Analysis of the application of waste and recycled materials for the production of pervious concrete pavements

У дисертацији су анализиране мешавине за израду порозног бетонског коловоза. Пројектовано је укупно 12 различитих врста мешавина. За справљање бетонских мешавина коришћене су фракције природног и рециклираног агрегата. Електрофилтерски пепео, који је отпадни материјал из термоелектрана, коришћен је као минерални додатак, којим је замењен део цемента. Справљено је шест мешавина са рециклираним агрегатом и шест мешавина са природним агрегатом. Лабораторијска испитивања су обухватила испитивање чврстоће при притиску бетона након: 7, 28, 56 и 84 дана, чврстоће при савијању (након 28, 56 и 84 дана), модул еластичности (статички и динамички), отпорност према хабању, коефицијент водопропустљивости и порозност. Добијени резултати потврдили су постављене хипотезе да је са рециклираним агрегатом и електрофилтерским пепелом могуће пројектовати и извести порозни бетонски коловоз.U disertaciji su analizirane mešavine za izradu poroznog betonskog kolovoza. Projektovano je ukupno 12 različitih vrsta mešavina. Za spravljanje betonskih mešavina korišćene su frakcije prirodnog i recikliranog agregata. Elektrofilterski pepeo, koji je otpadni materijal iz termoelektrana, korišćen je kao mineralni dodatak, kojim je zamenjen deo cementa. Spravljeno je šest mešavina sa recikliranim agregatom i šest mešavina sa prirodnim agregatom. Laboratorijska ispitivanja su obuhvatila ispitivanje čvrstoće pri pritisku betona nakon: 7, 28, 56 i 84 dana, čvrstoće pri savijanju (nakon 28, 56 i 84 dana), modul elastičnosti (statički i dinamički), otpornost prema habanju, koeficijent vodopropustljivosti i poroznost. Dobijeni rezultati potvrdili su postavljene hipoteze da je sa recikliranim agregatom i elektrofilterskim pepelom moguće projektovati i izvesti porozni betonski kolovoz.In the dissertation, mixtures for the production of pervious concrete pavements are analyzed. The project has a total of 12 different types of mixtures. For the preparation of concrete mixtures, the fractions of natural and recycled aggregates were used. Fly ash, which is a waste material from thermal power plants, was used as a mineral supplement, which replaced a part of cement. Six mixtures with a recycled aggregate and six mixtures with a natural aggregate were collected. Laboratory tests included: compressive strength after 7, 28, 56 and 84 days, felxural strength (after 28, 56 and 84 days), modulus of elasticity (static and dynamic), abrasion, permeability and porosity. The obtained results confirmed the hypotheses that it is possible to design and execute a previous concrete pavement with a recycled aggregate and fly ash

Expert project analyses in the process of road maintenance management

Za potrebe učinkovitog gospodarenja održavanjem cestovne mreže neophodno je raspolagati s ažurnom informacijskom osnovom i odgovarajućim modelom za odlučivanje. U radu se daje prikaz metodološkog postupka za ekspertne projektne analize za radove na održavanju i poboljšanju cesta uz korišćenje Baze Cestovnih Podataka (BCP) i primjenu HDM-4 modela. Postupak je uspješno primjenjen i prihvaćen u apliciranju zahtjeva za financiranje radova na održavanju i poboljšanju cestovne mreže od strane međunarodnih financijskih institucija (Svjetska Banka, EIB i EBRD) tijekom 2012-e godine.An updated information system, and an appropriate decision making model, must be put in place for an efficient road maintenance management. A methodological procedure for expert project-level analyses of road maintenance and improvement activities, based on the Road Data Base (RDB) and the HDM-4 model, is presented in the paper. The procedure was successfully applied and accepted in 2012, in the scope of application for funding of road network maintenance and improvement by international financing institutions (World, Bank, EIB and EBRD)

A measurement of roughness as indicator of road network condition – case study Serbia

Prethodna istraživanja su utvrdila da je mjerenje uzdužne hrapavosti kolnika izraženo kroz međunarodni indeks hrapavosti (International Roughness Index - IRI) jedan od najvažnijih pokazatelja za ukupnu ocjenu stanja cestovne mreže. U isto vrijeme IRI predstavlja ključni okidač za planiranje i primjenu različitih radova održavanja cesta kao što su sanacije ili rekonstrukcije kolnika. U radu se razmatraju postojeće metode za mjerenje hrapavosti kolnika i ocjenu stanja cestovne mreže u Republici Srbiji u ukupnoj dužini od 13 191,34 km.Earlier researches have established that the measurement of pavement longitudinal roughness expressed through International Roughness Index (IRI) is one of the most important indicators for overall evaluation of road network condition. At the same time IRI presents the key trigger for planning and applying the different road maintenance works like pavement rehabilitation or reconstruction. This paper examines the existing methods for measurement of pavement roughness and evaluation of the road network condition in the Republic of Serbia in total length of 13 191,34 km

Outputand perfomance based road maintenance contracting – case study Serbia

U radu se opisuju glavne karakteristike ugovora o održavanju i popravku cesta prema Output and Performance-Based Contracting for Roads (OPBC). Daje se pregled iskustava u primjeni takvih ugovora. Agencije za održavanje cesta koje su prihvatile OPBC pristup uštedjele su od 10 % do 40 % u cijeni radova u usporedbi s radovima ugovorenim po tradicionalnoj metodi. U razdoblju od 2004. do 2008. u Srbiji je bio primijenjen način ugovaranja prema Output Performance-based Maintenance Contract (OPBC) za pilot projekt u okviru Transport Rehabilitation Project-a financiranog od Svjetske banke. Prikazani su glavni rezultati i zaključci.The paper describes the main features of contract work for road maintenance and improvement under the Output and Performance-Based Contracting for Roads (OPBC). Experiences in the application of such contracts for the roads are reviewed. Road agencies that have adopted an OPBC approach have achieved cost savings from 10 % to 40 % compared to traditional method-based contracts. During the period 2004 ÷ 2008 Serbia implemented the Output Performance-based Maintenance Contract (OPBC) for routine road maintenance pilot project within Transport Rehabilitation Project financed by World Bank. The main results and conclusions are presented

The Influence of Temperature Changes on Concrete Pavement

The paper deals with the influence of temperature changes on concrete pavement. Due to differences in temperature on the upper and the lower surface of a concrete slab, the bending stress is created, resulting in concrete slab deformation. During the process of heating, the difference in temperature between the upper and the lower surface of pavement is created as a result of heat conduction. The upper surface has a tendency to expand (tense), whereas the lower one does not alter its dimensions, which results in generating the bending stress. Concrete pavement is most commonly placed in zones with extremely heavy traffic load as well as at bus stops. The analysis was carried out at bus stops in the city of Novi Sad for three different types of slab thickness. The thickness of slabs was 20, 22 and 24 cm. The testing was conducted in the longitudinal and transverse direction of the concrete pavement, both in the middle and on the edge of a slab. During the analysis of results, a conclusion was drawn that the concrete slabs were of different dimensions and thickness, and that they were placed on different subgrade reactions. The maximum values of stress were recorded in the middle of a concrete slab, in slabs whose thickness amounted to 24 cm, while the minimum stresses were identified in slabs which were 20 cm thick. The paper presents the stresses of concrete slabs, caused by changes in temperature, which depend on the subgrade reaction and dimensions of concrete slabs

Physicomechanical properties of fly ash applicable in road construction

U radu je prikazano eksperimentalno istraživanje fizikalno-mehaničkih svojstava letećeg pepela i stabiliziranog pepela s dodatkom vapna i cementa primjenjivog za gradnju cesta. Vezivo je dodavano sa 2, 4 i 6 % u odnosu na ukupnu količinu letećeg pepela. Nakon izvršenih ispitivanja uočljivo je da uzorci pepela bez dodataka i s dodatkom veziva mogu koristiti za izradu temeljnog tla, nasipa i posteljice, dok za izradu nosivih slojeva nisu preporučljivi. Istraživanje se temelji na korištenju letećeg pepela za izgradnju cesta, odnosno kao zamjena prirodnim materijalima u građevinarstvu, pri čemu se štede prirodni resursi čije su rezerve ograničene.An experimental research of physicomechanical properties of fly ash and ash stabilized with lime and cement, as used in road construction, is presented in the paper. The binder was added in the proportion of 2, 4 and 6 % of the total quantity of fly ash. The testing revealed that ash samples with and without binder can be used for improvement of foundation soil and for construction of embankments and subgrade layers, but are not recommended for construction of subbase and base courses. The research is based on the use of fly ash for road construction, i.e. as a substitute for natural materials in construction industry, as this use would save natural resources whose reserves are limited

Methods for determining increased maintenance of pavement structures in the city

U radu je dan prikaz metode za prikupljanje podataka, a nakon toga i metode za određivanje pojačanog održavanja kolničkih konstrukcija u gradu. Za analizu su uzeta tri tipa gradske cestovne mreže, odnosno analizirane su kolničke konstrukcije za gradsku magistralu, gradsku prometnicu i glavnu ulicu. Korišteni su podaci koji su uzeti na terenu i dobiveni rezultati laboratorijskih ispitivanja. Nakon prikazanih svih prikupljenih podataka, dano je tehničko rješenje kolničke konstrukcije, a potom se dolazi do zaključka da treba izvesti pojačano održavanje, odnosno rekonstrukciju sva tri tipa kolničkih konstrukcija.A data collection method, and methods for determining increased maintenance of pavement structures in the city, are presented in the paper. Three types of urban road network were selected for the analysis, i.e. pavement structures for the urban main road, urban road, and collection street were analysed. On-site data and laboratory test results were used in the study. After presentation of all data collected for the analysis, a technical solution for pavement structure is given, and it is concluded that an increased maintenance, i.e. full-scope rehabilitation, must be made for all three pavement structure types

Analysis of the hydraulic binder use for base strengthening in pavement constructions

The paper presents the application of cement stabilization in the world and in our country. In addition to the literature review, basic physical - mechanical tests of the pavement base without the use of hydraulic binder and with the use of hydraulic binder with different percentages of participation (3, 5, and 7%) were given. The hydraulic binder of the manufacturer LaFarge HRB 12.5 was used as a binder, and the material on which this binder was tested is a clay material taken from Subotica. Using this binder, it was concluded that any percentage of binder leads to significant improvement of the placenta and thus improves the load-bearing capacity of the pavement structurePublishe

Properties of fly ash and slag from power plants

This paper describes the physical, chemical and mineral properties of ash and slag, which were taken from thermal power plants Nikola Tesla A, Nikola Tesla B, Kostolac A and Kostolac B. The knowledge of the mineralogical material composition is important because the type of minerals directly determines the properties of the fly ash and slag and their possible application. Laboratory tests showed that ash and slag samples consist of the following minerals: amorphous materials, quartz, feldspar, mullite, melilite, cristobalite, haematite and calcite. The fly ash and slag chemical properties are the most important indicators in the evaluation of their suitability as a building material. The ash and slag chemical composition is composed of the following chemical components: SiO2, Al2O3, Fe2O3, CaO, MgO, SO3, S, Na2O and K2O. Results of laboratory tests show that fly ash and slag have variable chemical, mineralogical and physical properties that are dependent on the natural composition, quality of coal from basin, the manner of combustion and place of ash deposition