Kivonat: Jelen kutatási munka különböző ásványi töltőanyagok (mészkőliszt - Miskolc, Mexikóvölgy - és dolomit - Pilisvörösvár) felhasználásával készített aszfalthabarcsok reológiai tulajdonságainak, a finomszemcsés töltőanyagok bitumennel kialakított kapcsolatának feltárásával foglalkozik. Mivel a bitumen és az ásványi töltőanyag közötti kölcsönhatás erőssége az alkotórészek anyagtulajdonságaitól függ, ezért az elvégzett vizsgálatok mind az alapanyagok (töltőanyag, bitumen), mind pedig a belőlük készített aszfalthabarcsok elemzésére is fókuszáltak. Ezek során meghatározásra kerültek a töltőanyagok ásványi összetételei, szemcseméret-eloszlásai; termikus, mikroszerkezeti, és felületi sajátosságai, valamint a felhasznált bitumen (B50/70, Százhalombatta) összetétele és termikus tulajdonságai. Az aszfalthabarcsok reológia vizsgálatának célja az anyagrendszer alakváltozással szembeni ellenállásának, folyási viselkedésének és a töltőanyagok merevítő hatásának vizsgálata volt. Az eredmények ismeretében elmondható, hogy a kutatás során megvizsgált ásványi anyagok – főként a mészkőliszt – aszfalt töltőanyagként történő felhasználása mindenképpen előnyös, ugyanis kedvező tulajdonságaik következtében magas üzemi hőmérsékleten a burkolatok merevsége nagymértékben javítható, az alakváltozással szembeni ellenállásuk növelhető, végső soron csökkenthető a keréknyomosodás kialakulásának lehetősége.
Kulcsszavak: aszfalthabarcs, folyásgörbe, kúszás, mestergörbe, reológia, töltőanyag
Abstract: Eurocode requires seismic analysis and design of bridges. Based on our design and research experiences, it is confirmed that design of Hungarian bridges may be often governed by seismic effects. In this paper, various methodologies to assure safety against seismic events are illustrated through three case studies. First, application of advanced numerical analysis is invoked for the performance assessment of a continuous girder bridge and the achieved beneficial decrease in the calculated seismic forces is shown. Further two examples – a new design and a retrofit application – provide results for comparison of conventional and innovative – seismic isolation – design methods. The discussed problems and the results confirm that application of seismic devices and dampers can be beneficial even in moderate seismic regions, such as Hungary.
Kulcsszavak: alacsony vagy moderált szeizmicitás, csillapító eszközök, modális válaszspektrum analízis, nem-lineáris dinamikai analízis, szeizmikus hatás, szeizmikus szigetelés, szerkezetmegerősítés, új építésű szerkezetek
Témakör: Hidak és műtárgyak
Abstract: The paper introduces a new method for calculating the elastic moduli of the pavement layers. The method requires only two input parameters: the thickness of the upper „bound” layer and the falling weight deflectometer (FWD) measurement data. The authors developed a continuously differentiable regression function, which can be applied to describe the shape of the deflection bowl. Additional parameters of the deflection bowl (e.g. radius of curvature, position of the inflexion point) can be calculated based on the regression function. FWD measurements were simulated running the „BISAR” software on different pavement variations. Outputs of the simulations were further processed with own developed software. As a result, a series of diagrams were elaborated, by which the elastic moduli of the pavement layers can be determined.
Témakör: Kiemelt, Útépítés
Abstract: One of the most important key factors of road safety is the speed of cars. The aim of my study was to find vehicle’s speed effects on road safety with findings of international literature and with analysis of measured speed data. This survey measures drivers’ choice of speed and provides information on the effectiveness of speed enforcement measures. Free speeds are speeds at which drivers choose to travel when unconstrained by road geometry, weather conditions or traffic conditions (e.g. congestion). I proved by analysis of validated speed data of ADR 2000 traffic counters, that average free speeds of cars decreased at examined sites in the last 4 years. I used my self-developed statistical method in this analysis for reliable results. I have found relationship between significant decrease of average free speeds and decrease of injury accidents. I used Nilsson’s Power-model to find this correlation.
Témakör: Kiemelt, Városi közlekedés
Abstract: Due to increasing concerns regarding the availability of SBS polymer, a number of alternative options have been proposed to provide polymer modifiers for the asphalt binder industry. This paper focuses on the evaluation of six specific polymer modified binders: SBS modified binder (PMB), reacted ethylene terpolymer (Elvaloy), ethyl-vinyl-acetate (EVA), asphalt rubber (AR), hybrid binder (SBS and crumb rubber), and polyphosphoric acid (PPA) and SBS. The goal of this project was to evaluate the various modified binders with respect to binder properties as determined by the Multiple Stress Creep Recovery (MSCR) rheological test. The MSCR test was developed as a method to determine the performance of polymer modified binders, as opposed to simply detecting the presence of a modifier. The results indicated that wet process style asphalt rubber and SBS tended to yield the best results; however, hybrid SBS-crumb rubber binder also exhibited good MSCR performance. The process parameters and material compositions in this research were not tailored to Hungarian conditions. The results were used for the latest ASTM and Performance graded (PG) asphalt rubber material standard developments.
Kulcsszavak: AR, bitumen, CRM, Elvaloy, EVA, gumibitumen, ismételt kúszás-relaxáció vizsgálat, módosított bitumen, MSCR, PMB, PPA, reológia, SBS
Témakör: Kiemelt, Kötőanyagok
Abstract: The article studies the stiffness variation of the different manufactured and built-in asphalt mixtures. In the first part of the article the stiffness tests are announced experienced in the course of the SMA-8 asphalt mix production, which was applied in Hungary for the first time. The tests were carried out using not only the indirect tension test (IT-CY) applied in this country but also with the help of the Simple Performance Tester (SPT). The second part of the article contains the stiffness test results of built-in surface and binder layers applied in different projects by different companies. We can gain a picture on the formation of the more popular domestic mixtures after building them in with the help of the stiffness tests carried out on 85 mixtures belonging to the seven asphalt types.
Kulcsszavak: aszfalt, merevség, simple performance tester (SPT), SMA-8 kopóréteg
Témakör: Kötőanyagok, Útépítés
Kivonat: This paper summarizes the results of studies which contributes the safety analysis of different Hungarian two-lane roundabouts (concentric, spiral and turbo) carried out to illustrate the development process of choosing type of two-lane roundabouts. Branch layout and design mistakes of concentric two-lane roundabouts, a missing definition and regulations of multi-lane roundabouts, and handling together with the single-lane roundabouts has become an obstacle to the spread of it. Instead of forced adoption of damage-only accidents, professionals were looking for a solution which could be the 2-lane design safer to operate. The reconstruction into one lane roundabout was chosen more frequently for resolving conflicts at two-lane exits. However, where the need was a greater capacity, the solution was a spiral 2-lane design. This was followed by the Dutch turbo roundabout, which was an upgraded version of spiral roundabout. A variety of designs and the geometric parameters are clearly defined by design standards nowadays. Turbo roundabouts are special junctions, where different traffic flows are physically separated from each other, which means less conflict points, it causes a good level of safety.
Témakör: Városi közlekedés
Abstract: Forest roads covered with asphalt pavement represent the basis of the forest opening up networks in Hungary. If properly maintained, asphalt pavements offer a high level of service. While traffic load of forest road networks have grown, expenses on their maintenance remained lower then required in the last three decades. As a result, this roads are in poor condition, generally. Renovation projects demand the knowledge of the roads’ bearing capacity. Bearing capacity measurements of roads traditionally were carried out using the Benkelmann beam. The Benkelman beam measurements provide the maximum vertical deflection of the pavement under 50 kN of wheel load. Nowadays the bearing capacity of public roads are measured with falling weight deflectometers. Falling weight deflectometer measurements provide the full deflection basin. It is convenient to use these high precision instruments on forest roads, but their application is inefficient and costly. Researchers of the Department of Forest Opening Up developed a new method to measure the full deflection basin with the Benkelman beam. Besides the instrument improvement the authors developed a new method for the processing of the deflection basin data. This paper introduces the results of a comparison between the deflection basins measured with the Advanced Benkalman Beam Apparatus and basins measured with the KUAB falling weight deflectometer.
Kulcsszavak: behajlásmérés, Benkelman-gerenda, nehéz ejtősúlyos behajlásmérés, teherbírás
Abstract: The long term utility of pavement structures is basically affected by the supporting subgrade. This effect is well-known among the civil engineers, however, there are relatively few methods applied in practice to express its extent in numbers. As the subgrade is one of the most sensitive bearing structures that is sensitive to environmental (meteorological) impacts and changes, a procedure adoptable in practice was presented in the first part also mentioning the possibility of damage summary being aware of the impact distribution and the application of those for simulation. In the second part critique is developed concerning the measuring technology of the metrological and physical contents applied in practice and the set of devices is presented, which shows the advantages and the possibilities of application of the devices working by seismic principal with especial regard to the application of deflection values measured out of the axle of the load. The third part is about the effects of the disposition of the stiffness of soil material properties and the volume change resulting partly in cyclical loads, the possible increase of resistance and a possibility of a relatively simple measuring method with which the behaviour of the completed or the working subgrade can be judged from the point of view of the potential longitudinal and transversal transformation.
Kulcsszavak: behajlási teknő paraméterek, egyenértékű felületi modulus, IRI (international roughness index), merevség, teherbíróképesség