1,720,961 research outputs found
PERFORMANCE EVALUATION OF CEMENT STABILIZED CUPOLA SLAG FOR ROAD PAVEMENT SUBBASE LAYERS
No full textThe Use Of Lightweight Materials In Road Embankment Construction
No full textAbstractConstruction overload on high compressive soils can cause significant settlements as to require the design of an appropriate soil treatment, including load compensation, aimed to hold the stress-strain state present in the soil when undisturbed. Lightweight materials, both natural and/or derived from industrial process, can be used to solve the problem of replacement of large volumes of material. This paper presents some preliminary results obtained from comparative tests on both natural lightweight materials and geofoam samples. Results focus on the possibility to reach adequate performance, allowing lightweight materials to be used for innovative applications such as airport pavement subgrades and embankments
In situ Characterization of Self-cementing Properties of Recycled Materials
No full textIn the last years, the emerging environmental & financial issues has led the international scientific community to spend more and more research efforts on the use of recycled materials in road construction, encouraging the standardization committees to modify their
references. In some Countries the re-use of construction materials is becoming mandatory, reaching high percentages of recycling materials overall the aggregates used in road constructions. In this context the release of specifications, based on in situ performance criteria, assumes greater importance enabling the widespread use of secondary raw materials. The saving up due to the use of recycled materials covers both the economic aspects (reduced supply of virgin materials) and the environmental ones (lower quarrying of inert material and less dumping of waste materials) related to the infrastructure works. The
correct understanding of the on time behaviour of recycled materials, particularly those containing significant quantities of crushed concrete, is of fundamental importance in order to ensure their proper design and built on. The aim of this paper is to highlight the selfcementing
properties of recycled materials, according to the evolution of the stiffness characteristics assessed at different curing times, using non destructive devices (LWDFWD).
Tests carried out with these instruments allow high levels of reliability guaranteeing more detailed investigation, thus increasing the data available for Qc/Qa. The tests were performed on a trial field consisting of 4 different types of recycled materials. Results show a significant increase in stiffness, expressed in terms of Surface Modulus, as a function of the curing time. The analysis of data acquired by some pressure cells located at the base of the recycled layer allows confirming the increase of stiffness of the materials shown by the
deflection test results
Dynamic field assessment of bearing capacity for pavement subgrades and foundations
No full textIn situ assessment of bearing capacity is usually performed by means of static plate loading tests. Today, however, higher performance dynamic investigation methodologies are increasingly often employed, in combination with traditional and deflectometric techniques. This allows a large amount of data to be recorded rapidly, thereby guaranteeing more detailed investigation, but also making the process of data elaboration and result interpretation more time-consuming. In the present study, an improvement in data elaboration techniques and interpretation of results was achieved through application of geostatistical science to measurement and analysis of data acquired at several experimental sites. The findings suggest that geostatistics-based systems have the potential for use as quality control/quality assurance (Qc/Qa) devices in testing subgrades, subbase courses and compacted soil layers and as a means of evaluating their correspondence to the strength performances required for the layers. Concomitant use of various deflectometric systems also made it possible to take specific construction and operating characteristics of the devices into account when evaluating the experimental results. This paper reports on joint experiences conducted by the Universities of Pisa and Bologna, whose research teams have long been working on validation of innovative field testing systems. The results appear promising for upcoming insertion of the methodologies inserted into existing technical specifications
Comparing Light Weight Deflectometers to standardize their use in the compaction control
No full textAlong with the increase of road traffic and loads, arises the need for a methodology for studying and predicting the rutting resistance of asphalt concretes. The growth of this phenomenon on the asphalt pavement is directly connected with the layers’ structural damage and it is reflected in terms of safe riding. An accurate laboratory characterization of the material rutting performance is desirable, aiming to reduce the distresses during its lifetime and to predict the mixture tendency to develop excessive permanent deformations under repeated heavy traffic loading.
This paper reports a case study concerning the evaluation of the mechanical characteristics of two Warm Mix Asphalts (WMA). A unique binder type was adopted to reduce the number of variables, since it is known that one of the primary cause which engender the rut distress is the plastic behavior of the binder. These analysis were carried out with different tests setup complying with the EN 12697-25 requirements, varying stress level, but keeping constant temperature, loading type and time
A preliminary comparison of Continuous Compaction Control and Portable FWD systems for Qc/Qa
No full text
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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