bluuebunny/crossref_metadata_2025 huggingface dataset:
Determination of thermal parameters of hardening concrete by means of inverse problem solution
Authors: Knor Grzegorz , Glinicki Michał A. , Holnicki-Szulc Jan
Published: July 2024

The paper presents the procedure of determining the thermophysical properties of concrete: heat of hardening, thermal conductivity and specific heat, which is based on point temperature measurements in a cylindrical mold and the numerical solution of the inverse heat transfer problem. The procedure was tested on concrete materials made with high-calcium fly ashes. The obtained results show good agreement with the real values of individual parameters and can be used to determine the temperature field in the object of any complex shape.
Pozzolanic and hydraulic activity of calcareous fly ash
Authors: Giergiczny Zbigniew , Garbacik Albin , Ostrowski Mikołaj
Published: July 2024

Usefulness of domestic calcareous fly ashes as pozzolanic and hydraulic constituents of cements and hydraulic binders is a subject of this paper. Test results of standard properties, activity indices of calcareous fly ashes and physical and mechanical properties of cements with this kind of fly ash are presented. Factors which might exerted an influence on hydration and hardening processes of cements with calcareous fly ashes form Bełchatow Power Station were analyzed. Beneficial results of calcareous fly ash activity were discussed regarding phase composition and morphology. The function of glassy phase in hydration and hardening processes of fly ashes as well as cements and binders with this constituent was emphasized.
Microstructure analysis of concrete modified with addition of calcareous fly ash
Authors: Glinicki Michał A. , Krzywobłocka-Laurów Róża , Ranachowski Zbigniew , Dąbrowski Mariusz , Wołowicz Jolanta
Published: July 2024

The investigation of concrete microstructure and phase composition was performed on concrete specimens produced with and without calcareous fly ash obtained from Bełchatów Power Station. The used calcareous fly ash (designated “W”) was either unprocessed or ground to assumed specific surface and added to concrete mix to substitute 30% of the binder by weight. The following testing methods were used in this research: scanning electron microscopy, differential thermal analysis (DTA) and multiple microindentation. The characteristic features of the investigated microstructures are discussed and the effect of calcareous fly ash on the content of non-evaporable water and portlandite in cement matrix is analysed. The results of microindentation and compressive strength testing were used as the basis for evaluation of the efficiency of calcareous fly ash added to concrete mix.
The effect of calcareous fly ash on selected properties of new generation of concrete
Authors: Gołaszewski Jacek , Ponikiewski Tomasz
Published: July 2024

The analysis of the effect of calcareous fly ash on selected properties of self-compacting and high performance self-compacting concretes is the subject of this paper. The investigation included the variable degree of grinding of calcareous fly ash and a different type of cement modified with calcareous fly ash. The results of tests on the SF class of flow and viscosity grade T500 of tested mixtures, as well as tests on concrete compressive strength (fcm,28, fcm,90), flexural strength (fcf,28, fcf,90), absorption tests and tests on water penetration depth are presented. Concrete mixture was modified using a variable volume fraction of calcareous fly ash as a type I and type II additive (10, 20 or 30%). The studies confirmed the possibility of using calcareous fly ash in self-compacting and high performance self-compacting concretes, while maintaining the assumed workability.
Evaluation of protective properties of concretes made of cements with calcareous fly ash with respect to reinforcing steel
Authors: Śliwka Andrzej , Domagała Katarzyna , Zybura Adam
Published: July 2024

The studies on the protective properties of concrete made of cements containing calcareous fly ash are presented in the paper. The aim of the studies carried out by electrochemical methods was to determine the susceptibility of reinforcing steel corrosion, protected by the analysed concretes, as well as to define the rate of reinforcement corrosion installed in the loaded and cracked samples, subjected additionally to the action of chloride solution. The obtained results were compared with the values of Portland cement concrete, considered as reference. The results showed that the addition of up to 50% calcareous fly ash do not reduce the protective properties of concretes with respect to reinforcing steel, while the use of fly ash together with blast furnace slag leads to the deterioration of reinforcement.
New analytical solution of flow and heat refraction problem in multilayer pavement
Authors: Graczyk Mirosław , Rafa Józef , Rafalski Leszek , Zofka Adam
Published: July 2024

The paper covers a new analytical solution of a flow and refraction problem in a multilayer pavement. The solution includes conditions of internal and external exchange as well as cyclic temperature and heat flux changes. Solution of a problem of heat conduction in a multilayer system showed a significant influence of coefficients introduced by the authors on the temperature and thermal stresses field in structure of a multilayer pavement. The coefficients were: diffusivity, thermal matching of layers and thermal refraction of layers. It was found that solar radiation is very important climatic factor acting directly on the upper layer of pavement, causing an increase in temperatures and creation of an additional temperature gradient in a multilayer pavement. It is shown that temperature field in a multilayer pavement depends significantly on geometry of layers structure, thermal characteristics of upper and lower layers expressed by Biot and Fourier numbers, colour of a surface course, humidity, velocity of wind etc., which are expressed by value of an external heat transfer coefficient. Moreover, an original example of analysis of an influence of pavement layer and subgrade parameters as well as climatic conditions on the temperature field in three different pavement structures, is shown. Results of the presented analysis can be directly applied in roads and airstrips pavements design.
Assessment of load bearing capacity of reinforced concrete bridge on the base of NDT results
Authors: Topczewski Łukasz , Cieśla Juliusz
Published: July 2024

The article presents the process of assessment of load bearing capacity of the existing bridge as well as determination of scope and method of its renovation on the basis of complex non-destructive testing and material examinations. The assessment of load capacity of old bridges, used for decades, is usually difficult due to several reasons: inaccessible technical documentation, loss of the structure history, unknown regulations used during the bridge designing. Moreover, physical properties of materials have changed and structural damages appeared during use, what contributes to the overall process of structure deterioration. In such situation an advanced non-destructive methods of structural testing and material examinations are required to determine the type of the used materials, their properties as well as their arrangement inside a structure. In the example shown, the GPR and profometer methods are used in order to determine the amount of reinforcement inside the bridge slab and the impact-echo and pull-out methods were used for determination of its thickness and the concrete class.
Load capacity and serviceability conditions for footbridges made of fibre-reinforced polymer laminates
Authors: Chróścielewski Jacek , Klasztorny Marian , Nycz Daniel , Sobczyk Bartosz
Published: July 2024

The contribution is focused on derivation of the Ultimate Limit State (ULS) and Serviceability Limit State (SLS) design criteria for footbridges built of fibre-reinforced polymer matrix (FRP) laminates. The ULS design criterion is based on the design guidelines for above-ground, pressure, FRP composite tanks and the Tsai-Wu failure criterion, which is used to predict the onset of FRP laminates damage. The SLS criterion is based on vertical deflections and natural frequencies limitations of the analysed FRP footbridge. As a part of the research, a special design procedure is established for FRP footbridges design process, covering both the preliminary and detailed engineering calculations. As an illustrative example, the procedure is applied to glass-fibre reinforced vinylester laminate with 90°C heat deflection temperature and 50-year service life. A deflection-based serviceability limit state criterion is established using the same approach as that currently used in the design of steel footbridges. Moreover, the second serviceability limit state criterion is proposed. It limits the range of possible fundamental natural frequency of footbridge without any load and loaded with an additional mass 70 kg/m2 applied to simulate load created by moderate pedestrian traffic.
Rheological properties of road bitumen binders modified with SBS polymer and polyphosphoric acid
Authors: Sarnowski Michał
Published: July 2024

A commonly used method to improve the viscoelastic properties of road bitumens is polymer modification with styrene-butadiene-styrene (SBS). New binder modifiers are being searched for to provide a technically and economically justified alternative. A recent method of modification, which has been in use for over 15 years (mainly in the U.S.), is based on addition of polyphosphoric acid (PPA). The effect of modification with polyphosphoric acid is similar to that of oxidation, i.e. it increases the binder stiffness yet without compromising its low-temperature performance. The effect of modification with polyphosphoric acid has not been so far comprehensively tested in Poland. According to various reports from research projects carried out in different countries improvement of binder properties and durability of asphalt mixtures largely depends on the type of pure bitumen used. This paper describes the effect of PPA modifier on the rheological properties of a bitumen obtained from a Polish refinery.
Pandora - valuation method of social costs of road accidents in Poland
Authors: Jaździk-Osmólska Agata
Published: July 2024

The paper presents a valuation method of social costs of road accidents and collisions in Poland, which was developed in the Economic Division of Road and Bridge Research Institute. In addition to personal losses (expressed in physical victims of road accidents) and emotional losses (in relation to a victims' circle and their loved ones suffering mostly in the emotional way), the economic costs fall into a basic category of consequences of road occurrences. The high share of all these costs in the economy of countries (an average of over 2% of GDP), gives them the economic dimension of a problem. Moreover, the results of a detailed analysis of their structure convince that it is worth considering the process of road safety in a broader context, not just a transport one, but social as well. Dangers posed by road traffic and expressed as personal and emotional losses are still undervalued by a society and a governing body. That is the reason why the motorization education including the economic aspect can be effective: financial arguments appeal to the imagination of each homo economicus. From the operational level, unit costs of accidents in the form of the value of life and health of victims, are an essential element of the economic viability valuation of road projects, based on an analysis of social costs and benefits of road users. For this reason the choice of valuation methods for socio-economic costs of occurrences is essential and that is why it has been the subject of research in the field of transport economics for a long time.
Analysis of external costs of transport within the scope of emissions of air pollution and noise
Authors: Zawieska Jakub
Published: July 2024

The paper aims to present a review of the most important issues related to air pollution emissions from the transport sector and an accessible knowledge of their external costs assessment. The main categories of pollution are described, and a contribution of the transport sector to global and domestic emissions is analysed. Additionally, as a part of this paper, various threats and types of external costs related to those emissions are discussed. The paper also contains the review of methodologies for evaluation of emissions external costs for individual categories of pollution. Furthermore, it demonstrates available results of estimations concerning those costs performed over recent years in Europe.
Methodology for determining traffic volume for the analysis of roads efficiency
Authors: Spławińska Malwina
Published: July 2024

The present paper outlines the results of analyses of two hundred highest hourly volumes in a year, used for determining designed hourly volumes DHV to test road efficiency. Basing on them, three equations of the power function were elaborated. They enabled the assessment of traffic volume corresponding to a randomly chosen peak-hour in a year, depending on the value of annual average daily traffic AADT (below or above 25000 V/d), the share of heavy vehicles (below or above 30%), and the type of cross-section (1x2 or 1x4/2x2). In case of two-lane roads (1x2) the variation of direction distribution and per weekday with the highest hourly volumes in a year were analysed. As a result, it allowed for working out the methodology of estimating design hourly volume DHV, including a transition from values determined for road cross-section to individual road traffic directions. Finally, a calculation example, illustrating a practical method for making good use of obtained test results, was presented.
Impact of reinforcement layer material and thickness on deflections measured in the static and dynamic plate load tests
Authors: Krawczyk Bartłomiej , Mackiewicz Piotr
Published: July 2024

The bearing capacity and compaction values obtained in the plate load tests (the latter determined indirectly) often depend on the used test method: static - using static load test apparatus (VSS) or dynamic - using light weight deflectometer (LWD). Despite extensive comparative studies the correlation between two test methods still remains an issue. With the values obtained in the field tests and with the use of numerical calculations allowing for the impact of viscoplastic phenomena, the authors managed to demonstrate how big is the effect of not only the type of material, but also of the thicknesses of the reinforced subgrade layers on the discrepancy between the displacement values obtained with the two test methods in consideration. The behaviour of the subgrade material during the tests was verified using the finite element method. The share of elastic, plastic and creep strains in the total strain was determined for different layered systems and thicknesses.
Steel plate curvatures of soil-steel structures during construction and exploitation
Authors: Machelski Czesław
Published: July 2024

The paper analyses the deformation of cir- cumferential bands of shells made of corrugated metal sheets in soil-steel structures. A change of curvature in the crown of a shell is assumed as a measure of deformation. In the upper part of analysed objects, regardless of their cross-sectional geometry, e.g. arched or elliptical shaped, a section of shell with a constant radius of curvature R is nowadays designed. As a result of earth pressure, moving loads and the self-weight of metal sheets, the shape of this part is subjected to deformation with a noticeable deviation from the circular shape. The change of curvature radius is determined in the paper on the basis of three coordinates of measuring points that form a triangle inscribed in a circle. Every (asymmetrical) position of the measuring points is taken into account. A system of three such points is transformed into a form of an equilateral triangle, and thus the radius of curvature is determined. Based on the change of curvature formulated during the construction and exploitation of soil-steel structures, the bending moments and normal stresses in the shell crown can be estimated and therefore a safety evaluation of the objects is possible.
Deformation of buried corrugated metal box structure under railway load
Authors: Machelski Czesław , Korusiewicz Leszek
Published: July 2024

The deformations of the circumferential section of a railway buried corrugated metal structure’s shell under the operational load are analysed in this paper. Considering its geometry, the structure belongs to box structures. The deflections and stresses (determined from unit strains) in selected points of the shell were adopted as the measure of the deformations. The quantities were measured using inductive sensors and electrical resistance strain gauges. The moving load procedure was used in the tests whereby the results are presented in the form of continuous quantity-load location functions. The analyses show close similarity between the displacements of the tested structure and those of other arch structures (e.g. brick vaults). As the vehicle travels over the box structure, the strain (normal stress) in the structure alternates (changes its value and sign as a function of vehicle location), which is a characteristic feature of such structures, but the recorded displacement and stress values are very low in comparison with the ones generated during construction.
Analysis of climatic zones in Poland with regard to asphalt performance grading
Authors: Pszczoła Marek , Ryś Dawid , Jaskuła Piotr
Published: July 2024

Towards the end of the last century a new system of bitumen grading was developed and implemented as part of the American Strategic Highway Research Program (SHRP). Its aim was to better adjust the testing methods and requirements for road bitumens to the actual conditions in which those bitumens serve in road pavements. Currently in Poland, similarly as in the other EU countries, road bitumens are tested and classified with regard to mainly the penetration value determined at the temperature of 25°C. It should be noted that this classification is not correlated with the climatic conditions in which the bitumens are to serve in the road pavement. This paper presents the results of analyses concerning the determination of the temperatures at which bituminous binders serve in the Polish climatic conditions. A division of the area of Poland into climatic zones depending on the required performance grades (PGs) determined for bitumens on the basis of climatic data from 61 meteorological stations for a period of minimum 20 years is presented. It is proposed to select bitumens depending on the climatic zone in Poland, taking into account the proper probability level which follows from the road class.
Review of analytical-empirical methods for determining stiffness moduli of asphalt mixtures
Authors: Słowik Mieczysław , Bartkowiak Mikołaj
Published: July 2024

The paper outlines and elaborates models for determining stiffness moduli of asphalt mixtures. Some original patterns taken from source articles and alternative forms of formulas after their adaptation to the SI system of units were introduced. Various laboratory methods for determining the stiffness modulus including methods for fixing that quantity of a given model were discussed. All of input data needed for determining the stiffness modulus with the use of selected models and basic information concerning preparations of samples for determining that quantity through laboratory methods were presented. Attention was turned to errors which can be made while making use of analytical-empirical models. The values of stiffness moduli determined with the use of analytical-empirical models were also compared with their equivalents of experimental tests described in the literature.
Tests and calculations of structural element of temporary bridges
Authors: Ganyukov Aleksandr , Kadyrov Adil , Balabekova Kyrmyzy , Kurmasheva Bakyt
Published: July 2024

The new concept of mobile temporary bridge overcrossing intended for a reduction of traffic jams is presented in the paper. After discussing the bridge structure details, the optimum length of the module of the bridge overcrossing is determined and then calculation of the orthotropic plate of the bridge carriageway and its supporting structure are presented. In the calculations elements of the mathematical analysis, method of finite elements FEM and method of finite differences FDM as well as analytical displacement method were applied. Reliability of results is confirmed by coincidence of deflections obtained by both, FEM and FDM, methods. The solution matrix of the FDM obtained in this work allows to calculate any plate with wide variety of its geometrical dimensions, and also for different parameters of the plate and reinforcing elements flexural stiffnesses. The analysis of the bridge overcrossing spatial frame is performed by precise method of displacement taking into account the bending and torsion of its elements.
Resistance of selected aggregates from igneous rocks to alkali-silica reaction: verification
Authors: Jóźwiak-Niedźwiedzka Daria , Antolik Aneta , Dziedzic Kinga , Glinicki Michał A. , Gibas Karolina
Published: July 2024

The paper presents investigations into the reactivity of aggregates from igneous rock, carried out in accordance with the procedures contained in the GDDKiA General Technical Specification "Concrete pavements". The aim of the investigations was evaluation of the suitability of the aggregates for road structures and pavements built using cement based concrete technology. Aggregates produced from extrusive rocks (basalt, melaphyre and porphyry) and from intrusive rocks (granite and gabbro) were analysed. The mineral composition of the aggregates was evaluated with regard to their reactive SiO2 content. Expansion tests on mortar bar and concrete prism specimens with analysed aggregates and a microscopic analysis of the alkali-aggregate reaction products were carried out. A considerable amount of reactive minerals: chalcedony, tridymite and microcrystalline quartz and volcanic glass were found in the grains of the porphyry and melaphyre aggregates. On the basis of the conducted investigations the two aggregates made of igneous rocks (melaphyre and porphyry) were classified into category R1 (moderately reactive). The basalt aggregate, the granite aggregate and the gabbro aggregate were assigned to category R0 (non-reactive).
Assessment criteria of the recycled aggregate cement bound bases
Authors: Krawczyk Bartłomiej , Szydło Antoni , Mackiewicz Piotr , Dobrucki Dariusz
Published: July 2024

The paper deals with investigations into the possibility of using crushed concrete reclaimed from road pavements to produce new cement bound mixtures for roadbase courses. From the economic and technical points of view crushed concrete waste constitutes an alternative source of aggregates which can replace natural aggregates in cement bound mixtures. First, recycled concrete aggregate was tested with regard to the current requirements which aggregates for cement bound roadbases must meet. Then, the strength and frost resistance tests were carried out on cement bound mixtures based on recycled concrete aggregates and natural aggregates. The possibilities and limitations of the use of recycled concrete aggregate for cement bound roadbase courses were examined. The results of the performed tests proved that recycled concrete aggregate, even though it does not meet the water absorption and frost resistance requirements, can be used to build durable cement bound roadbases.
Testing the concentration of trace metals in soils near roads with varied traffic intensity
Authors: Ćwiąkała Michał , Korzeniowska Joanna , Kraszewski Cezary , Rafalski Leszek
Published: July 2024

Motor transport affects the state of the natural environment and results in the accumulation of trace metals in roadside soils. The trace metal concentrations in roadside soils depend mainly on the distance from the road and the traffic intensity. The aim of the investigations was to determine the range of the environmental impact of the (Cracow-Zakopane) transport route and the effect of traffic intensity on the concentrations of trace metals in the soil. Three road sections differing in their traffic intensity were selected for this purpose. The concentrations of Cr, Cu, Ni, Pb and Zn in soil samples taken from a depth of 0-30 cm at a distance of 5, 10, 50 and 100 metres from the road were spectrophotometrically determined. The metal concentrations in the surroundings of the Cracow-Myślenice road carrying heavy traffic were found to be several times higher than the ones in the soils near the Łopuszna-Dursztyn local road with low traffic intensity. The largest differences in trace metal concentrations in the soils were found for nickel (four times higher concentrations along the Cracow-Myślenice road) at all the considered distances and for copper (three times higher) at the distances of 5 and 10 metres. In comparison with the reference areas, in the vicinity of the investigated roads the concentrations of Cr, Cu, Ni, Pb and Zn in the soil were found to be elevated. The fact that the concentrations of the trace metals decrease with increasing distance from the road's edge clearly indicates the traffic-related origin of the contaminants.
Design and evaluation of stone matrix asphalt using stiffer grade crumb rubber modified bitumen
Authors: Kumar Gajendra , Sahoo Umesh C. , Rao K. Ramachandra , Bose Sunil
Published: July 2024

Stone Matrix Asphalt (SMA) is primarily used as a surfacing layer material since it is found to perform well under heavy traffic conditions and at the same time is more cost-effective when compared to the conventional dense graded mixes. An attempt has been made in this study to incorporate a stiffer grade crumb rubber modified bitumen (CRMB) for design of SMA. Extensive laboratory studies on mixes prepared with different modified binders and normal binders (with fibers) were conducted. The results obtained indicate that SMA designed using CRMB-70 and CRMB-80 performs well under heavy traffic conditions and at the same time without significant drain-down. Further, CRMB-80 is found to be suitable at high temperatures since it yields a very low accumulated strain and is thus recommended for designing rut resistant durable mixes. In addition, CRMB-80 yields the least rut depth of 4.5 mm even after 20,000 load repetitions.
Assessment of the effect of concrete slab geometrical parameters on the distribution of stresses in the road pavement structure
Authors: Zbiciak Artur , Graczyk Mirosław , Józefiak Kazimierz , Brzeziński Karol , Michalczyk Rafał
Published: July 2024

The analysis of the state of stress prevailing in a concrete overlay slab made on an existing flexible pavement structure is presented. The concrete overlay (whitetopping) was made on the using laid over a package of pavement layers of known stiffness. The effect of loads generated by the temperature gradient and vehicle wheels loads was examined. Several whitetopping variants differing in the structural geometry were analysed. The calculations were carried out using the finite element method. A change in the length of slab can lead to a reduction in pavement building costs. A greater slab length results in a smaller number of transverse joints per kilometre and consequently, in lower labour intensity and fewer dowels used. But the maximum stresses generated by thermal and service loads increase as the length of this structural component is increased. Therefore it may be necessary to increase the thickness of the slab to ensure its proper fatigue life. Using the proposed analytical method one can optimize concrete pavement rehabilitation costs. Because of the complexity of the problem an individual approach to the particular cases must be adopted in order to find an optimal solution.
Determinations of critical gap and follow-up time at roundabouts in Jordan
Authors: Hazim Nabil , Bazlamit Subhi M. , Salem Zaydoun Abu , Alghazawi Omar , Odeh Issam
Published: July 2024

Critical gap and follow-up times are two important fundamental traffic parameters used in the design and operational analysis of roundabouts and un-signalized intersections. Moreover, they are used to assess capacity and level of service at minor roads. In Jordan, roundabouts are used extensively, and therefore, there is a need to conduct studies on follow-up and critical gap time. The driver behaviour in Jordan can be described as aggressive in terms of their choice of follow-up headway at roundabouts. In this study, the roundabouts were located in mountainous terrain which allowed the collection of critical gap observations for approach slopes ranging from 6% up to 8%. The critical gap and follow-up times were recorded and analyzed. This research also identified other factors affecting critical gap, lag and follow-up times such as geometry of roundabout, slope of the approach, culture and behaviour of drivers. This research also proposes a significant relationship between approach slope at roundabouts and the observed gap. This relationship may be incorporated in the estimation of capacity and level of service determination at roundabouts. The results of this study should assist highway and traffic designers in the design and the performance evaluation of roundabouts.
Innovative technique for road slope stabilisation
Authors: Broda Jan , Mitka Andrzej , Gawłowski Andrzej
Published: July 2024

The paper describes an innovative method for stabilisation and greening of newly formed road slopes. Meandrically arranged thick ropes made from textile waste covered with soil mixed with randomly distributed wool and polyester fibres were applied for stabilisation. The ropes were installed on the slope in autumn. Hydroseeding was performed the following spring. Behaviour of the slope during several months was regularly monitored. In the first period – during autumn and winter – the ropes in combination with fibre-reinforced soil reduced the danger of local landslides and soil erosion. After hydroseeding the system provided water supply needed for seed germination. During grass growth the fertilising effect of nitrogen compounds released as a result of wool biodegradation was revealed. Finally, a stable slope covered with high grass grown in a relatively short time was achieved.
Traffic simulation at unsignalized intersection in case of congestion on major street caused by an adjacent traffic signal
Authors: Gasz Krzysztof
Published: July 2024

Unsignalized intersections belong to the most common ways of traffic management at intersections. The capacity of the minor entries depends on many factors. One of them is the traffic flow pattern on the major street. In the case of slow-moving queue of vehicles on the main street caused by a downstream traffic signal, the capacity of movements on the minor street joining the queue of vehicles on the main street is significantly reduced. The surveys of traffic parameters were performed in three Polish cities: Wroclaw, Opole, and Krakow. On the basis of these studies, a simulation model representing the traffic conditions at such an intersection was developed. The influence of pedestrian traffic and the number of storage spaces in the median on the possibility of vehicles from the minor entries joining the queue of vehicles on the main street was examined.
Wpływ składu i właściwości mastyksu na odporność asfaltu lanego na deformacje trwałe
Authors: Kołodziej Krzysztof , Bichajło Lesław , Siwowski Tomasz
Published: July 2024

Mastyks asfaltowy ma duży wpływ na właściwości mieszanki mineralno-asfaltowej. O jego cechach decydują nie tylko właściwości poszczególnych składników, ale także wzajemne proporcje między nimi – głównie stosunek wypełniacz/lepiszcze. Do oceny mastyksu można stosować te same metody badań, co do oceny asfaltów drogowych, traktując go jako lepiszcze o bardzo dużej lepkości. Wyniki badań mogą posłużyć do wstępnego projektowania składu mieszanki asfaltu lanego, zwłaszcza w kontekście trwałości nawierzchni na obiektach mostowych, gdzie asfalt lany stanowi warstwę ochronną izolacji. W artykule przedstawiono wyniki badań ciągliwości mastyksu i odporności na deformacje trwałe asfaltu lanego, zawierających asfalt drogowy 35/50 zmodyfikowany dodatkiem asfaltu naturalnego Trinidad Epuré. Celem przeprowadzonych badań było ustalenie wpływu stosunku wypełniacz/lepiszcze oraz dodatku asfaltu naturalnego na umowną energię rozciągania w badaniu ciągliwości, a także określenie korelacji pomiędzy właściwościami mastyksu zawierającego zmodyfikowane lepiszcze a cechami mieszanki asfaltu lanego.
Diagnostyka przepuszczalności powietrza przez beton w przyczółkach wiaduktu w Płocku
Authors: Kubissa Wojciech , Dobaczewska Wioletta
Published: July 2024

Trwałość żelbetowych konstrukcji inżynierskich jest związana z odpornością otuliny zbrojenia na wnikanie agresywnych mediów ciekłych i gazów. Zgodnie z zaleceniami Eurokodu, grubość warstwy otuliny powinna być dostosowana do agresywności środowiska. Podejmuje się próby wykorzystania pomiarów przepuszczalności powietrza przez beton do oceny szczelności betonu w warstwie otuliny, aby wykryć ewentualne niedoskonałości wykonawcze. W artykule zaprezentowano wyniki badania przepuszczalności powietrza metodą Torrenta wykonane na przyczółkach drogowego obiektu inżynierskiego zbudowanego w Płocku. Przyczółki wykonano z betonu napowietrzonego klasy wytrzymałości C35/45, zaprojektowanego do klasy ekspozycji XC4, XD3, XF2. Kontrolę przepuszczalności powietrza przez beton przeprowadzono zgodnie ze szwajcarską normą SIA 262/1 w celu weryfikacji jakości wbudowanego betonu. Pomiary przepuszczalności powietrza wykonano również na formowanych próbkach kontrolnych w celach porównawczych. Wykazano przydatność metody, pozwalającej w sposób nieniszczący zweryfikować jednorodność otuliny w konstrukcji żelbetowej.
Zasady przyjmowania obciążeń przy sprawdzaniu nośności zabytkowych mostów i wiaduktów kolejowych
Authors: Rymsza Janusz , Rakoczy Anna M.
Published: July 2024

Zgodnie z polskim Prawem Budowlanym każdy obiekt, w tym również wpisany do rejestru zabytków, powinien zapewniać bezpieczeństwo użytkowania poprzez utrzymanie odpowiedniego stanu technicznego w przewidywanym okresie eksploatacji. Niestety przepisy prawne nie są jednoznaczne, w związku z czym te same modele obciążeń, zwłaszcza oddzia- ływań innych niż pionowe, stosuje się do nowych konstrukcji, które mają powstać i będą eksploatowane przez co najmniej 100 lat oraz do obiektów istniejący, w tym takich eksploatowanych od 100 lat, które Zarządca ma zamiar dalej bezpiecznie eksploatować przez kolejne np. 50 lat. Takie podejście jest sprzeczne z zasadami wiedzy technicznej, o których mowa w polskim Prawie Budowlanym, gdyż wartość większości „innych” obciążeń i oddziaływań przyjmowa- nych zgodnie z normą projektową wynika bezpośrednio z piono- wego obciążenia eksploatacyjnego. W artykule zaproponowano wartości charakterystyczne oddziaływań i częściowe współczynniki bezpieczeństwa, które powinny być używane do oceny istniejących mostów i wiaduktów kolejowych, zwłaszcza wpisanych do rejestru zabytków.
Efektywność napraw weekendowych ulic Warszawy na podstawie parametrów czaszy ugięć
Authors: Maliszewska Dominika , Maliszewski Maciej , Rembelski Rafał
Published: July 2024

W artykule przedstawiono ocenę efektywności rozwiązań wdrożonych z zastosowaniem technologii weekendowych remontów opracowanej przez Instytut Badawczy Dróg i Mostów dla Zarządu Dróg Miejskich w Warszawie. Głównym celem badawczym była weryfikacja przyjętych rozwiązań projektowych. Technologia remontu ewoluowała na przestrzeni lat, a zmiany były dokonywane na podstawie prowadzonych obserwacji. Pierwotnie podejście oparte było na przyjęciu jednego uniwersalnego rozwiązania, co miało swoje wady i zalety. Najnowsze podejście projektowe, zakładające zastosowanie metod obliczeniowych, wymaga weryfikacji. W tym celu po wykonaniu remontu przystąpiono do oceny diagnostycznej stanu nawierzchni i analizy uzyskanych parametrów kształtu czaszy ugięć. Przeprowadzono diagnostykę wybranych odcinków testowych przed remontem oraz po 3 latach od jego wykonania. W artykule przedstawiono wyniki tej weryfikacji. Planowane jest powtórzenie obserwacji w kolejnych latach eksploatacji nawierzchni w celu ponownej oceny rozwiązania projektowego oraz zaproponowania modeli prognostycznych dla stosowanej technologii remontu.
Evaluating the effect of aggregate size, cement content and water-cement ratio on performance of pervious concrete
Authors: Soltani Mehrtash , Moayedfar Reza , Yi Wen Polim Chan
Published: July 2024

Flash floods belong to the worst natural disasters and cause serious economic damage every year. Hence, use of pervious pavements in order to reduce surface runoff and allow the water to penetrate the soil is an important factor in flooding reduction. The main objective of the paper is to study the influence of various parameters, such as water-cement ratio (0.32, 0.35 and 0.38), cement content (350 kg/m3, 450 kg/m3 and 550 kg/m3) and aggregate size (2.83 mm, 5.66 mm and 8.00 mm), on the properties of pervious concrete in terms of water permeability, porosity and compressive strength. The obtained results revealed that aggregate size had the most significant effect on water permeability of pervious concrete. When a fixed water-cement ratio was considered, lower cement content provided higher porosity. Both in water permeability and porosity tests the highest values were observed for aggregate size of 8.00 mm. However, the results of the compressive strength test reached the highest value for the mixture with aggregate size of 5.66 mm, water-cement ratio of 0.35 and cement content of 550 kg/m3.
Szacowanie natężenia strumienia ruchu z wykorzystaniem pomiaru drgań powierzchni jezdni
Authors: Burdzik Rafał , Celiński Ireneusz
Published: July 2024

Pomiar parametrów ruchu drogowego w wybranym przekroju drogi zrealizowany może być z wykorzystaniem różnych technik. Pomiar może być wykonany w pasmie fal widzialnych, pasmie akustycznym lub z wykorzystaniem drgań. Większość drgań w pasie drogowym wywołują pojazdy poruszające się w strumieniu ruchu. W artykule przedstawiono sposób uproszczonego pomiaru natężenia strumienia ruchu z wykorzystaniem analizy drgań powierzchni jezdni wywoływanych przez pojazdy. Drgania pochodzące od poszczególnych pojazdów zależą od ich parametrów technicznych i stanu technicznego, jak również od rodzaju nawierzchni, klasy technicznej i stanu drogi. W artykule przedstawiono także próbę parametryzacji strumienia ruchu drogowego w wybranym przekroju drogi z wykorzystaniem metody analizy drgań nawierzchni. W tym celu użyto prototyp układu pomiarowego wyposażonego w akcelerometr ADLX335. Uzyskane w ten sposób wyniki pomiarów drgań nawierzchni zestawiono z danymi pomiarowymi z ręcznego rejestratora ruchu. Na podstawie otrzymanych wyników wykazano, że prezentowana metoda pozwala na szacowanie natężenia strumienia ruchu drogowego.
Wykorzystanie odpadów z tworzyw sztucznych do wytworzenia mieszanek związanych cementem
Authors: Krawczyk Bartłomiej , Mackiewicz Piotr , Dobrucki Dariusz
Published: July 2024

Tematem artykułu są badania nad możliwością wykorzystania materiałów pochodzących z recyklingu odpadów z tworzyw sztucznych. Materiały te zastosowano do wytworzenia mieszanek związanych cementem, przeznaczonych do warstw konstrukcji nawierzchni drogowej oraz podłoża ulepszonego. Przeprowadzono analizy na podstawie badań laboratoryjnych odpadów plastikowych, kruszywa oraz mieszanek związanych cementem. Badania obejmowały analizę składu ziarnowego i zagęszczalności, badania wytrzymałości na ściskanie (wczesnej – po 7 dniach; docelowej – po 28 dniach), badania mrozoodporności oraz badania kalifornijskiego wskaźnika nośności CBR. Wyniki badań odniesiono do obowiązujących krajowych wymagań technicznych. Wykazano możliwość stosowania materiałów z recyklingu odpadów plastikowych jako alternatywę dla klasycznie stosowanych materiałów.
Inicjacja warunków początkowych w modelu do analizy termicznej nawierzchni drogowej
Authors: Bilski Marcin , Górnaś Przemysław , Pożarycki Andrzej , Słowik Mieczysław , Mieczkowski Paweł
Published: July 2024

W pracy rozpatrzono możliwość inicjacji warunków początkowych w modelu do analizy termicznej nawierzchni drogowej w warunkach niestacjonarnego przepływu ciepła. Procedura wymaga przeprowadzenia obliczeń dla odpowiednio długiego czasu inicjacji do uzyskania początkowego rozkładu temperatury, który jest podstawą dalszych analiz przepływu energii cieplnej. Główną część pracy stanowi prezentacja eksperymentu numerycznego przeprowadzonego dla czterech konfiguracji wartości parametrów modelu przepływu energii cieplnej w ośrodku wielowarstwowym, jakim jest nawierzchnia. Każda konfiguracja parametrów odpowiada innej konstrukcji (dwa modele nawierzchni podatnej i dwa modele z warstwą z pianobetonu). Obliczenia przeprowadzono kolejno dla trzech różnych wartości amplitud sinusoidalnej funkcji zmiany temperatury w czasie, którą zde- finiowano jako warunek brzegowy w modelu nawierzchni. Uzupełnieniem eksperymentu numerycznego były obliczenia przeprowadzone dla jednej wybranej konfiguracji wartości parametrów modelu, w którym warunek brzegowy stanowiły wartości temperatury zarejestrowane czujnikiem wbudowanym w nawierzchnię. Na podstawie analizy uzyskanych wyników potwierdzono, że inicjacja warunków początkowych w równaniu przewodzenia ciepła jest możliwa w oparciu o analizę niestacjonarnego przepływu ciepła przedstawioną metodą.
Wykorzystanie destruktu asfaltowego jako kruszywo do mieszanek stabilizowanych spoiwem cementowym
Authors: Majer Stanisław , Budziński Bartosz
Published: July 2024

Destrukt asfaltowy może stanowić półprodukt w nowych mieszankach mineralno-asfaltowych jak i być wykorzystywany do mieszanek w technologii recyklingu na zimno. Pierwsza technologia jest właściwa w sytuacji kiedy destruktu jest jednorodny i pochodzi z nawierzchni o znanych lub możliwych do ustalenia parametrach. Druga technologia może być wykorzystana do przetwarzania starych nawierzchni asfaltowych, o zmiennych parametrach (różne warstwy z różnym lepiszczem), które nadal dominują na drogach lokalnych. Technologie na zimno z różnych względów nie zawsze mogą być zastosowane, np. w sytuacji, której przewidywany zakres prac jest niewielki. Alternatywą może być wykorzystania destruktu asfaltowego jako kruszywo do wykonania mieszanek stabilizowanych spoiwem. Autorzy przeprowadzili program badawczy, który miał na celu określenie parametrów mieszanek stabilizowanych spoiwem cementowym z wykorzystaniem destruktu. W badaniach określono takie cechy jak: gęstość, wytrzymałość na ściskanie w różnych temperaturach, wytrzymałość na rozciąganie przy rozłupywaniu, badanie stabilności wg Marshalla. Na podstawie przeprowadzonych badań, ustalono, że destrukt asfaltowy może zostać z powodzeniem wykorzystany jako kruszywo do produkcji mieszanki związanej spoiwem cementowym.
Lepiszcza asfaltowe modyfikowane dodatkiem miału gumowego ze zużytych opon samochodowych – badania i praktyka
Authors: Radziszewski Piotr , Sarnowski Michał , Pokorski Piotr
Published: July 2024

Recykling materiałów w budownictwie drogowym jest ważnym zagadnieniem w aspekcie ochrony środowiska oraz optymalizacji kosztów przedsięwzięć drogowych. W celu poprawienia właściwości lepiszczy asfaltowych coraz częściej stosuje się modyfikację dodatkami rozdrobnionej gumy ze zużytych opon samochodowych. Uzyskane w wyniku tej modyfikacji lepiszcza gumowo-asfaltowe charakteryzują się, podobnie jak polimeroasfalty, polepszonymi właściwościami lepkosprężystymi. Wykazują one jednak wyższą niż polimeroasfalty odporność na działanie niskiej temperatury. Wykorzystanie rozdrobnionej gumy z recyklingu opon samochodowych jest uzasadnione również ze względów ekologicznych i stanowi najlepszy sposób zagospodarowania odpadów gumowych. W artykule przedstawiona została analiza porównawcza właściwości lepkosprężystych lepiszczy gumowo-asfaltowych, która obejmowała ocenę właściwości w zakresie niskich, średnich i wysokich temperatur. Lepiszcza poddano badaniom w zakresie podstawowych wymagań przewidzianych dla asfaltów modyfikowanych, badaniom konsystencji w zakresie temperatur technologicznych oraz zaawansowanym badaniom reologicznym w reometrze dynamicznego ścinania oraz reometrze zginanej belki. Przedstawione zostały przykłady zastosowania lepiszczy gumowo-asfaltowych w realizacjach odcinków drogowych w Polsce. W podsumowaniu sformułowane zostały wnioski dotyczące możliwości modyfikacji, właściwości oraz zastosowania lepiszczy asfaltowych modyfikowanych dodatkiem miału gumowego ze zużytych opon samochodowych.
Plasticity of the proteasome-targeting signal Fat10 enhances substrate degradation
Authors: Negi Hitendra , Ravichandran Aravind , Dasgupta Pritha , Reddy Shridivya , Das Ranabir
Published: July 2024

The proteasome controls levels of most cellular proteins, and its activity is regulated under stress, quiescence, and inflammation. However, factors determining the proteasomal degradation rate remain poorly understood. Proteasome substrates are conjugated with small proteins (tags) like ubiquitin and Fat10 to target them to the proteasome. It is unclear if the structural plasticity of proteasome-targeting tags can influence substrate degradation. Fat10 is upregulated during inflammation, and its substrates undergo rapid proteasomal degradation. We report that the degradation rate of Fat10 substrates critically depends on the structural plasticity of Fat10. While the ubiquitin tag is recycled at the proteasome, Fat10 is degraded with the substrate. Our results suggest significantly lower thermodynamic stability and faster mechanical unfolding in Fat10 compared to ubiquitin. Long-range salt bridges are absent in the Fat10 structure, creating a plastic protein with partially unstructured regions suitable for proteasome engagement. Fat10 plasticity destabilizes substrates significantly and creates partially unstructured regions in the substrate to enhance degradation. NMR-relaxation-derived order parameters and temperature dependence of chemical shifts identify the Fat10-induced partially unstructured regions in the substrate, which correlated excellently to Fat10-substrate contacts, suggesting that the tag-substrate collision destabilizes the substrate. These results highlight a strong dependence of proteasomal degradation on the structural plasticity and thermodynamic properties of the proteasome-targeting tags.
Multi-day neuron tracking in high-density electrophysiology recordings using earth mover’s distance
Authors: Yuan Augustine Xiaoran , Colonell Jennifer , Lebedeva Anna , Okun Michael , Charles Adam S , Harris Timothy D
Published: July 2024

Accurate tracking of the same neurons across multiple days is crucial for studying changes in neuronal activity during learning and adaptation. Advances in high-density extracellular electrophysiology recording probes, such as Neuropixels, provide a promising avenue to accomplish this goal. Identifying the same neurons in multiple recordings is, however, complicated by non-rigid movement of the tissue relative to the recording sites (drift) and loss of signal from some neurons. Here, we propose a neuron tracking method that can identify the same cells independent of firing statistics, that are used by most existing methods. Our method is based on between-day non-rigid alignment of spike-sorted clusters. We verified the same cell identity in mice using measured visual receptive fields. This method succeeds on datasets separated from 1 to 47 days, with an 84% average recovery rate.