1,720,994 research outputs found
UNA CORRELAZIONE ANALITICA FRA IL COSTIPAMENTO MARSHALL E CON PRESSA GIRATORIA DEI CONGLOMERATI BITUMINOSI
No full textCONVEGNO NAZIONALE SIIV, PARM
Compaction characteristics assessment of cold mix patching materials through gyratory shear compactor
No full textCold mix patching materials (CMPMs) are widely employed in pothole repair due to ease of installation and
environmental benefits. In order to generate long-lasting pavement repairs, CMPMs must guarantee adequate
volumetric properties, which in turn determine a proper pavement serviceability. In this context, the present
study aims to provide an improved understanding of the compaction process of CMPMs through a laboratory
campaign based on gyratory compaction tests carried out under a wide range of energy. To this end, the volu
metric response of nine ready-to-use CMPMs and the evolution of shear stress along their densification process
have been investigated at different temperatures.
Based on both densification and shear stress curves, two modelling approaches are here presented by the
authors. Results demonstrate that the proposed s-shaped function enables densification curves to be studied with
a high reliability and provides distinctive parameters to characterize the CMPMs at different stages of
compaction. Moreover, the analysis of shear stress data through a two-stage model highlights a certain corre
lation among physical and mechanical responses of studied mixtures
A Cement-Bitumen Emulsion Grout as Backfilling Material of Narrow Trenches on Road Pavements
No full textNarrow trenching on road pavement has become a widespread practice for installing telecommunication infrastructures on road pavements. Although such technique guarantees a social and environmentally sustainable construction, the quality of the backfilling plays a crucial role in both the short- and long-term properties of the trench. In this context, the present research aims to assess the effectiveness of a cement-bitumen emulsion grout (CBEG) as unique backfilling material for narrow trenches. To this purpose, a real-scale field trial was constructed and monitored through visual inspection, coring activity, and permeability tests. Skid resistance tests, compressive and flexural strength tests were also carried out on specimens casted in the laboratory. Moreover, indirect tensile strength tests were performed to evaluate the adhesion properties at the existing pavement backfilling interface on both cored and laboratory moulded specimens. Results mainly show that the CBEG, due to its flowable nature, quick hardening, and great early strength, provides uniform backfilling and fast restoration of the pavement surface. The latter shows skid resistance values comparable to those of hot mix asphalt pavement. After long curing, the backfilling does not show any lowering phenomenon and ensures adhesion at the interface as testified by the absence of water penetration. Finally, a satisfactory adhesion at the interface is determined also in terms of indirect tensile strength
INFLUENZA DEL GRADO DI COSTIPAMENTO SULLE CARATTERISTICHE MECCANICHE DEI CONGLOMERATI BITUMINOSI.
No full textINFLUENCE OF ENVIRONMENTAL CONDITIONS ON SLIDING FRICTION MEASURES CARRIED OUT WITH A SKID-TESTER.
No full text
Resilient Modulus of Recycled Aggregates Obtained by Means of Dynamic Tests in a Triaxial Apparatus
No full textAbstractThe main objective of this experimental research is to prove the hypothesis of the use of recycled materials (C&D) in building road subbases by means of a comparative study which investigates the resilient behaviour of unbound aggregate blends.The results given by the investigation clearly prove that the blend made of recycled materials has shown a resilient behaviour very similar to that of a typically frictional material, such as a virgin granular material coming from quarry aggregates.A low susceptibility to water and a marked influence of confinement pressure on the blend stiffness are the properties which prove this similar behaviour
A new analytical approach for stiffness loss modelling of asphalt mixtures under cyclic indirect tensile loadings
No full textIn this study, the indirect tension mode of loading was used to investigate the fatigue behavior of both modified and unmodified asphalt mixtures. Experimental data were analyzed by studying the evolution of the stiffness modulus with the number of cycles. A new analytical approach was introduced to model the variation of the material stiffness and determine different phases of testing. The material response under the selected mode of loading was then characterized based on a damage parameter that refers to the quasi-stationary stage of testing. Moreover, the damage parameter, normalized by a specific stiffness value, was used to provide a general fatigue law where the fatigue life of materials is determined independently from mixture composition. Results prove that good correlations can be established
RELATIONSHIP BETWEEN THE SUPERFICIAL AND STRUTTURAL CHARACTERISTICS OF PAVEMENTS: THE BINDER RHEOLOGICAL CONTRIBUTION IN THE FRICTION PHENOMENON
No full textNaturalistic driving data collection to investigate into the effects of road geometrics on track behaviour
No full textRoad designers assume that drivers will follow the road alignment with trajectories centred in the lane, and move at the design speed parallel to the road centreline (i.e., the horizontal alignment). Therefore, they assume that if the horizontal alignment indicates the ‘‘designed trajectory", the driving path indicates the ‘‘operating trajectory". However, at present, they do not have the necessary tools to measure the relationship between the designed alignment and possible vehicle trajectories. The paper has two objectives: (a) to develop an understanding of the root causes of differences between road alignment and vehicle trajectories; and (b) to define and calibrate a model that estimates the local curvature of trajectories on the basis of the designed horizontal alignment. The two objectives were pursued by carrying out a naturalistic survey using vehicles equipped with high precision GPS in real-time kinematics (RTK) mode driven by test drivers on road sections of known geometric characteristics. The results provide an insight into the effects of road geometrics on driver behaviour, thus anticipating possible driving errors or unexpected/undesired behaviours, information which can then be used to correct possible inconsistencies when making decisions at the design stage
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