Offer preparation has always been a specific part of a building process which has significant impact on company business. Due to the fact that income greatly depends on offer’s precision and the ...balance between planned costs, both direct and overheads, and wished profit, it is necessary to prepare a precise offer within required time and available resources which are always insufficient. The paper presents a research of precision that can be achieved while using artificial intelligence for estimation of cost and duration in construction projects. Both artificial neural networks (ANNs) and support vector machines (SVM) are analysed and compared. The best SVM has shown higher precision, when estimating costs, with mean absolute percentage error (MAPE) of 7.06% compared to the most precise ANNs which has achieved precision of 25.38%. Estimation of works duration has proved to be more difficult. The best MAPEs were 22.77% and 26.26% for SVM and ANN, respectively.
This paper presents an analysis of the stabilization of different soil types using a hydraulic binder. A study was carried out on soils that can be classified into two groups: cohesive and ...non-cohesive soils. Clay soils of medium and low plasticity according to the USCS classification were used as cohesive materials, while the sandy material containing dust was considered as non-cohesive material. Samples were taken from fifteen locations in Vojvodina province, Serbia. A hydraulic binder was used as a binder based on cement and lime. The amounts of the binder were estimated at 3, 5, 7, and 9%. In order to determine the basic physical and mechanical characteristics of the specimens, the following tests were performed: unconfined compressive strength after 7 and 28 days, indirect tensile strength after 7 and 28 days, as well as the California Bearing Ratio. Based on the obtained results, it can be concluded that increasing the amount of binder results in an increase in the subgrade load-bearing capacity. However, it should be emphasized that the subgrade containing non-cohesive material had a lower growth in the load-bearing capacity than those with the cohesive material.
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 drawnthat 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.
The paper presents basic characteristics of pervious concrete and gives an overview of the most significant current researches in the world as well as the possibility of use of pervious concrete for ...road construction in Western Balkan's countries, like Serbia. The analysis of the recent researches is presented in the form of diagrams and correlations between physical and mechanical properties of pervious concrete. During the preparation of this type of concrete, it is observed that the aggregate has the most significant influence since it represents 70 to 80% of the total concrete volume, followed by the binder type, by the water-cement ratio and finally, by the additives within the concrete mixture. For the concrete preparation, recycled and light aggregates, with or without addition of small size aggregate (sand), were used. In general, all three aggregate types can be used for pervious concrete mixtures thus promoting the use of recycled aggregates and, by doing so, also supporting conservation of natural resources. Worldwide, pervious concrete is most often used for roads with light traffic, pedestrian and cycling path sand, therefore it could be used more often in Western Balkan countries for similar purposes.
Paper is a brief review of the research focused on formulation an numerical model for the concrete pavement which is made by the recycling material. For numerical modeling the finite element model ...(FEM) and the 3D finite element model were applied. The software EverFE 2.25, was used. The results of FEM analysis is in a chapter shape showing move value change, strees and deflections for all layers a construction road model. In the next phase of the research was provided by FEM software with appropriate general purpose non-linear models, which allows the analysis of the real behavior of solid pavement under load.
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.
Regression analysis is used to develop models for minimal daily pavement
surface temperature, using minimal daily air temperature, day of the year,
wind speed and solar radiation as predictors, based ...on data from Awbari,
Lybia,. Results were compared with existing SHRP and LTPP models. This paper
also presents the models to predict surface pavement temperature depending on
the days of the year using neural networks. Four annual periods are defined
and new models are formulated for each period. Models using neural networks
are formed on the basis of data gathered on the territory of the Republic of
Serbia and are valid for that territory.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Construction of Road Embankment with Waste Materials Vatin, Nikolay; Radović, Nebojša; Šešlija, Miloš
Applied Mechanics and Materials,
01/2015, Letnik:
725-726, Številka:
Innovative Technologies in Development of Construction Industry
Journal Article
Recenzirano
Fly ash represents a residue that occurs as a product of burning finely milled particles of coal in thermal power plants. The fly ash in the construction of embankments in road construction can be ...used with or without the addition of binders. For the construction of embankment from the ashes, aside embankments (trapezoid shape) are placed. Justification of this study is the fact that so huge amounts of this material are left aside, while there are great possibilities for using of natural materials in the construction of roads.
This paper examines the legal and practical aspects of Article 266 of the Serbian Criminal Code, which criminalizes the import, as well as illegal processing, disposal, and storage of hazardous ...materials in Serbia. The study explores the conceptual underpinnings of the law, emphasizing its role in safeguarding public health and environmental safety. It scrutinizes the application of Article 266, highlighting notable cases and enforcement strategies employed by Serbian judicial authorities, as well as a study cases related to problems of hazardous waste. The paper also delves into the inherent challenges in the legislation`s implementation, including the identification and classification of dangerous substances, the evolving nature of hazardous materials, and jurisdictional issues. Moreover, the study critically analyzes the impact of international conventions and European Union standards on Serbian law, exploring how global trends influence domestic legal frameworks. The paper concludes by offering recommendations for enhancing the efficacy of Article 266, suggesting legislative reforms, raising public awareness, and improving inter-agency collaboration to effectively combat the illegal handling of hazardous materials in Serbia. U radu se analiziraju pravni i praktični aspekti člana 266.
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