The management of roads, as well as their maintenance, calls for an adequate assessment of the load-bearing capacity of the pavement structure. This serves as the basis on which future maintenance ...requirements are planned and plays a significant role in determining whether the rehabilitation or reconstruction of the pavement structure is required. The stability of the pavement structure depends on a large number of parameters, and it is not possible to fully assess all of them when making an estimation. One of the most significant parameters is the modulus of elasticity of asphalt layers (EAC). The goal of this study is to use models based on machine learning to perform a quick and efficient assessment of the modulus of elasticity of asphalt layers, as well as to compare the formed models. The paper defines models for EAC estimation using machine learning, in which the input data include the measured deflections and the temperature of the upper surface of the asphalt layer. Analyses of modeling using artificial neural networks (ANNs), support vector machines (SVMs) and boosted regression trees (BRT) were compared. The SVM method showed a higher accuracy in estimating the EAC modulus, with a mean absolute percentage error (MAPE) of 7.64%, while the ANN method and the BRT achieved accuracies of 9.13% and 8.84%, respectively. Models formed in this way can be practically implemented in the management and maintenance of roads. They enable an adequate assessment of the remaining load-bearing capacity and the level of reliability of the pavement structure using non-destructive methods, at the same time reducing the financial costs.
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.
In recent decades, sediment has been recognised as a problematic resource due to its potentially harmful effects and the large quantities present in water bodies. There is a need to properly manage ...large quantities of dredged sediments so that they can be used as a resource and not necessarily treated as a waste product. This research investigates the effects of ageing and maturation of solidified/stabilized mixtures of contaminated sediment with fly ash and lime. The effects of ageing on the microstructural properties and chemical integrity of mixtures were studied for 7 days, 28 days, and 7 years using scanning electron microscopy and energy dispersive spectroscopy (SEM/EDS), X-ray diffraction analysis (XRD), and DIN (German Standard Procedure for Water, Wastewater and Sediment Testing (Group S)) and TCLP (Toxicity Characteristic Leaching Procedure) leaching tests. The results of the microstructure and strength analysis showed that the use of fly ash and lime as binders promoted the permanent structural integrity of the sediment. The treated sediment with 20 wt% fly ash and 10 wt% lime (F20L10) achieved higher overall strength compared to the mixture containing only 30 wt% fly ash (F30). The speciation and redistribution of metals and As in the treated sediment mixtures during the long-term evaluation indicate a strong reduction in their mobility. This material can be considered environmentally friendly and can be used as a fill material in road construction. The investment and operating costs are justified in this solution for sediment management. However, it is important to monitor the produced material over time to ensure that it remains effective and sustainable in the long term.
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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 objective of this research was to determine the probability of road overtopping occurrence for a road culvert caused by surface runoff from the upstream catchment. A hydrological–hydraulic model ...was used for the development of an algorithm for road culvert maintenance based on the overtopping occurrence probability (CMOOP algorithm) for small mountain catchments. The hydrological model defines the regression dependence between the runoff hydrograph peak values and the probability of occurrences, whereas the hydraulic model calculates the culvert flow capacity by including in the calculation the level of sediment that culvert is filled with. The relationship between occurrences of overtopping and peak runoff value was defined using the runoff hydrograph transformation model in the accumulation on the upstream side of the road. In addition to the calculation of overtopping occurrence probability for the existing culvert condition, the CMOOP algorithm was used to analyze the impact of rehabilitation and reconstruction works from the perspective of legally based safety criterion for road overtopping occurrence probability (SCROOP). The CMOOP algorithm was appled to 67 concrete culverts located in a mountain road section in the Republic of Serbia. The results show that the application of rehabilitation works on selected culverts will increase the percentage of culverts that satisfy SCROOP from 49.25% to 89.55%, which confirms that the accumulated stone sediment is the main reason for the SCROOP unfulfillment.
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.
This article presents research on qualitative parameters conducted in order to develop a model for the improvement of occupational health and safety (OHS) in micro and small construction enterprises ...(MSEs). Identification of factors and defining their significance enables improvements of OHS in the observed enterprises. The aim of the model is to assist MSEs in evaluating their qualities, pinpointing their deficiencies and ways to maximize the improvement of OHS performances. A panel of 20 experts defined the factors through an iterative process using the Delphi method. The research resulted in a model consisting of 42 OHS factors grouped into 10 categories. Model validation was carried out in the Republic of Serbia. The validation confirmed the applicability of the model as well as the relevance of factors that were determined by the panel of experts.
The aim of the research presented in this paper is the experimental confirmation of the numerically defined shapes of the Strut-and-Tie models, designed according to the EN 1992-1-1 recommendations, ...and obtained from the software “ST method”. Three reinforced concrete deep beams with openings were tested. Each of them had the same dimensions and quality of the material characteristics. The specimens, constructed as simply supported beams, were loaded with two concentrated forces and were tested for bending until failure. Each specimen was reinforced with different reinforcement layout determined by variation parameter β, incorporated in the software “ST method”. For the determination of the Strut-and-Tie models, all of the reinforcement layouts were equally favored in the first specimen (β = 1.0 for 0°, 45°, and 90°), only the horizontal direction was favored in the second (β = 1.0 for 0°), while in the third specimen the one at the angle of 45° (β = 1.0 for 45°). Based on the results of experimental research, it was concluded that the behavior of loaded members was in agreement with the proposed shapes of the Strut-and-Tie models that were used for their design, and it was confirmed that the program “ST method” can be used for obtaining Strut–and-Tie models.
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.
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