terms of environmental sustainability. For the aims of this study, a Life Cycle Analysis has been carried out on a road infrastructure with the most representative geometrical characteristics among those widely used in Italy, in suburban areas, with the help of an appropriate software, the PaLATE. The environmental effects due to both the use of recycled materials, such as the Reclaimed Asphal…

On the hydro-mechanical behaviour of a lime-treated embankment during wetting and drying cycles

Abstract The paper presents some experimental results obtained on samples extracted from a full-scale embankment obtained by compacting a lime-treated clayey soil. A comprehensive test programme was carried out in order to highlight the improvement of mechanical behaviour induced by lime treatment as well as to assess the durability of the improved material, which may be affected by severe seasonal wetting and drying cycles. Direct shear tests, triaxial compression tests, swelling potential measurement and oedometric tests were performed on samples cured in controlled environmental conditions for at least 18 months. Wetting and drying cycles were applied in a very wide range of suction valu…

Backcalculation of airport pavement moduli and thickness using the Lévy Ant Colony Optimization Algorithm

Interpretation of NDTdata is crucial in any Airport Pavement Management System (APMS), in order to implement strategies to maintain airport pavementssince they allow to estimate their remaining life and related maintenance needs and activities. In this paper, the AntColony Optimization algorithmwasused for backcalculation of pavement moduli from surface deflection data. The algorithm’s performances are illustrated and improvement in prediction quality is demonstrated both in terms of goodness of fitness and computational effort. Moreover, it is proved that the proposed algorithm is also able to predict layer thicknesses, taking into account their variation too.

Improvement of high modulus asphalt mixtures with average quality aggregate and bitumen by application of polymeric additives

Abstract The paper deals with the development of asphalt mixtures for high performing binder and base courses, modified with both commercial and waste polymeric additives, via dry process. The focus was on the mix design of high performing mixtures making use of average quality aggregate and average penetration grade bitumen (as locally available) instead of the usually required high quality components, manly very hard bitumen, thus aiming to improve the reference mixture as made possible by suitable polymers. Mixtures were subjected not only to conventional tests for mix design purposes, but also to advanced tests for performance evaluation such as rutting resistance and fatigue resistance…

LCA of Different Construction Choices for a Double-Track Railway Line for Sustainability Evaluations

The international commitment to achieve carbon neutrality in the next few decades has oriented human activities towards the preservation of natural and non-renewable resources. In this context, a great research effort has been devoted to the search for sustainable solutions for the infrastructure construction sector, based on a thorough assessment of the environmental impact (EI). In this regards, Life Cycle Assessment (LCA) is considered one of the main components of Environmental Impact Assessment (EIA) and, for a comprehensive analysis, all the costs incurred by stakeholders during the useful life of the infrastructure should also be taken into account, applying the Life Cycle Cost (LCC)…

Effect of climate change on asphalt binder selection for road construction in Italy

This work explores the influence of climate changes on the proper selection of asphalt binder for pavement construction purposes, according to the Performance Grade (PG) defined in the SUPERPAVE specifications. Based on temperature data at national level, it is possible to obtain thematic maps for the whole Italian territory, which is extremely useful for technicians and pavement engineers for selection of asphalt binder for road construction purposes. Furthermore, the statistical significant temperature trends’ knowledge enables deriving thematic maps which allows to include the effects of climate change in the asphalt binder design. It is argued that, due to climate change, the binders to…

Influence of short-term aging on mechanical properties and morphology of polymer-modified bitumen with recycled plastics from waste materials

Polymer-modified bitumen (PMB) is bitumen that has been specifically engineered with polymer for providing enhanced performance in service. The aging of bitumen is a main aspect that is able to affect its final performance: during the production phase in a hot mix plant, all the binders experience short-term aging due to the high processing temperature. The same is true during the production of the modified binder, when the polymer is dispersed at high temperature in the bitumen mass. This paper aims at studying the effect of short-term aging when using different types of modifiers such as recycled polymers obtained from waste materials. A 50/70 penetration-grade bitumen has been modified, …

Caratterizzazione geotecnica di un’argilla trattata con calce posta in rilevato

Nelle nota si presentano alcuni risultati di un’indagine di laboratorio eseguita su campioni indisturbati prelevati da un rilevato sperimentale, realizzato trattando con calce i terreni argillosi provenienti dallo scavo di una vicina galleria artificiale. La ricerca è stata sviluppata nell'ambito dei lavori di ammodernamento della S.S. 640 tra Agrigento e Caltanissetta. I risultati, oltre ad evidenziare gli usuali effetti derivanti dalle modifiche delle caratteristiche geotecniche dell’argilla indotti dai processi di stabilizzazione con calce, consentono di evidenziare alcune peculiarità del comportamento meccanico delle argille trattate.

Prediction of Airport Pavement Moduli by Machine Learning Methodology Using Non-destructive Field Testing Data Augmentation

For the purpose of the Airport Pavement Management System (APMS), in order to optimize the maintenance strategies, it is fundamental monitoring the pavement conditions’ deterioration with time. In this way, the most damaged areas can be detected and intervention can be prioritized. The conventional approach consists in performing non-destructive tests by means of a Heavy Weight Deflectometer (HWD). This equipment allows the measurement of the pavement deflections induced by a defined impact load. This is a quite expensive and time-consuming procedure, therefore, the points to be investigated are usually limited to the center points of a very large mesh grid. Starting from the measured defle…

Evaluation of the laboratory prediction of surface properties of bituminous mixtures

Abstract An experimental and analytical investigation was carried out both in laboratory and in situ on wearing courses. The approach presented in this paper aims to predict the in situ density and surface properties of bituminous layers, during the phase of mix design in laboratory. Therefore, the main attempt of this study is to identify, amongst the commonly available laboratory equipments, the most adequate for producing specimens that, used for carrying out simple and reliable laboratory test, allow the prediction of the surface characteristics of the mixture as laid on site. This is done by comparing the data collected from an experimental site with those calculated from laboratory sp…

Analisi della microstruttura di un'argilla di alta plasticità trattata con calce

Nella nota si presentano i primi risultati di una indagine sperimentale volta a studiare l’effetto del trattamento con calce sulle caratteristiche microstrutturali di un’argilla di alta plasticità, proveniente dagli scavi eseguiti nel corso dei lavori di ammodernamento di una strada di grande comunicazione in Sicilia. I provini, compattati in laboratorio a diverse percentuali di calce, sono stati sottoposti a prove porosimetriche ad intrusione di mercurio MIP ed osservazioni al microscopio elettronico SEM. L’analisi dei risultati evidenzia che l’argilla trattata con calce assume una distribuzione dei pori tipica dei materiali a doppia porosità e che gli effetti sulla microstruttura dipendon…

Rumore da traffico: elementi per la valutazione e pianificazione del risanamento acustico

Ruolo del Nucleo di Valutazione per l´attivazione delle procedure per la predisposizione dello schema di APQ per la logistica ed il trasporto merci in Sicilia

Il presente contributo riferisce dell´esperienza del Nucleo della Sicilia —Area Valutazione progetti, in merito alla redazione della relazione tecnica di accompagnamento all´APQ per il Trasporto delle Merci e per la Logistica in Sicilia. Partendo dalle Disposizioni contenute nella delibera CIPE n.20/2004 e dalle indicazioni della nota di indirizzo Rete NUVV dic/2004 in proposito, il gruppo di lavoro ha proceduto alla necessaria acquisizione delle informazioni e dei dati relativi a ciascun singolo intervento previsto in APQ, ricostruendo i processi e le procedure, come pure la sequenza tecnico-procedurale con la quale si sono sviluppate le proposte (analisi del fabbisogno, individuazione deg…

Performance improvements of asphalt mixtures by dry addition of polymeric additives

This paper shows the results of an experimental study concerning the development and optimization of asphalt mixtures for binder and base courses, improved with specifically engineered additives. The focus was on the mechanical improvements of the mixtures as achievable via dry modification with polymeric additives by making use of aggregate and bitumen of average quality, as locally available, in order to limit the consumption of virgin materials. The results allowed interesting conclusions to be drawn about the use of polymeric additives for these mixtures. In particular, the modified mixtures proved to have better performance in terms of both permanent deformation resistance and stiffnes…

Il contesto infrastrutturale siciliano e il quadro normativo di riferimento

Il volume intende illustrare il tema della sicurezza stradale nelle sue molteplici dimensioni e in maniera trasversale, con uno specifico approfondimento per la Sicilia, mettendo a disposizione un'ampia selezione di informazioni qualitative e quantitative per specifiche analisi sulla sicurezza stradale, utili ai policy maker per intraprendere azioni di programmazione a livello locale. L'Italia registra un elevato tasso di mortalità rispetto alla media europea, una lenta riduzione del numero di vittime per incidente stradale e marcati divari territoriali. Nel contesto nazionale questo studio descrive poi l'evoluzione del fenomeno dell'incidentalità in Sicilia nell'ultimo decennio, individuan…

Improved Traffic Signal Detection and Classification via Image Processing Algorithms

An image analysis technique for automatic traffic sign detection and classification is proposed. This analysis makes it possible, after proper training, to detect, recognize and classify vertical road signs from video frames acquired on a moving vehicle equipped with cameras, as well as to identify anomalies with respect to road sign regulations (positioning and visibility). The experimental results show that this technique allows one to correctly detect and classify almost all vertical signs and, mainly in extra-urban environment, it can be considered as highly reliable, apart from being really versatile and user-friendly for road inventory and road maintenance purposes.

TECNICHE E ASPETTI NORMATIVI DEL RICICLAGGIO NELLE PAVIMENTAZIONI STRADALI

Microstructure and shear strength evolution of a lime-treated clay for use in road construction

The results of a comprehensive experimental programme are presented for assessing the long-term microstructural modifications and evaluating the effects of microstructural rearrangement on the stress–strain behaviour of a lime-treated high-plasticity clay for road embankments. The stress–strain behaviour at different lime content and curing time was investigated by means of direct shear tests; microstructural analyses were carried out combining Scanning Electron Microscope observations and Mercury Intrusion Porosimetry tests. The results show that the stress–strain behaviour of treated clay is strongly dilatant with a high peak of strength, which increases with time and lime content. Furthe…

Laboratory and in-situ tests for estimating improvements in asphalt concrete with the addition of an LDPE and EVA polymeric compound

Abstract Pavement deformation is a critical issue in the design of pavement structures and the related mixture. Asphalt concretes may be very sensitive to this problem, in compliance with the viscoelastic behaviour of the adopted bitumen. To improve the material performance, many attempts have been made to introduce in the mixture other materials as “modifiers” or “additives” for increasing the permanent deformation resistance and the elastic modulus of the material. Among the different possible materials, polymers determined significant improvements in the road pavement performance. In this paper, the authors tested the adoption of a specifically engineered polymeric compound, in order to …

Experimental testing for physical and functional characterization of wearing courses

Costruzione dei rilevati stradali e ferroviari: valutazione delle metodologie di progetto delle terre trattate con calce

Nella costruzione delle opere civili e, soprattutto, delle infrastrutture di trasporto, elemento qualificante per la minimizzazione degli impatti economici ed ambientali è l’adozione del trattamento con calce dei terreni argillosi di scavo, di per sé non idonei ad essere impiegati nei manufatti in terra, e la loro utilizzazione - previo trattamento con calce, appunto - per la costruzione di rilevati ed altre opere in terra. La tecnica del trattamento con calce delle terre argillose permette di ottenere diversi vantaggi di ordine tecnico, economico ed ambientale. I progressi tecnologici conseguiti negli ultimi decenni, particolarmente per quanto riguarda gli studi di progetto, i mezzi di can…

Design Procedures for Soil-Lime Stabilization for Road and Railway Embankments. Part 2-Experimental Validation

AbstractAs detailed in Part 1, the most common Italian Technical Specifications refer to different design methodologies for design of lime-soil mixtures, some being quite different from those internationally adopted. Therefore, it seemed appropriate to the Authors to compare these methodologies, via a wide experimental program.It is shown that the Italian methodology of the National Road Agency is different not only from those used in Italy, but also from the main international standards. The experimental results highlight that a revision of that methodology is needed in order to bring it into line with what is prescribed by the European standard.

Modelling pavement surface characteristics for noise prediction through Bailey-related indicators

The aggregate gradation of bituminous mixtures (hot mix asphalts, HMA) is one of the major factors affecting their surface texture. In turn, this latter is a crucial factor and influences drivers and bystanders’ safety, comfort, and health. Despite this, the design of texture levels still lacks sound bases and dedicated algorithms and this negatively affects the acoustic design of bituminous mixtures. Consequently, the objectives of this study were confined into the derivation of relationships to be used in mix design to predict texture levels. Experimental data were analyzed, in the pursuit of setting up appropriate models and algorithms. Analyses involved the consideration of Bailey-relat…

Modeling of the viscoelastic behavior of paving bitumen using fractional derivatives

The paving grade bitumen used in the production of asphalt mixtures for road construction is significantly able to affect the in-service performances of flexible road pavements. It has been proved that, when subjected to loading conditions comparable with most pavement operating conditions, bituminous binders behave as linear visco-elastic materials. The aim of this paper is to propose a model based on fractional differential equations which is able to describe the behavior of bituminous binders in the linear viscoelastic range. Shear creep testing and creep recovery testing were carried out over a range of temperatures and by applying a stress level which makes it possible to maintain the …

Production of innovative, recycled and high-performance asphalt for road pavements

Abstract The paper deals with a specific laboratory study aiming at perfectioning recycled asphalt with high mechanical performance, for surface and structural layers of flexible pavements. The aim of the research was to combine in the same material the maximum possible quantity of recycled asphalt (RA), coming from degraded asphalt layers, together with high structural performance of the recycled mixtures obtained (mainly stability, load spreading properties, rutting and fatigue resistance) that should not be lower, or possibly better than those offered by traditional asphalt mixture, made with virgin binder and aggregate. For this purpose, innovative recycled mixtures, close-graded and wi…

The 2002 Mechanistic-Empirical Design Procedure for Flexible Pavements: How to Implement it in Italy

PROPRIETÀ STRUTTURALI DI CONGLOMERATI BITUMINOSI MIGLIORATI CON PLASTICHE POST-USO

Suction controlled drying and wetting cycle effects on the volumetric behaviour of a lime-treated high plasticity clay

The paper presents some experimental results collected on samples recovered from an experimental embankment obtained by compacting a lime-treated clay. Samples were collected soon after the in situ compaction and they were cured in controlled environmental conditions for at least 18 months. Mercury intrusion porosimetry tests (MIP) were carried out on freeze-dried specimens to characterize the microstructure of the material. In order to assess the durability of the improved material, laboratory tests focused on the effects of cyclic variations of the degree of saturation on the water retention properties and the volumetric behaviour of the stabilized clay. Collected results show that the li…

UNA PROCEDURA AUTOMATIZZATA PER LA DETERMINAZIONE DELLE CARATTERISTICHE MICROSTRUTTURALI DELLE SABBIE MEDIANTE ANALISI DI IMMAGINI DI SEZIONI SOTTILI

È ben noto che il comportamento meccanico microscopico delle sabbie - e in generale dei terreni granulari - trae origine dalle loro caratteristiche microstrutturali, quali, per esempio, il numero di coordinazione dei singoli grani, l’indice di contatto intergranulare (grain contact ratio) e l’indice di addensamento dei grani (packing density index). Appare, quindi, di notevole importanza la determinazione degli indici predetti con alto grado di affidabilità e di ripetibilità. Lo studio dell’assetto dei contatti intergranulari e il calcolo degli indici che lo caratterizzano, viene condotta comunemente su immagini piane dell’insieme di grani mediante esame visuale e restituzione grafica assis…

PG dei bitumi stradali per il territorio italiano

L’ARTICOLO SINTETIZZA IL LAVORO DI RICERCA SVOLTO DALL’UNIVERSITÀ DI PALERMO PER DEFINIRE - SU BASE TERRITORIALE NAZIONALE - LE TEMPERATURE CARATTERISTICHE DETERMINANTI PER LA QUALIFICAZIONE DEI BITUMI, CONFORMEMENTE ALLE SPECIFICHE SUPERPAVE. NE SONO DERIVATE CARTE TEMATICHE DELLE TEMPERATURE MASSIME E MINIME DI PROGETTO DELLE PAVIMENTAZIONI STRADALI CHE I TECNICI POTRANNO UTILIZZARE PER LA SELEZIONE DEI LEGANTI BITUMINOSI.

Environmentally appraising different pavement and construction scenarios: A comparative analysis for a typical local road

Abstract The aim of this work is to carry out a comparative analysis of environmental impacts for different scenarios of a typical local road. Life Cycle Assessment (LCA) is the modeling tool used to quantify and characterize comparative environmental impacts. In carrying out this specific application of the LCA, different road construction techniques were considered with regards to the whole structure and compared in order to identify the best alternative in terms of environmental sustainability. So far, in fact, typical LCA frameworks of roads have focused on recycled materials for pavement layers only, thus neglecting study of the materials used in the embankment or in the subgrade. In t…

Effect of Short-Term and UV Irradiation Aging on the Behaviour of SBS-Modified Bitumen

To obtain road bitumen with improved temperature and fatigue resistance, polymers and/or rubbers could be added to it. A particularly suitable polymer for bitumen modification is styrene-butadiene-styrene (SBS) copolymer but limited information is available about the ageing behaviour of modified binders. In this work, two neat bitumens, with different penetration grades, and two SBS-modified bitumens, containing different SBS amounts, were selected, and their short-term and UVB ageing behaviour were investigated considering dynamic shear rheometry and Attenuated Total Reflectance-Fourier Transformation InfraRed spectroscopy (ATR-FTIR). Short-time ageing behaviour was investigated performing…

An automated procedure for computing the packing properties of dense and locked sands by image analysis of thin sections

The macroscopic mechanical behaviour of dense sands originates to a great extent from their microstructural characteristics such as the coordination number, the grain contact and the packing density indexes. The study of intergranular contacts and the reckoning of these indexes may be carried out on planar images of the grains either by means of time-consuming visual inspection assisted by CAD or by automatic image analysis. An innovative method for the automatic determination of microstructural characteristics of sands based on image analysis of thin section is proposed. Tests performed on a locked sand show that the proposed method is much more effective, convenient and faster than the us…

Modulo resiliente di un’argilla a scaglie trattata con calce come parametro meccanico per l’impiego in strati di sottofondazione stradale

La nota presenta i risultati di un programma sperimentale mirato alla valutazione della possibilità di utilizzare le argille a scaglie trattate con calce come materiale di sottofondo per opere di Ingegneria Civile. Tali risultati evidenziano che le caratteristiche di tale materiale migliorano rapidamente nel tempo e che esso diventa, dopo 28 giorni dal trattamento, molto stabile nei riguardi delle sollecitazioni dinamiche indotte dal traffico veicolare, simulate in laboratorio attraverso l’esecuzione di prove di compressione triassiale cicliche mirate alla misura del modulo resiliente.

Design Procedures for Soil-Lime Stabilization for Road and Railway Embankments. Part 1-Review of Design Methods

AbstractWhen selecting the appropriate materials for constructing road infrastructures, an important way for minimizing both the economical and environmental impact is to make use of lime for treating soils that are not suitable for road or railways construction.Advances in lime stabilization technique allowed the successful use of this technique also for improving the bearing capacity of the subgrade, with noticeable savings on both aggregate and disposal charges.In this paper a review of internationally adopted design methods for soil-lime mixture is presented, in order to compare testing methods and requirements of the adopted criteria, as discussed in Part 2.

Impact Analysis Using Life Cycle Assessment of Asphalt Production from Primary Data

Road construction and maintenance have a great impact on the environment, owing to the huge volumes of resources involved. Consequently, current production procedures and technologies must be properly investigated, for identifying and quantifying the life cycle environmental impacts produced. In this paper, primary data, i.e., site-specific data directly collected or measured on a reference plant, are analyzed for calculating the impact of the production of a hot mix asphalt. The analysis is performed in a from &ldquo

Evaluation of porous asphalt hydrological performances through rainfall-runoff modelling by EPA SWMM

Over the last few decades, the increase in extreme weather events has caused urban floods to become more and more frequent, with increased risks for road users. Among the different types of pavement structures, permeable pavements (PPs) can effectively increase the hydraulic resilience of the cities since they are specifically designed for reducing runoff by allowing water to infiltrate and be discharged into the soil and/or by drains. This study aims at evaluating the hydrological performance of a Porous Asphalt (PA) using numerical simulations for a case study carried out using EPA SWMM (Storm Water Management Model) software. Several simulations have been carried out, considering differe…

Prestazioni migliorate con additivi polimerici

IMPIEGARE I MATERIALI DISPONIBILI SUL TERRITORIO E AD UN TEMPO GARANTIRE ELEVATE PERFORMANCE E DURABILITÀ, NONCHÈ CANTIERABILITÀ ANCHE IN CONDIZIONI CLIMATICHE ESTREME: È LA GRANDE SFIDA DELL’”OTTIMIZZAZIONE” DELLE PAVIMENTAZIONI STRADALI VINTA DALL’INGEGNERIA DEI MATERIALI CON L’AIUTO DEI COMPOUND CONTENENTI POLIMERI. DI SEGUITO, L’ILLUSTRAZIONE DI UN CASO ESEMPLARE DI MODIFICA MIGLIORATIVA DI MISCELE BITUMINOSE, GIÀ PRESENTATO AL RECENTE CONGRESSO TIS 2017 DELL’AIIT A ROMA.

CONGLOMERATI AD ALTO MODULO (EME) MIGLIORATI CON ADDITIVI PLASTICI

A simple interpretation of the effect of the polymer type on the properties of PMBs for road paving applications

Abstract The paper presents the results of the rheological characterisation of polymer-modified bitumen for paving applications. In order to find a simple interpretation of the influence of polymer type on the blends produced, in this study high density and low density polyethylene (PE) with different chemical properties were used, as well as ethylene-vinyl acetate. The chemical characteristics of the base bitumen and the polymers used were determined by means of SARA analysis and Fourier Transform Infrared Spectroscopy, FTIR, respectively. The morphology of the produced blends was investigated by means of fluorescent light optic microscopy, while the mechanical properties were investigated…

Linear ViscoElastic (LVE) Behaviour of Pure Bitumen via Fractional Model

AbstractBy fitting experimental data from static creep/recovery carried out on pure bitumen, it is shown that the fractional model proposed enables the description of both creep and recovery behaviour with fewer parameters than those needed by other models in the literature. In particular, the model is fitted to experimental data of complex modulus |G*| and phase angle δ° obtained from Dynamic Mechanical Analysis. Lastly, it is demonstrated that when the fractional model is used, complex modulus isotherms for a range of frequencies can be created simply starting from isochronals at f = 1Hz.

Effect of the construction process on the performances of asphalt paving mixes with crumb rubber from scrap tires

This paper presents the results of an experimental study on the use of CRM (Crumb Rubber Modifier) in bituminous mixtures for asphalt pavements, using a Dry Process. Employing experimental methods capable of ensuring that the mixtures obtained and the stress conditions that they undergo in pavements are representative, we clarify some aspects relating to the design and production of mixtures; we also show the effects of the bitumen-rubber interaction on mechanical performances (fatigue resistance and rutting). Among the various factors involved in manufacture, a particular investigation was carried out on the effects of asphalt content, mixing temperatures and mixture compaction. The experi…

Evaluation of Subgrade Resilient Modulus Predictive Model for Use in Mechanistic-Empirical Pavement Design Guide

The characterization of unbound materials in the mechanistic–empirical pavement design guide (MEPDG), also known as the 2002 design guide, is reviewed, and this characterization is applied to Minnesota subgrades. The main emphasis is on the collection of k1-, k2-, and k3-parameters for Minnesota fine-grained soils and the procedure for the interpretation of the resilient modulus test to provide an input to the multilayer elastic theory (MLET) analysis (Level 2 input). This is an important aspect of adaptation of the MEPDG, because the guide recommends measurement of resilient moduli from laboratory testing, but the procedure does not specify how to interpret the test data to obtain an input …

EFFECT OF PROCESSING TEMPERATURE VARIATION ON STORAGE STABILITY OF TIRE RUBBER MODIFIED BINDERS

Tire Rubber Modified Binders (TR-MBs), produced through wet process and used worldwide (e.g. asphalt rubber), have been demonstrated to provide various benefits to pavements and, moreover, represent a good opportunity for recycling tire rubber. However, this technology is still struggling to be fully adopted in Europe, mainly because of the poor stability of TR-MBs during high temperature storage, which leads to high initial costs in modifying existing asphalt plants. No-agitation TR-MBs (also known as terminal blends) are proving to be a great option and their development could also be the key to spreading the use of tire rubber in paving applications in Europe. This paper aims to enrich t…

Influence of the Hourly Variation of Temperature on the Estimation of Fatigue Damage and Rutting in Flexible Pavement Design

The work presented in this paper offers a contribution to understand to what extent different discretization modes for describing a whole day can affect the estimation of in-service durability of a flexible pavement, in relation with concomitant traffic flow fluctuations. Calculation of the stress–strain state was carried out with an elastic multi-layer model, and performance laws were implemented for verification of the major distress mechanisms that are able to affect the prediction of a flexible pavement’s service life. Results from the prediction of the fatigue life allow one to conclude that no big mistakes are made when evaluating the total damage by describing climatic conditions via…

Asphalt mixtures modified with basalt fibres for surface courses

Abstract This paper shows the results of an experimental study concerning the effect of introduction of basalt fibres in asphalt mixtures for surface course, mainly with regard to those to be used in urban areas, for dedicated bus lanes. Surface layers, where tire-pavement interactions occur, have to provide different properties such as high friction (very important for users’ safety), stability, resistance to meteorological agents, and contribution to the overall pavement performances. Considering that basalt fibres provide considerable physical and mechanical properties and above all high abrasion resistance, scope of the study is to evaluate the effects of these fibres on mixtures proper…

Valutazione di laboratorio delle caratteristiche di resistenza a fatica dei conglomerati bituminosi contenenti fresato - Laboratory Evaluation of Fatigue Characteristics of Recycled Asphalt Mixture.

Gli Autori presentano i risultati di uno studio mirato alla messa a punto di un nuovo metodo di prova per la valutazione in laboratorio della resistenza agli sforzi tangenziali dei conglomerati bituminosi destinati a costituire strati d’usura. Alla base di un tale sviluppo prototipale, vi è la considerazione della meccanica del contatto pneumatico-pavimentazione, al fine di riprodurre nel modo più realistico possibile l’effetto della sollecitazione tangenziale generata in corrispondenza di punti singolari, dato che proprio per questi punti è più difficile riprodurre in laboratorio la degradazione superficiale cui sono soggetti.

Morfologia ed analisi delle immagini applicate allo studio dei bitumi modificati con polimeri

Vengono presentati i risultati di uno studio di laboratorio condotto su campioni di bitume modificato con diversi tipi di polimeri e precisamente Stirene-butadienestirene (SBS), Etilen-vinilacetato (EVA) ed etilen-butilacrilato (EBA), le cui proprietà fisico-chimiche vengono riportate nell’articolo.