Search results for "Fatigue resistance"
showing 8 items of 8 documents
Reclaimed asphalt binders and mortars fatigue behaviour
2017
Fatigue cracking is one of the most important failure mechanisms occurring in asphalt pavements, especially when mixtures incorporate considerable amount of rReclaimed asphalt pavement (RAP). In fact, aged binders contained in RAP generally make asphalt more brittle and specifically reduce fatigue resistance of the resulting asphalt mixtures. Binders and mortars play a key role in this phenomenon, considering fatigue cracking usually starts within these asphalt components. However, performance-related tests and specifications commonly regard binders and there are no sound methodologies allowing the use of mortars to predicting fatigue performance of asphalts containing RAP. For this reason,…
The effect of paired associative stimulation on fatigue resistance
2015
Paired associative stimulation (PAS) is a non-invasive stimulation method developed to induce bidirectional changes in the excitability of the cortical projections to the target muscles. However, very few studies have shown an association between changes in motor evoked potentials (MEP) after PAS and behavioral changes in healthy subjects. In the present study we hypothesized that the functional relevance of PAS can be seen during fatiguing exercise, since there is always a central contribution to the development of fatigue. Transcranial magnetic stimulation was applied over the motor cortex to measure changes in the MEPs of the soleus muscle before and after PAS. Furthermore, fatigue resis…
Production of innovative, recycled and high-performance asphalt for road pavements
2010
Abstract The paper deals with a specific laboratory study aiming at perfectioning recycled asphalt with high mechanical performance, for surface and structural layers of flexible pavements. The aim of the research was to combine in the same material the maximum possible quantity of recycled asphalt (RA), coming from degraded asphalt layers, together with high structural performance of the recycled mixtures obtained (mainly stability, load spreading properties, rutting and fatigue resistance) that should not be lower, or possibly better than those offered by traditional asphalt mixture, made with virgin binder and aggregate. For this purpose, innovative recycled mixtures, close-graded and wi…
THE RESISTANCE TO FATIGUE OF DRY ASPHALT RUBBER CONCRETE FOR SUB-BALLAST LAYER
2015
The more and more frequent use of recycled materials within the road and railway infrastructures is now an irreversible trend. In this area the use of Dry Asphalt Rubber Concrete (DARC) in sub-ballast layer seems to be a suitable technique to reach high mechanical and environmental performance even if such material should be analyzed over a long time horizon. This paper presents the results of experimental research focused on the resistance to fatigue of Dry Asphalt Rubber Concrete in sub-ballast layers; the survey has been carried out using four-point bending test (4pbt) on mixture samples with different rubber contents. The results of fatigue in DARC have been compared with the performanc…
Functionalisation of MoS2 2D layers with diarylethene molecules
2021
Functionalisation of two dimensional (2D) materials with stimuli-responsive molecules has been scarcely investigated. Here, MoS2 layers obtained by chemical exfoliation are covalently and non-covalently functionalised using two photoswitchable diarylethene derivatives under their open- and closed-ring isomers. The choice of these light-responsive molecules is based on their excellent thermal irreversibility and fatigue resistance. The characterisation of the resultant molecular/2D heterostructures proves the successful anchoring of the molecules by both approaches as well as the influence that the driving interaction has in the photoswitching behaviour of the diarylethene isomers after thei…
AA6082-T6 Friction Stir Welded Joints Fatigue Resistance: Influence of Process Parameters
2006
In the paper the results of a wide range of experiments on friction stir welding (FSW) of aluminium alloys are reported. In particular, the AA6082-T6 butt joints fatigue resistance was investigated by varying the most relevant process parameters. In addition, a revolutionary pitch was utilized in order to investigate the effects of the tool rotating speed and the tool feed rate. Observations of the fracture insurgence were developed for different levels of applied load.
Fatigue resistance: is it possible having a unique response?
2012
The mechanical characterisation of the asphalt concrete in terms of both the fatigue resistance and the stiffness modulus is necessary to use any design method of the flexible road pavements. Different kinds of test are usually used in experimental work such as bending tests, uniaxial tests, etc., but sometimes they do not give the same answer. In this paper mechanical characterization was carried out by means of fatigue tests undertaken with two most used testing machines for asphalt material: two point bending (2PB) test at IFSTTAR in Nantes (France) and four point bending (4PB) test at University of Palermo, in Palermo (Italy). Different strain controlled tests were undertaken for the sa…
Improvement of high modulus asphalt mixtures with average quality aggregate and bitumen by application of polymeric additives
2018
Abstract The paper deals with the development of asphalt mixtures for high performing binder and base courses, modified with both commercial and waste polymeric additives, via dry process. The focus was on the mix design of high performing mixtures making use of average quality aggregate and average penetration grade bitumen (as locally available) instead of the usually required high quality components, manly very hard bitumen, thus aiming to improve the reference mixture as made possible by suitable polymers. Mixtures were subjected not only to conventional tests for mix design purposes, but also to advanced tests for performance evaluation such as rutting resistance and fatigue resistance…