1,720,978 research outputs found
Expanded polystyrene (EPS) in road construction: Twenty years of Italian experiences
Full text linkExpanded polystyrene (EPS) is a thermoplastic material, derived from pre-expanded polystyrene beads, that combines an extreme lightweight with versatile strength and thermal insulation. These characteristics made EPS an excellent alternative to natural materials for the feasibility of building and construction projects that would otherwise destined, for time and implementation costs, to be postponed or alienated. Specifically, this technology has been successfully used in road infrastructure sector in the last twenty years in the construction of roads, bridge abutments, lightweight embankments and backfills, above all for the rapid restoration of compromised roads following landslide or calamitous events, representing an interesting and resilient solution in areas exposed to seismic risk or persistent vibratory actions. Thus, the authors want to offer a critical analysis of different EPS road applications in Italy, considering benefits and drawbacks, proposing technical and economic considerations for ideal conditions of use and suggesting failure analysis methods and tools. © 2020 The Author(s)
The influence of laying patterns on the behaviour of historic stone pavements subjected to horizontal loads
No full textStone pavements are of great importance both for their historical and cultural value and for the most modern ecological and aesthetic requirements appreciated thanks to the use of natural materials of different colours, shapes and sizes which are laid in different patterns. Since stone block pavements are made up of individual elements with irregular side surfaces that interact with each other, an important parameter that must be considered in the design is their structural strength to horizontal stresses mainly due to braking, turning and accelerating vehicles. In this study horizontal load tests were performed on stone pavements built in a wide laboratory test chamber to analyse the load-shifting behaviour for different geometric arrangements. The displacements distribution of the elements was determined by a photogrammetric analysis. The tests have shown that the behaviour of the stone pavements in the horizontal plane is significantly influenced by the laying pattern, both in terms of translations and interaction between the elements. © 2020 Elsevier Lt
Criteria for the selection and design of joints for street pavements in natural stone
No full textNatural stone pavement can produce a high quality attractive streetscape with a long service life. Although the formal analogy with the interlocking concrete pavements, the peculiarities and singularities of the stone elements pose enormous challenges to the designers which have at their disposal only limited standards and guidelines. The joints represent one of the most important part of the stone paving system, performing multiple tasks: stabilize the elements, transmit and dissipate loads, control the water disposal and contribute to the aesthetic. But, the analytical study of the joints is inexplicably an understudied topic in the technical and scientific literature: many problems resulted in stone pavements from lack of understanding of joints’ purposes and functions. Thus, the paper highlighted the conceptual steps necessary to the selection of the optimal jointing solution. Several aspects related to the stone elements’ characteristics and laying that contribute to the joints’ optimized performance have been evaluated. After a brief description of the main defects that can affect stone pavements, a state of practice regarding the jointing materials with the related application techniques have been reported. © 2020 Elsevier Lt
Advanced thermal and rheological characterization of a sustainable anti-icing hydrogel for winter road maintenance operations
No full textAs a part of the advancements in the winter road maintenance, a sustainable anti-icing hydrogel has been recently developed for the treatment of the open-graded asphalt pavements. It is obtained by mixing water, a chemical agent and a phyto-based additive (seaweed fiber powder) having thickening and gelling properties. The product has the ability to form a gel-like structure when hot-sprayed on a cold pavement surface. The influence of the interaction between the solutes, i.e. sodium chloride (marine salt) and seaweed fiber, on the gel behavior was evaluated through a laboratory scale study, based on thermal (differential scanning calorimetry) and rheological (rotational and oscillatory tests) analyses. The research findings offer a substantial support for the definition of most suitable recipe and the configuration of the spray application system. The results revealed that the formulation of the anti-icing hydrogel is predominantly governed by the salt concentration, which establishes the freezing point depression capacity. Once the salt dosage is defined on the basis of the climatic condition and the accepted level of service, the gellant content, which controls the gelation mechanism, can be optimized to obtain a sprayable gel with a sufficient stiffness and strength
Electronic nose for smart identification of roofing and paving grade asphalt
No full textAsphalt is a complex mixture of hydrocarbons, whose properties strongly depend on the source and type of crude oil and refining processes. From a technical standpoint, intensive investigations carried out by the construction sector, above all by road researchers, have attempted to understand relationships between asphalt binder chemical structure, morphology and physical characteristics. Nevertheless, one challenge that the advance research on asphalt products actually face is to transfer this extremely high level of knowledge to applied industrial technologies for finding easy-to-use, quick and cost-effective test methods for quality control and identification of asphalt binders at refinery, terminal and plant. Thus, this paper focused on the development of a protocol for fingerprinting, including identification and discrimination, of asphalt cements using two different electronic noses (e-noses), also known as artificial olfactory systems (AOS). E-nose is a biomimetic non-destructive intelligent sensing instrument, which is designed to mimic the human sense of smell to detect, compare and classify odor sample, producing a qualitative output (fingerprint). Results suggested that a complementary combination of electronic nose technique and well-established analytical methodologies could be successfully used for the identification and discrimination of roofing and paving grade asphalt cements. Specifically, both sensing instruments were able to perform a good discrimination between products characterized by a different chemical nature and to verify the refinery process stability during production and a batch-to-batch crude oil consistency. © 2019 The Authors. Published by Elsevier B.V
Conservare le finiture all'aperto: gli intonaci esterni dipinti a Mantova. Prime considerazioni e proposte.
No full textSimplified parametric model for analyzing the behavior of stone pavements subjected to horizontal traffic loads
No full textUrban stone pavements have always represented the historical and cultural value of a city. They are appreciated thanks to the use of natural materials of different colors, shapes and sizes that are laid in different laying patterns, responding not only to structural requirements but also to ecological and aesthetic needs producing an attractive landscape. Since stone block pavements consist of individual elements with irregular side surfaces that interact with each other, an important parameter that must be considered in the design is their structural resistance to horizontal stresses mainly due to braking, turning and acceleration of vehicles. In this work, the possibility of using a parametric model to study the behavior of pavements made of stone cubes subjected to horizontal loads was analyzed. Each stone element was modeled by a rigid body while the inter-elements and element-ground interactions using specific features that allow to insert a visco-elastic interaction among the bodies and the limits to failure, distinguishing between tension and compression. This model has allowed to analyze, at the same mechanical parameters (stiffness, damping, etc.), the behavior of such pavements subjected to horizontal loads as a function of laying pattern and the dimensions of the stone cubes. From the modeling, it has emerged that both the size of the elements as well as their laying pattern have a relevant influence on the behavior of the stone element pavements subjected to horizontal loads and must therefore be considered in the design
A study for the understanding of the Roman pavement design criteria
No full textThe authors present the suggestive hypothesis that Romans possessed specific and specialized pavement design criteria, from which the most appropriate construction techniques and the majestic road infrastructures descend. From a back-analysis of some road pavements, it emerged that there is a good correspondence between thicknesses and materials selection used by Romans and those arising from the calculation by analytic methods introduced only in the modern age. In this paper, some considerations, from the point of view of road engineer, were presented; these could be usefully shared with the researchers in the fields of cultural heritage and archeology in order to identify both soils and road pavement materials sampling and classification systems for a new perspective of scientific speculation
Use of bending beam rheometer test for rheological analysis of asphalt emulsion-cement mastics in cold in-place recycling
Full text linkThis paper focused on exploiting the potential of the bending beam rheometer (BBR) test for analyzing asphalt emulsion-cement (AEC) mastics tailored for cold in-place recycling applications in the first weeks of curing, i.e. phase which implies the coexistence of viscoelastic and brittle materials. A consistent modified BBR testing protocol, which includes the experimental solutions devised for the practical execution of these unconventional rheometric measurements (sample preparation and test procedure), was proposed. The authors suggested to introduce glass microspheres, acting as "inert solid skeleton", in the production of AEC mastics for BBR prismatic beams, to study the interaction between asphalt emulsion and cement in thin film and to limit the specimens' shrinkage and warpage during the curing period. Finally, a feasibility study for validating the new modified experimental setup was presented, highlighting, with an explanatory overview of the types of results that can be expected, the macroscopic behaviors of some AEC mastics as a function of different parameters (asphalt binder to cement ratio, curing time and temperature). (C) 2019 Elsevier Ltd. All rights reserved
Half-warm mix asphalt with emulsion. An experimental study on workability and mechanical performances
No full textOne of the major sustainability-related challenge facing materials for asphalt pavements is the energy consumption and the release of harmful and odorous fumes. Reductions in these emission levels have been progressively achieved by a number of cleaner and low-temperature technologies. Recently, a further step towards an improved road pavement sustainability is represented by the half-warm mix asphalt (HWMA) mixtures, which are produced between 70 °C and 100 °C without negatively affecting their final performances. Among these methodological approaches, a very interesting solution for urban or low volume traffic roads is represented by HWMA mixtures prepared with a conventional warm emulsion and heated aggregates. Although this technique is capable of combining the advantages of hot and cold mixes, limiting some drawbacks, it is still little known and remains confined only to some regional areas (in Spain with the term mezclas templadas). There are no standards or specifications, but only some construction practices resulting from the experience gained in the field. Thus, a laboratory-scale experimental study was set up to analyze in detail the behavior of dense-graded HWMA mixes prepared with emulsion intended for a surface course layer of a low or medium traffic road. The objective was to evaluate the influence of three mix-design variables, such as compaction temperature, binder content and aggregate gradation on the volumetric and mechanical, i.e. indirect tensile strength and moisture susceptibility, properties of these mixtures. The rank comparison between the selected mixtures represented the starting point for improving on the one hand the mix-design process and on the other the operational procedures of production, transportation and placement
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