Search results for "PAV"
showing 10 items of 368 documents
A new procedure to determine the rheological properties of RAP binder and corresponding bituminous blends
2017
Abstract In this paper, a new and simple approach to estimate the rheological properties of Reclaimed Asphalt Pavement (RAP) binder is proposed to overcome the limitations of the conventional extraction procedure. This method is based on Dynamic Shear Rheometer tests performed on mortars composed of RAP fine fraction and virgin binder, together with a new back-calculation solution. The properties of the bituminous blends of virgin and RAP binders are obtained with a modified Nielsen model. The Voigt model is then successfully used to estimate complex modulus and phase angle of the RAP binder from the properties of the back-calculated binder blend. This procedure would prevent the need of RA…
Linear viscoelastic properties of high reclaimed asphalt content mixes with biobinders
2017
The use of high Reclaimed Asphalt (RA) content mixtures together with binders produced from renewable resources (biobinders) is one of the current challenges in pavement engineering research. On the one hand, RA has been used for decades, but there are still some concerns about its performance, especially when high contents are used (>30%). On the other hand, biobinders are relatively new materials, which have to be deeply characterised and studied in order to develop good practices for their use. In this paper, linear viscoelastic properties of biobinders and bio-mixtures manufactured with high RA content and biobinders are analysed and discussed. High-modulus mixtures with 50% RA were…
Investigation on Application of Basalt Materials as Reinforcement for Flexural Elements of Concrete Bridges
2015
Basalt polymers are rather new materials for civil engineering; therefore, identification of peculiarities and limitations of application of such polymers in concrete structures (particularly bridges) is of vital importance. This paper experimentally investigates deformation behaviour and cracking of flexural elements, which are predominant parameters governing serviceability of the bridges. Unlike a common practice, the present study is not limited by the analysis of concrete beams reinforced with the polymer bars; it also considers effectiveness of basalt fibre reinforced polymer sheets for repairing the beams. The analysis has revealed that a combination of the high strength and elastici…
Performance of asphalt mixes with high recycling rates for wearing layers
2016
The corresponding paper presents selected results of a research on the feasibility of going toward 100% recycling of asphalt pavements into surface courses through an increasing percentage of RA within the mixes. The research is carried out within a two-year CEDR Transnational Road Research project, AllBack2Pave, led by the Technische Universitaet Dresden (Germany), together with the University of Nottingham (UK) and the University of Palermo (Italy), and finalised in January 2016. The main objectives of the project are - to establish, through laboratory tests on binders and asphalt mixes, whether the use of high rates of RA is feasible in developing mixes with high level of durability, and…
Influence of bio-based additives on RAP clustering and asphalt binder rheology
2017
The use of high Reclaimed Asphalt Pavement (RAP) content in Hot Mix Asphalt (HMA) allows developing innovative materials for the construction and/or rehabilitation of sustainable infrastructures. The chemo-physical phenomena occurring during production of HMA containing high RAP content should be investigated and considered for the mix design optimization. In fact, when additives are used as rejuvenators of the aged bitumen, these phenomena can be affected causing significant variations in the mixture characteristics. This paper aims at studying the influence of two bio-based additives specifically on RAP clustering, phenomena which can significantly affect the performance of high-content R…
Physical characterization of alginate-Pluronic F127 gel for endoluminal NABDs delivery
2014
Here we focus the attention on the physical characteristics of a highly biocompatible hydrogel made up of crosslinked alginate and Pluronic F127 (PF127). This is a composite polymeric blend we propose for artery endoluminal delivery of an emerging class of molecules named nucleic acid based drugs (NABDs). The physical characterization of our composite gel, i.e. mesh size distribution and PF127-alginate mutual organization after crosslinking, can significantly determine the NABDs release kinetics. Thus, to explore these aspects, different technical approaches, i.e. rheology, low/high field NMR and TEM, were used. While rheology provided information at the macroscopic and nano-level, the othe…
Evaluation of Subgrade Resilient Modulus Predictive Model for Use in Mechanistic-Empirical Pavement Design Guide
2006
The characterization of unbound materials in the mechanistic–empirical pavement design guide (MEPDG), also known as the 2002 design guide, is reviewed, and this characterization is applied to Minnesota subgrades. The main emphasis is on the collection of k1-, k2-, and k3-parameters for Minnesota fine-grained soils and the procedure for the interpretation of the resilient modulus test to provide an input to the multilayer elastic theory (MLET) analysis (Level 2 input). This is an important aspect of adaptation of the MEPDG, because the guide recommends measurement of resilient moduli from laboratory testing, but the procedure does not specify how to interpret the test data to obtain an input …
An advanced pavement management system based on a genetic algorithm for a motorway network
2013
Maintenance and improvement, through the rehabilitation, of the road infrastructure is a strategic and priority objective for road agencies, nevertheless the economic resources required are often inadequate. Within road management, the pavement management system (PMS) plays an essential role because of both the money needed and the performance that should be provided in terms of safety, ride quality and transport cost. The PMS is based on searching for a balanced solution between the lowest cost and the increased level of performance (i.e. pavement condition). In this paper a PMS multi-objective optimization method, was proposed, using a genetic algorithm (GA) to identify the best solution …
Rietumu medusbites (Apis mellifera L.) būtiskāko parazītisko mikrosporīdiju (Nosema spp.) un ērču (Varroa destructor) izplatību un sastopamību ietekm…
2019
Medusbišu, tāpat kā citu apputeksnētāju, skaita samazināšanās Eiropā un pasaulē kopumā saistāma t.sk. ar parazitārām slimībām. Šī pētījuma mērķis ir izpētīt Rietumu medusbišu (Apis mellifera L.) būtiskāko parazītu (Nosema spp., Varroa destructor) izplatību un sastopamību ietekmējošos faktorus Latvijā. Laikā no 2012.-2013. gadam ievākti bišu paraugi no 274 dravām, lai noteiktu to invāzijas slimību sastopamību Latvijas teritorijā. Pētījumā konstatēta Nosema spp. prevalence 49,5% un vidējā intensitāte 8,5x105 sporas uz vienu biti. Savukārt V. destructor prevalence bija 52,3% un vidējā intensitāte 3,0 ērces uz 100 bitēm. Būtiskākie parazītu sastopamību ietekmējošie faktori bitēs Latvijā bijā se…
Retās un apdraudētas augu sugas jūrmalas zilpodzes (Eringium maritimum L.) pavairošana in vitro un audu fenolu saturs atkarībā no barotnes sastāva
2016
Jūrmalas zilpodze (Eryngium maritimum L.) ir Latvijā reta un apdraudēta suga, kura ir ierakstīta Latvijas Sarkanās grāmatas 1. kategorijā. Latvijā jūrmalas zilpodzes izplatību ierobežo piemērotu biotopu trūkums un sēklu mazā dīgtspēja. Zilpodzei ir liela nozīme Eiropas tradicionālajā medicīnā, jo tā satur dažādus bioaktīvus savienojumus ar daudzveidīgu farmakoloģisko aktivitāti. Darba mērķis bija uzsākt jūrmalas zilpodzes augu audu kultūru un izmēģināt šīs sugas mikropavairošanas metodes, kā arī noteikt kopējā fenolu satura izmaiņas atkarībā no barotnes sastāva. Lai iesāktu kultūru, kā sākotnējo eksplantu izmantoja sēklas, kuras diedzēja aseptiskos apstākļos. Jūrmalas zilpodzes mikropavairo…