1,720,986 research outputs found
Chemical and Mechanical Evaluation of Construction & Demolition Waste as an Alternative Aggregate for Road Embankments
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Implementation of Deflection Bowl Measurements for Structural Evaluations at Network Level of Airport Pavement Management System
No full textThe APMS is a useful tool for operators and managers, providing a systematic and objective method for pavement condition evaluation, maintenance planning decisions and budget allocation. The pavement evaluation process also includes the evaluation of structural capacity and, more specifically, the use of deflectometer testing device has become a basic part of the structural evaluation, allowing non-destructive and rapid to execute surveys. The measured deflection bowl is used for the back-analysis process, in order to evaluate the modulus of each layer. This application can be less cost effective, requiring experienced analyst and often providing more detail than necessary, especially for implementation at network-level of Airport PMS. These aspects are amplified for seasonal and regional airports, faced with low budget availability and looking for easy and rapid techniques. The investigation reported in this paper focused on developing a direct method for the assessment of the overall conditions as well single layer strength, based on deflections measured by performing HWD tests. The data collected by deflectometer campaign performed on the runway has been analyzed, focusing the attention on the factors that can affect the measurements.
The survey was performed on five alignments, as required by international regulations, in different seasons and with different loads, then the relative influence was examined, conducting a correlation aimed on comparing deflections. With comparable data, the immediately visual rating of deflection values has been conducted, adopting the relative benchmarking methodology. The application at network level of Airport PMS allows the rapid overview of structural conditions, identifying areas that need further detailed investigations
Effects of transition curves on sight distances
Full text linkThis paper presents an ongoing study on the effects of introducing transition curves into an existing road alignment on safety in terms of sight distances and design consistency conditions. Transition curves were firstly adopted in geometric design of railways in order to introduce circular curve naturally and the centrifugal force associated with it gradually in the alignment of transition sections. Later, they were also employed in geometric design of rural roads. In many Countries road geometric standards recommend their use to improve safe conditions. The main objective of the reported study was to evaluate the effect of transition curves on the respect of sight distances and design consistency conditions of a rural road with a high number of car accidents. Existing horizontal alignment of a rural road, with “tangent-to-curve” transition, was analyzed. Sight distances were calculated and verified with the imposed values by standards. Also speed gradients between contiguous elements were analyzed. A new alignment with transition curves and limited works out of the existing infrastructure, to keep the two alignments still comparable, was proposed. Then sight distances and speed variability along the proposed alignment were calculated and verified with the values imposed by the standards. The results obtained revealed that the introduction of transition curves reduces the percentage of verified sight distances along the horizontal alignment. However, different conclusions were obtained analysing the effectiveness of transition curves using design consistency criteria: the new alignment with transition curves have shown a more acceptable speed variation between contiguous elements
Mechanical and Chemical Reliability of Mine Waste Material for Road Embankment and Subgrade
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Sardinia Granite Scraps Application in Road Pavement Layers
Full text linkSardinia is the second-largest island of Italy after Sicily, in this region,
large volumes of granite scraps deriving mainly from the ornamental quarry industry,
lie abandoned in stockpiles. The ornamental query industry, very active in the
region since the late 1900s, has produced large volumes of granite scraps causing
several environmental and landscape issues. Therefore, there is a need to find
potential applications for such materials, previously extracted, for which energy
has already been consumed and CO2 emitted. This research focuses on the possibility
of introducing granite scraps for road construction processes. Achieving
several benefits, ecological by restoring landscape integrity and reducing CO2
emissions, economical by decreasing road construction costs. For this reason,
three types of granite scraps, obtained from the same granitic body using two
types of excavation methods and treatment, were studied. In the first phase of the
research the evaluation of the environmental compatibility of the scraps, based on
Italian regulations, was investigated. Also, chemical, and mineralogical analyses
were performed to establish the correct granite family.Mechanical propertieswere
evaluated to assess the possibility of using them to their fullest extent in booth
unbound and hydraulically bound pavement layers. From the test conducted useful
information were obtained showing how granite scraps, can achieve good physical
and mechanical performances if compared with those of natural aggregates
normally used in road pavement layers. The test conducted demonstrated how
granite scraps can be used with high performances in road pavement structures,
contributing to the reduction of quarrying new materials, and introducing a circle
economy approach with several benefits for the Sardinian Island
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