Rosolino Vaiana

Improving infrastructure sustainability in suburban and urban areas: is porous asphalt the right answer? and how?

The goal of this paper is to investigate transportation infrastructure sustainability from a wider standpoint. A sustainable transportation infrastructure can be defined as a safe, efficient, economic, environmentally friendly infrastructure meeting the needs of presentday users without compromising those of future generations. This concept involves environmental, economic and societal aspects. In more detail, as for a road, a sustainable infrastructure or pavement must comply with environmental, economic and social requirements. Unfortunately, even if a definition of a sustainable pavement for urban or suburban areas can be easily proposed, the proposal of practical strategies to really pursue sustainability goals is sometimes disregarded in favour of emphatic announces of not well defined sustainable solutions. In the light of the above facts, the sustainability of a transportation infrastructure based on the actual environmental, social and economic characteristics is discussed in this paper. Once the main factors which can influence infrastructure sustainability are assessed, an analysis is performed in order to set out practical strategies for pursuing the main objective. Finally an experimental investigation is designed and carried out in order to assess porous asphalt value in terms of pavement sustainability. The tests carried out are promising about the possibility of achieving suitable levels of overall performance. Practical applications and perspectives in rehabilitation, maintenance, and research are outlined.

Pavement Sustainability: Permeable Wearing Courses by Recycling Porous European Mixes

The main objective of this research is the formalization of strategies and technical procedures for recycling porous European mixes (PEMs) back to permeable wearing courses. A number of issues were studied: mitigating the drawback of clogging and its related consequences (decay of acoustic and permeability performance over time); preserving traditional (bearing properties, skid resistance) and premium (quietness, permeability) performance; recycling high percentages of cold-milled reclaimed asphalt pavement (RAP) from PEM; and investigating the collateral effects in terms of sustainability. To investigate the aforementioned issues, an experimental plan was designed. Mixes with high RAP contents were produced and tested. Design and construction features, including mix design and mixing procedures, were addressed. Even if other experiments are needed, mechanical and environmental properties are promising. Furthermore, the tests carried out are encouraging regarding the possibility of achieving a satisfactory level of surface performance. Practical applications for rehabilitation intervention are outlined.

Recycling PEMs back to TLPAs: Is that Possible Notwithstanding RAP Variability?

Porous European mixes, PEMs, are porous asphalts which when compacted have an air void content usually in excess of 20%. PEMs points of strength are reduction of splash and spray, mitigation of outdoor noise, optimization of skid resistance at high speeds in wet conditions. Conversely, PEMs have quite low bearing properties, clogging, variation of volumetrics over the time, variation of noise, texture, friction, and permeability performance over the time. Furthermore, at the end of their lifecycle many issues arise: RAP variability, uncertainties on the potential for high percentage recycling, potential for recycling a surface layer back to a surface layer. Based on the abovementioned facts, objectives and scopes were then focused into the analysis of the feasibility of a two-layer porous asphalt (TLPA) by recycling from-PEM RAP, when highly variable rap stockpiles are involved. The following main issues were addressed: mitigating the clogging and its related consequences (acoustic and drainability performance over the time); preserving traditional (bearing properties, skid resistance) and premium (silentness, drainagebility) performance; recycling high percentages of from-PEM RAP. Materials selection was followed by mixtures production. Traditional and advanced tests on RAP and recycled mixes were carried out. RAP variability was examined and a method for facing its consequences was proposed. Mechanical performance was adequate and environmental compatibility was achieved. Functional performance resulted very promising. Results are encouraging about the possibility of achieving a satisfactory level of surface performance. Practical applications and perspectives in rehabilitation, maintenance, and research are outlined.

Transport and traffic management by micro simulation models: operational use and performance of roundabouts

The performance of roundabouts can affect urban transport systems in terms of environmental and operational impacts, safety and efficiency. The development of roundabout traffic management and control systems can be carried out through road traffic micro-simulation models which are computer models where the movements of individual vehicles travelling around road networks are determined by using simple car following, lane changing and gap acceptance rules. Unfortunately, despite the great diffusion of these tools, appropriate methods are still needed in order to validate and calibrate these models. In general, the calibration process can be defined in this way: the process of comparing model parameters with real-world data to ensure that the model realistically represents the traffic environment. The objective is to minimize the discrepancy between model results and measurements or observations. The aim of this paper is the presentation of a first comparative approach between observed performances and performances obtained by the use of popular microsimulation software, in particular urban intersections such as roundabouts. In particular, an experimental investigation is designed and carried out in order to acquire some vehicular parameters for a roundabout placed in an urban contest of southern Italy. The calibration process is carried out by an analysis of variance of the kinematic parameters of an n-tuple of roundabout scenarios. This calibration procedure has permitted to derive some important conclusions about the choice of the most significant input parameters for the output results of each simulation scenario. Outcomes of this study are expected to benefit both practitioners and researchers.

Sustainable Rehabilitation of Porous European Mixes

The objectives and scopes of this research were confined into the formalization of strategies and technical procedures for recycling PEMs back to permeable wearing courses. The most relevant boundary conditions were the following: mitigating the drawback of clogging and its related consequences (decay of acoustic and drainagebility performance over the time), preserving traditional (bearing properties, skid resistance) and premium (silentness, drainagebility) performance; recycling high percentages of cold milled RAP-from-PEM, investigating on collateral effects in terms of sustainability. An experimental plan was designed and carried out, by specifying materials selection, production, tests on recycled PEMs, basic and advanced tests on surface and hydraulic properties of recycled PEMs, analyses and reports. Functional performance resulted quite promising and the tests carried out are encouraging about the possibility of achieving a satisfactory level of surface performance. Practical applications for rehabilitation interventions are outlined.

Dependence of Volumetric Parameters of Hot-Mix Asphalts on Testing Methods

AbstractAssessing the volumetrics of hot-mix asphalts (HMAs) is an important aspect of quality-control and quality-assurance procedures. The economic value of HMAs is usually assessed in terms of their mix bulk specific gravity (Gmb), air-void content, voids in mineral aggregate, and voids filled with asphalt. However, the results for specific gravity can vary with the coring process and method used in the experimental measurements. In light of these concerns, this study focused on the assessment of the dependence of the measured volumetrics of HMA-wearing courses on the testing and coring procedures. A wide range of methods for the measurement of specific gravities and surface texture was considered. Analyses showed that the coring process, measurement methodology, and core diameter can all substantially affect the results of HMA volumetrics measurements; the effects of the selection of the testing technique are not negligible and can be critical. At the same time, results demonstrate that there is poten...

Effect of Asphalt Mix Properties on Surface Texture: An Experimental Study

Pavement surface characteristics play an important role in accident occurring, especially in wet conditions: the optimization of surface performance starting from hot mix asphalt (HMA) design phases is a fundamental requirement in road construction techniques. Although such relevance, the prediction of surface properties based on HMA composition and construction still calls for further research. Indeed, there is not a clear framework for a mix design oriented to surface properties. In the light of the abovementioned facts authors efforts were focused into the analysis of the most significant factors influencing pavement surface macrotexture, by analyzing the main variables of existing macrotexture prediction models. Many experimental mixes were designed and produced. Some statistical correlations between macrotexture data and mixes grading and volumetric properties were also carried out. Outcomes of this study are expected to benefit both practitioners and researchers.

Methodological Approach for Evaluation of Roundabout Performances through Microsimulation

In the literature, there are many methodologies that allow the evaluation of roundabout performances (Capacity, Levels Of Service, etc.): analytical models (HCM, HBS etc.), statistical models (TRRL, SETRA) etc. Each technique considers some aspects of the roundabout in comparison to others (geometric elements, vehicular flow and behavioral parameters). Obtained results are often not comparable among themselves because of distinctive peculiarities of each method. Today, the best way to solve this problem is by using a refined simulation software of vehicular circulation. However, along with a more and more refined analysis of microsimulation software algorithms, it is frequently necessary for each user (researcher, engineer, planner, etc.) to know the real sensitivity of these packages with regard to the most important key parameters. In this paper the Authors introduce the results of a wide survey conducted on an ample range of virtual roundabout scenarios by the use of a modern simulation software. Each scenario describes a fixed roundabout phenomenon using the following variables: geometric elements (inscribed circle radius, circulatory roadway, central and splitter islands etc.); characteristics of the traffic flow (dynamic traffic assignment, approach speed, circulatory speed and reduced speed zones, etc.); behavioral features (priority rules, minimum gap, minimum headway, etc.). The results are presented from the evaluation of stop-line delays.

Highly stable surfactant-crumb rubber-modified bitumen: NMR and rheological investigation

In this paper the properties of a new modified bitumen with crumb rubber (CR) additive and stabilising surfactants (a fatty acid – FA and an organosilane OS) are investigated. The characterisation of the surfactant-CR binder has been conducted by a set of laboratory tests, as penetration, softening point and Fraass breaking point, and by comparison with a reference neat bitumen and a CR modified bitumen. Dynamic shear rheometer (DSR) tests and nuclear magnetic resonance relaxometry (T2-NMR) were used to investigate the rheological properties and the molecular interactions of both pristine and modified bitumen. The stability of the bitumen systems was determined by the Tuben test method. Experimental results suggest a clear improvement of the viscoelastic properties of the modified bitumen. All data show that surfactant-CR binder features comply with standard requirements. Surfactant modification, in fact, is crucial because it allows using CR as a modifier with elimination of its separation during transportation and storage at high temperature.

Permeable Wearing Courses from Recycling Reclaimed Asphalt Pavement for Low-Volume Roads: Optimization Procedures

The recycling of reclaimed asphalt pavement (RAP) in hot-mix asphalt (HMA) is an important opportunity in regard to transportation infrastructure construction and maintenance because it helps to achieve more sustainable road transport systems (reduction of waste production and reduction of resource consumption). In particular, totally recycled HMAs can be a good alternative for road paving even if performance can be an issue. As is well known, the type of low-volume road pavement (gravel, coarse rocky soil, crushed aggregate, cobblestone, concrete block, or some type of bituminous seal coat or asphalt pavement) depends on traffic volume, native in-place soils, and the need to control surface and depth erosion. The objectives and scope of this research were confined to the formalization of strategies and technical procedures for recycling RAP from porous asphalt concretes to obtain permeable wearing courses for low-volume roads. Different solutions were investigated. High percentages of RAP were used in the recycling process, and traditional and advanced tests on RAP and recycled mixes were carried out. RAP variability was examined, and a method for facing its consequences was proposed. Mechanical performance was adequate. Recycling porous European mixes could be a proper way to achieve environmental sustainability in pavement construction, as the functional performance results are very promising and encouraging. Practical applications and perspectives in rehabilitation, maintenance, and research are outlined.