1,721,058 research outputs found
Un modello idrologico-idraulico per la progettazine e la gestione di opere di controllo del deflusso in un bacino di bonifica del territorio Ferrarese
No full textPer la corretta progettazione e gestione delle opere di controllo del deflusso in un bacino di bonifica idraulica è stato fatto uso di una modellistica idrologico-idraulica in grado di riprodurre, da un lato, il processo di trasformazione piogge deflussi nelle zone agricole ed urbane, e, dall’altro, il processo di pro-pagazione nei canali di drenaggio, tenendo conto sia delle varie opere di sezionamento utilizzate nella sta-gione irrigua per il controllo dei livelli idrici, sia delle opere di accumulo. In particolare, in questa memoria si mostra come la modellistica proposta consenta (a) di verificare la validità della scelta del posizionamento della cassa di espansione e di valutare al tempo stesso la sua area di influenza, (b) di relazionare l’andamento dei livelli con il grado di apertura delle paratoie dei sezionamenti, ottenendo così un controllo automatico del loro grado di apertura che si riflette in un netto contenimento dei livelli e la conseguente riduzione della per-centuale dei tratti dei canali soggetti ad esondazione
Mixed Design Optimization of Polymer-Modified Asphalt Mixtures (PMAs) Containing Carton Plastic Packaging Wastes
Full text linkThis study investigated the potential of reusing plastics derived from multilayered food carton recycling processes as a modifier for asphalt mixtures by dry process. Two types of plastics, one untreated and one pelletized, were added to a mixture containing neat asphalt binder using three different dry methods and in two different amounts (2 and 5% by weight of aggregates). The chemical and physical properties of the plastics were explored via differential scanning calorimetry (DSC) and laser diffraction granulometry. The fracture behavior of the polymer-modified asphalt (PMA) mixtures was evaluated via superpave indirect tensile (IDT) testing at 10 °C and comparative analysis with the reference and a mixture composed of the same aggregate curve and a traditional styrene–butadiene–styrene (SBS)-modified asphalt binder. The role of the plastic during crack initiation and propagation was investigated via microscopic analysis. The results show that plastics derived from carton recycling processes can be successfully used as an additive in asphalt mixtures via the dry method due to the compatibility between their melting and mixing temperatures. The shape of the plastics influences the cracking propagation and resistance of the mixture. Finally, the presence of plastics in the mixture reduces the proneness to accumulate deformation (about 50% less than the reference ones) and increases the failure resistance, leading to a better cracking response at intermediate temperatures
Active filler’s effect on in situ performances of bitumen emulsion recycled mixtures
No full texthis paper address the in situ performance over time of different bitumen emulsion stabilized mixtures blended with different types of fillers (cement, lime and mineral filler), monitored during the first year from construction. Results are part of a more extensive research program aimed to investigate the effects of using lime as active filler in cold recycled mixtures, both with bitumen emulsion and foam bitumen. A specific test track has been designed on a construction road near Florence in order to evaluate the evolution of mixture performance over time. Shortterm bearing capacity has been evaluated by means of LWD (Lightweight tests)after 4 h from compaction while FWD tests have been performed after 24 h,14 days, 28 days and 9 months to monitor the mid-term performances. Up untilmid-2014 tests road was not yet opened to traffic so the mixtures experienced onlyconstruction traffic loads. Results obtained positively support the use of lime as active filler in the bitumen emulsion stabilized material and underline the effect of different blends of fillers in the material behaviour. FWD tests are scheduled to be repeated every 6 months in order to monitor the stiffness evolution of the mixtures and evaluate the nature of traffic damage. © RILEM 2016
Microstructural and rheological investigation of asphalt mixtures containing recycled asphalt materials
No full textIntroducing a new test protocol to evaluate the rate of damage accumulation in mastics at intermediate temperatures
No full textAsphalt mastic, the combination of fine-grained mineral particles and asphalt binder, plays a significant role on the performance of Hot Mix Asphalt mixtures. A clear understanding of the effects of both filler and asphalt binder, and their interaction, on the properties of HMAs is critical to ensure a proper mix design and pavement performance. Several researchers have studied the response of the mastic in terms of fatigue, rutting and fracture resistance using different load configurations and equipments. However, a fundamental interpretative model of mastic behaviour, that is intrinsic to that particular filler-asphalt binder combination, has not been defined yet. This study presents a new prototype test in direct tensile configuration to evaluate the rate of damage accumulation of the mastic at intermediate temperatures. The results presented are preliminary and are intended to evaluate the feasibility of developing an interpretative model of mastic at intermediate temperatures in terms of energy dissipation
Swelling Potential and Performance Level of Hot Mix Asphalt Containing Not-Hydrated Ladle Furnace Steel Slags as Filler
No full textNowadays, the use of carbon-neutral materials is an urgent need because of energy consumption and CO2-emissions concerns. Thus, the use of ladle furnace steel slags (LFSs) is becoming common in asphalt pavement fields. One of the limitations on using LFSs is linked to swelling potential because of the changes in chemical structure due to the hydration of their components. In this study, two different asphalt binders, neat and 3.5 % styrene-butadiene-styrene modified, were mixed with limestone coarse aggregates and two fillers (limestone and LFSs) to analyze the swelling potential and the performance levels of hot mix asphalts containing not hydrated LFSs as filler. The analysis was conducted performing the SuperPave indirect tensile test protocol at 10 & DEG;C and by using a 3D-digital image correlation metadata model (3D-DICM) capable of computing the volumetric expansion of materials after four different periods of conditioning in water (24, 48, 168, and 336 h). The results showed no significant differences among the analyzed materials, highlighting that the volumetric expansion is mainly linked to the aggregates' water absorption. On the other hand, conditioning time seems to affect the deformability of the mixtures, influencing performance level
Evaluation of cement treated mixtures with high percentage of reclaimed asphalt pavement
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