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Volume 16 (2021): Issue 2 (December 2021)

Volume 16 (2021): Issue 1 (June 2021)

Volume 15 (2020): Issue 2 (December 2020)

Volume 15 (2020): Issue 1 (September 2020)

Volume 14 (2019): Issue 2 (December 2019)

Volume 14 (2019): Issue 1 (December 2019)

Volume 13 (2018): Issue s1 (March 2018)
Special Issue

Volume 13 (2018): Issue 1 (December 2018)

Volume 12 (2017): Issue 2 (December 2017)

Volume 12 (2017): Issue 1 (June 2017)

Volume 11 (2016): Issue 2 (December 2016)

Volume 11 (2016): Issue 1 (June 2016)

Volume 10 (2015): Issue 2 (November 2015)

Volume 10 (2015): Issue 1 (June 2015)

Volume 9 (2014): Issue 2 (November 2014)

Volume 9 (2014): Issue 1 (June 2014)

Volume 8 (2013): Issue 2 (November 2013)

Volume 8 (2013): Issue 1 (June 2013)

Volume 7 (2012): Issue 2 (November 2012)

Volume 7 (2012): Issue 1 (June 2012)

Journal Details
Format
Journal
eISSN
1338-7278
First Published
29 Mar 2013
Publication timeframe
2 times per year
Languages
English

Search

Volume 12 (2017): Issue 2 (December 2017)

Journal Details
Format
Journal
eISSN
1338-7278
First Published
29 Mar 2013
Publication timeframe
2 times per year
Languages
English

Search

20 Articles
Open Access

Factors blocking the development of north – central Rzeszów

Published Online: 29 Dec 2017
Page range: 7 - 13

Abstract

Abstract

Rzeszów is one of the best developing cities in Poland. Once the small HQ of a principality - due to complicated historical conditioning - it has now become a place where an increasing number of people choose to live. The city with its bursting life, streets and squares starts and ends, however, in an area which only a few dozen years ago still catered for one fifth of the current population. The main reason for this phenomenon is the presence of spatial barriers, which significantly limit the development of the central urban area. This article analyzes the elements, which block the development of the north-central part of Rzeszów. An appropriate diagnosis of the problem may in the future allow the right actions in urban planning to be taken in order to cross these barriers. This may lead to the future development of areas with huge urbanization potential. Investments undertaken by city authorities to develop the northern peripheries of Rzeszów may trigger the development of the central district in this direction. This may occur as a result of concrete design interventions. The new part of the central district should have the scale and proportions of urban space that answer to the needs of a dynamically developing capital of the Podkarpacie region.

Keywords

  • urban reshaping
  • central Rzeszów
  • scale and proportions of urban space
  • revitalization of degraded areas
Open Access

Modelling of air flow supply in a room at variable regime by using both K - E and spalart – allmaras turbulent model

Published Online: 29 Dec 2017
Page range: 15 - 22

Abstract

Abstract

The abstract is to The article is devoted to the decision of actual task of air distribution efficiency increasing with the help of swirl and spread air jets to provide normative parameters of air in the production apartments. The mathematical model of air supply with swirl and spread air jets in that type of apartments is improved. It is shown that for reachin of air distribution maximal efficiency it is necessary to supply air by air jets, that intensively extinct before entering into a working area. Simulation of air flow performed with the help of CFD FLUENT (Ansys FLUENT). Сalculations of the equation by using one-parameter model of turbulence Spalart-Allmaras are presented. The graphical and the analytical dependences on the basis of the conducted experimental researches, which can be used in subsequent engineering calculations, are shown out. Dynamic parameters of air flow that is created due to swirl and spread air jets at their leakage at variable regime and creation of dynamic microclimate in a room has been determined. Results of experimental investigations of air supply into the room by air distribution device which creates swirl air jets for creation more intensive turbulization air flow in the room are presented. Obtained results of these investigations give possibility to realize engineer calculations of air distribution with swirl air jets. The results of theoretical researches of favourable influence of dynamic microclimate to the man are presented. When using dynamic microclimate, it’s possible to decrease conditioning and ventilation system expenses. Human organism reacts favourably on short lasting deviations from the rationed parameters of air environment.

Keywords

  • air distribution
  • swirl jet
  • spread jet
  • variable regime
  • air velocity
Open Access

Analysis of the systems of ventilation of residential houses of Ukraine and Estonia

Published Online: 29 Dec 2017
Page range: 23 - 30

Abstract

Abstract

The most common ventilation system in residential buildings in Ukraine is natural ventilation. In recent years, due to increased tightness of structures, an increase in the content of synthetic finishing materials in them, the quality of microclimate parameters deteriorated. One of the measures to improve the parameters of indoor air in residential buildings is the use of mechanical inflow and exhaust ventilation system. In this article the regulatory documents concerning the design of ventilation systems in Ukraine and Estonia and the requirements for air exchange in residential buildings are considered. It is established that the existing normative documents in Ukraine are analogous to European norms, which allow design the system of ventilation of residential buildings according to European standards. However, the basis for the design of ventilation systems in Ukraine is the national standards, in which mechanical ventilation, unfortunately, is provided only for the design of high-rise buildings. To maintain acceptable microclimate parameters in residential buildings, it is advisable for designers to apply the requirements for designing ventilation systems in accordance with European standards.

Keywords

  • microclimate parameters
  • natural ventilation system
  • mechanical ventilation system
  • air exchange
Open Access

Economic efficiency of application of solar window

Published Online: 29 Dec 2017
Page range: 31 - 38

Abstract

Abstract

Priority and qualitatively new direction in the fuel and energy sector is renewable energy. This paper describes a feasibility study of using solar window in the system of solar heat supply. The article presents literature data about the effectiveness of the use of solar systems in other countries. The results confirm a sufficient efficiency of solar heat supply with using solar Windows. Insights based on practical experience and mathematical calculations, which are aimed at a detailed explanation of economic efficiency of the proposed construction.

Keywords

  • a solar window
  • economic efficiency
  • net present value
  • cost
Open Access

The improved design method of shear strength of reinforced concrete beams without transverse reinforcement

Published Online: 29 Dec 2017
Page range: 39 - 45

Abstract

Abstract

In this article, results of experimental testing of reinforced concrete beams without transverse shear reinforcement are given. Three prototypes for improved testing methods were tested. The testing variable parameter was the shear span to the effective depth ratio. In the result of the tests we noticed that bearing capacity of RC beams is increased with the decreasing shear span to the effective depth ratio. The design method according to current codes was applied to test samples and it showed a significant discrepancy results. Than we proposed the improved design method using the adjusted value of shear strength of concrete CRd,c. The results obtained by the improved design method showed satisfactory reproducibility.

Keywords

  • design
  • shear strength
  • RC beam
Open Access

A Polish approach to FRP bridges

Published Online: 29 Dec 2017
Page range: 47 - 54

Abstract

Abstract

The paper presents initial results of a new approach to FRP composite bridge construction that is presently being developed and tested in Poland. The concept combines lightweight concrete with FRP composites to create a durable highly optimised structure. The paper describes the bridge system itself and presents the research results on its development. The basic design is presented together with research results on its development: FEM analysis and a range of static test results of full-scale bridge beam experiments. The paper finishes with some test results of a full scale bridge that was constructed near Rzeszow in December 2015.

Keywords

  • FRP composites
  • bridge
  • hybrid structure
  • FEM analysis
  • testing
  • construction
Open Access

Initial research on recycled tyre bales for road infrastructure applications

Published Online: 29 Dec 2017
Page range: 55 - 62

Abstract

Abstract

The paper reviews selected surveys carried out within the R&D project, co-financed with the European Regional Development Fund, called “ReUse - Innovative Recycling Materials, Enhancing the Sustainability of Bridge Facilities” (Innotech No. K3 / IN3 / 38/228116 / NCBiR / 15). The aim of the project and conducted research is to develop and implement innovative, cheap and environmentally-friendly recycled construction material in the form of tyre bales made from compressed used car tyres. This material is likely to be applied in civil engineering, especially in transport infrastructure, geotechnical and hydraulic engineering. New material is cheap and has unique properties such as low weight, high water permeability, high vibration and noise-damping capacity, low pressure coefficient values and other parameters that technically and economically allow it to replace natural aggregates. The extensive practical application of new material will facilitate the replacement of waste management methods with the environmentally friendly ones.

Keywords

  • aggregate
  • earth structures
  • tyre recycling
  • tyre bales
  • R&D project
Open Access

Numerical modelling of the reinforced concrete influence on a combined system of tunnel support

Published Online: 29 Dec 2017
Page range: 63 - 70

Abstract

Abstract

The paper presents the experimental, laboratory determined rheological-dynamic analysis of the properties of fiber reinforced concrete, which was then utilized to show nonlinear analysis of combined system of tunnel support structure. According to the performed experiments and calculations, different processes of destructive behavior of tunnel lining were simulated in combination with elastic and elastic-plastic behavior of materials taking into account the tunnel loading, the interaction between the fiber reinforced concrete and soil, as well as the interaction between the fiber reinforced concrete and the inner lining of the tunnel.

Keywords

  • reinforced concrete
  • nonlinear analysis
  • combined system of the tunnel
Open Access

Costs of performance based maintenance for local roads: Case study Albania

Published Online: 29 Dec 2017
Page range: 71 - 78

Abstract

Abstract

The provision and maintenance of road infrastructure is a major global business, consequently it is essential that road maintenance services are provided in the most cost effective manner. Without regular maintenance, roads can rapidly fall into disrepair, preventing realization of the longer term impacts of road improvements on development, such as increased agricultural production and growth in school enrollment, which is of particular importance for a network of local (access) roads. Inadequate local roads maintenance in Albania is proposed to be solved by implementing performance based maintenance approach for which the costing exercise is presented within the paper.

Keywords

  • local roads
  • performance based maintenance
  • maintenance costs
  • road user costs
Open Access

Modeling of porous concrete elements under load

Published Online: 29 Dec 2017
Page range: 79 - 86

Abstract

Abstract

It is known that cell concretes are almost immediately destroyed under load, having reached certain critical stresses. Such kind of destruction is called a “catastrophic failure”. Process of crack formation is one of the main factors, influencing process of concrete destruction. Modern theory of crack formation is mainly based on the Griffith theory of destruction. However, the mentioned theory does not completely correspond to the structure of cell concrete with its cell structure, because the theory is intended for a solid body. The article presents one of the possible variants of modelling of the structure of cell concrete and gives some assumptions concerning the process of crack formation in such hollow, not solid environment.

Keywords

  • cell concrete
  • catastrophic failure
  • crack formation
  • bubble cell
  • ball
  • space model
Open Access

Facade renovation – replacement and restoration of the panels in a monument protected object

Published Online: 29 Dec 2017
Page range: 87 - 94

Abstract

Abstract

The article deals with problems of reconstruction of the facade and the associated problem of replacement or repair of the panels. In conventional buildings it is a smooth operation, but it is problematic in monument-protected objects. In the case of a common building, it is possible to choose any modern panels and simply replace them, but for historical objects we have to follow the claims and the rules of monument protection. In practice, it usually means the impossibility of use of modern panels, but at least a combination of old and modern technologies. Another possible solution to the problem is renovation, or repairs to the original state of the existing panels, of course with respect to the functionality of such panels. The implementation of such repairs must always be based on the technical and historical survey of the condition of the object and the repairs must be professionally designed. Subsequently, corrections are made, during which it is necessary to pay particular attention to observance of the technological procedures, rules and instructions particularly in terms of monument protection. However, the functionality of the works or elements made with regard to the quality of the environment within the building is not negligible. A common problem is the lack of control of technical requirements and functional requirements. Underestimation of the problems then leads to difficult repairs. The article points to the mistakes and problems of one such construction project on a historically protected chateau building.

Keywords

  • Restoration
  • renovation
  • monument protected object
  • windows and doors
  • refurbishment
  • exploration
  • repair
  • functional defect
  • implementation defect
Open Access

Effect of mineral additives on structure and properties of concrete for pavements

Published Online: 29 Dec 2017
Page range: 95 - 100

Abstract

Abstract

Concrete pavements is an attractive alternative to asphalt pavements because of its lower cost and higher durability. Major contribution to sustainable development can be made by partial replacement of cement in concrete pavement with supplementary cementitious materials of different nature and origin. In this paper, the effect of natural zeolite and perlite additives in complex with chemical admixtures on the structure and properties of concrete for pavement was studied. Compressive and flexural strength test was used to study the mechanical behavior of designed concrete under load. Generally, the compressive strength of both control concrete and concrete containing mineral additives levels at the later ages of hardening. The microstructure analysis of concrete with mineral additives of different nature activity showed the formation of additional amount of hydration products such as tobermorite type calcium hydrosilicate which provide self-reinforcement of hardening concrete system.

Keywords

  • pavement concrete
  • slag
  • zeolite
  • perlite
  • compressive strength
  • structure
Open Access

Peculiarities of hydration of Portland cement with synthetic nano-silica

Published Online: 29 Dec 2017
Page range: 101 - 106

Abstract

Abstract

Application of nano-materials in cement products significantly, improves their properties. Of course, the effectiveness of the materials depends on their quantity and the way they are introduced into the system. So far, amongst nano-materials used in construction, the most preferred was nano-silica. This research investigated the effect of synthetic precipitated nano-silica on the cement hydration as well as, on the physical and mechanical properties of pastes and mortars. Obtained results showed that admixture of nano-silica enhanced flexural and compressive strength of cement after 2 and 28 days, however, only when admixture made up 0.5% and 1.0%. On the other hand, the use of nano-silica in the amount 2% had some limitations, due to its ability to agglomerate, which resulted in deterioration of the rheological and mechanical properties.

Keywords

  • nano-silica
  • Portland cement
  • hydration
  • calorimetric
  • paste
  • mortar
  • setting time
  • rate evolution of heat
  • flexural and compressive strength
Open Access

Design of rapid hardening engineered cementitious composites for sustainable construction

Published Online: 29 Dec 2017
Page range: 107 - 112

Abstract

Abstract

This paper deals with design of environmentally friendly Rapid Hardening Engineered Cementitious Composite (RHECC) nanomodified with ultrafine mineral additives, polycarboxylate ether based superplasticizer, calcium hydrosilicate nanoparticles and dispersal reinforced by fibers. The incremental coefficient of surface activity was proposed in order to estimation of ultrafine supplementary materials (fly ash, methakaolin, microsilica) efficiency. A characterization of RHECC’s compressive and flexural properties at different ages is reported in this paper. Early compressive strength of ECC is 45-50 MPa, standard strength – 84-95 MPa and parameter Rc2/Rc28 – 65–70%. The microstructure of the cement matrix and RHECC was investigated. The use of ultrafine mineral supplementary materials provides reinforcement of structure on micro- and nanoscale level (cementing matrix) due to formation of sub-microreinforcing hydrate phase as AFt- and C-S-H phases in unclinker part of cement matrix, resulting in the phenomena of “self-reinforcement” on the microstructure level. Designed RHECC may be regarded as lower brittle since the crack resistance coefficient is higher comparison to conventional fine grain concrete.

Keywords

  • Rapid Hardening Engineered Cementitious Composite
  • nanomodification
  • ultrafine additives
  • polycarboxylate ether based superplasticizer
  • sustainable development
Open Access

BIM integration in education: A case study of the construction technology project Bolt Tower Dolni Vitkovice

Published Online: 29 Dec 2017
Page range: 113 - 120

Abstract

Abstract

Building information modeling (BIM) can support effectiveness during many activities in the AEC industry. even when processing a construction-technological project. This paper presents an approach how to use building information model in higher education, especially during the work on diploma thesis and it supervision. Diploma thesis is project based work, which aims to compile a construction-technological project for a selected construction. The paper describes the use of input data, working with them and compares this process with standard input data such as printed design documentation. The effectiveness of using the building information model as a input data for construction-technological project is described in the conclusion.

Keywords

  • building information model
  • BIM
  • teaching
  • construction management
  • steel structure
Open Access

The potential of bioash for utilization in road construction in eastern Croatia

Published Online: 29 Dec 2017
Page range: 121 - 127

Abstract

Abstract

In recent years usage of biomass as energy source has intensified in eastern Croatia. Newly built biomass power plants generate great amounts of bioash that is being disposed at landfills. Due to its favorable properties bioashes could be reused as alternative materials in road construction or road fundation. Therefore, research on application of bioashes in construction industry is being conducted at Faculty of Civil Engineering in Osijek. The main motivation behind this research, in a form of biomass and bioash production in eastern Croatia as well as international research on potential application of this types of bioashes, is show in this paper.

Keywords

  • biomass
  • bioash
  • road construction
  • eastern Croatia
  • waste recycling
Open Access

The use of modern technologies in carbon dioxide monitoring

Published Online: 29 Dec 2017
Page range: 129 - 137

Abstract

Abstract

Indoor environment has huge influence on person’s health and overall comfort. It is of great importance that we realize how essential indoor air quality is, considering we spend on average as much as 90% of our time indoors. There are many factors that affect indoor air quality: specifically, inside air temperature, relative humidity, and odors to name the most important factors. One of the key factors indicating indoor air quality is carbon dioxide (CO2) level.

The CO2 levels, measured in prefab apartment buildings, indicates substantial indoor air quality issues. Therefore, a proper education of the occupants is of utmost importance. Also, great care should be directed towards technical and technological solutions that would ensure meeting the normative indoor environment criteria, especially indoor air CO2 levels. Thanks to the implementation of new emerging autonomous technologies, such as Internet of Things (IoT), monitoring in real-time is enhanced. An area where IoT plays a major role is in the monitoring of indoor environment. IoT technology (e.g. smart meters and sensors) provide awareness of information about the quality of indoor environment. There is a huge potential for influencing behaviour of the users. Through the web application, it is possible to educate people and ensure fresh air supply.

Keywords

  • carbon dioxide
  • indoor air environment
  • monitoring
  • internet of things
  • smart sensors
  • people behaviour
Open Access

Influence of transit water flow rate on its dispensation and on inflow through nozzles in pressure pipeline under action of external pressure

Published Online: 29 Dec 2017
Page range: 139 - 146

Abstract

Abstract

The influence of transit flow rate of water upon operative of the equipped with nozzles pressure pipeline is experimentally investigated. External pressure, which varies in the range of 1465-2295 mm, acted upon the pipeline. The angle β between vectors of velocities of the stream in the pipeline and jets which branch off through nozzles were given the value: ; 45° ; 90° ; 135° ; 180°. The diameter of the pipeline was of D=20.18 mm, the diameter of nozzles d=6.01 mm. The distances between the nozzles were 180 mm, and the number of them 11. The value of the transit flow rate at input into the pipeline varied from 4.05 to 130.20 cm3 / s. The increase in flow rate of the transit flux Qtr caused increase in non-uniformity of distribution of operating heads and increase in flow rate of water along the pipeline over the segment of its dispensation. On the segment of collecting of water, inverse tendency was observed. The number of nozzles through which water became to be dispensed increased with the increase in Qtr.

Keywords

  • dispensation pipeline
  • pipeline-collector
  • variable mass fluid flow
Open Access

Expansive cements for the manufacture of the concrete protective bandages

Published Online: 29 Dec 2017
Page range: 147 - 154

Abstract

Abstract

One of the promising directions of the use of expansive cements is making the protective bandages for the maintenance of pipelines. Bandages expansive application of the compositions of the pipeline reinforce the damaged area and reduce stress due to compressive stress in the cylindrical area. Such requirements are best suited for expansive compositions obtained from portland cement and modified quicklime. The article presents the results of expansive cements based on quick lime in order to implement protective bandages pipelines.

Keywords

  • expanding cement
  • quicklime
  • expansion effort
  • strength of bending and compressive
Open Access

Possibility of heat recovery from gray water in residential building

Published Online: 29 Dec 2017
Page range: 155 - 162

Abstract

Abstract

Recovery of waste heat from gray water can be an interesting alternative to other energy saving systems in a building, including alternative energy sources. Mainly, due to a number of advantages including independence from weather conditions, small investment outlay, lack of user support, or a slight interference with the installation system. The purpose of this article is to present the financial effectiveness of installations which provide hot, usable water to a detached house, using a Drain Water Heat Recovery (DWHR) system depending on the number of system users and the various combinations of bathing time in the shower, which has an influence on the daily warm water demand in each of the considered options. The economic analysis of the adopted installation variants is based on the Life Cycle Cost (LCC) method, which is characterized by the fact that it also includes the operating costs in addition to the capital expenditure during the entire analysis period. For each case, the necessary devices were selected and the cost of their installation was estimated.

Keywords

  • heat recovery
  • heat exchanger
  • hot water
  • DWHR
  • Life Cycle Cost
  • LCC
20 Articles
Open Access

Factors blocking the development of north – central Rzeszów

Published Online: 29 Dec 2017
Page range: 7 - 13

Abstract

Abstract

Rzeszów is one of the best developing cities in Poland. Once the small HQ of a principality - due to complicated historical conditioning - it has now become a place where an increasing number of people choose to live. The city with its bursting life, streets and squares starts and ends, however, in an area which only a few dozen years ago still catered for one fifth of the current population. The main reason for this phenomenon is the presence of spatial barriers, which significantly limit the development of the central urban area. This article analyzes the elements, which block the development of the north-central part of Rzeszów. An appropriate diagnosis of the problem may in the future allow the right actions in urban planning to be taken in order to cross these barriers. This may lead to the future development of areas with huge urbanization potential. Investments undertaken by city authorities to develop the northern peripheries of Rzeszów may trigger the development of the central district in this direction. This may occur as a result of concrete design interventions. The new part of the central district should have the scale and proportions of urban space that answer to the needs of a dynamically developing capital of the Podkarpacie region.

Keywords

  • urban reshaping
  • central Rzeszów
  • scale and proportions of urban space
  • revitalization of degraded areas
Open Access

Modelling of air flow supply in a room at variable regime by using both K - E and spalart – allmaras turbulent model

Published Online: 29 Dec 2017
Page range: 15 - 22

Abstract

Abstract

The abstract is to The article is devoted to the decision of actual task of air distribution efficiency increasing with the help of swirl and spread air jets to provide normative parameters of air in the production apartments. The mathematical model of air supply with swirl and spread air jets in that type of apartments is improved. It is shown that for reachin of air distribution maximal efficiency it is necessary to supply air by air jets, that intensively extinct before entering into a working area. Simulation of air flow performed with the help of CFD FLUENT (Ansys FLUENT). Сalculations of the equation by using one-parameter model of turbulence Spalart-Allmaras are presented. The graphical and the analytical dependences on the basis of the conducted experimental researches, which can be used in subsequent engineering calculations, are shown out. Dynamic parameters of air flow that is created due to swirl and spread air jets at their leakage at variable regime and creation of dynamic microclimate in a room has been determined. Results of experimental investigations of air supply into the room by air distribution device which creates swirl air jets for creation more intensive turbulization air flow in the room are presented. Obtained results of these investigations give possibility to realize engineer calculations of air distribution with swirl air jets. The results of theoretical researches of favourable influence of dynamic microclimate to the man are presented. When using dynamic microclimate, it’s possible to decrease conditioning and ventilation system expenses. Human organism reacts favourably on short lasting deviations from the rationed parameters of air environment.

Keywords

  • air distribution
  • swirl jet
  • spread jet
  • variable regime
  • air velocity
Open Access

Analysis of the systems of ventilation of residential houses of Ukraine and Estonia

Published Online: 29 Dec 2017
Page range: 23 - 30

Abstract

Abstract

The most common ventilation system in residential buildings in Ukraine is natural ventilation. In recent years, due to increased tightness of structures, an increase in the content of synthetic finishing materials in them, the quality of microclimate parameters deteriorated. One of the measures to improve the parameters of indoor air in residential buildings is the use of mechanical inflow and exhaust ventilation system. In this article the regulatory documents concerning the design of ventilation systems in Ukraine and Estonia and the requirements for air exchange in residential buildings are considered. It is established that the existing normative documents in Ukraine are analogous to European norms, which allow design the system of ventilation of residential buildings according to European standards. However, the basis for the design of ventilation systems in Ukraine is the national standards, in which mechanical ventilation, unfortunately, is provided only for the design of high-rise buildings. To maintain acceptable microclimate parameters in residential buildings, it is advisable for designers to apply the requirements for designing ventilation systems in accordance with European standards.

Keywords

  • microclimate parameters
  • natural ventilation system
  • mechanical ventilation system
  • air exchange
Open Access

Economic efficiency of application of solar window

Published Online: 29 Dec 2017
Page range: 31 - 38

Abstract

Abstract

Priority and qualitatively new direction in the fuel and energy sector is renewable energy. This paper describes a feasibility study of using solar window in the system of solar heat supply. The article presents literature data about the effectiveness of the use of solar systems in other countries. The results confirm a sufficient efficiency of solar heat supply with using solar Windows. Insights based on practical experience and mathematical calculations, which are aimed at a detailed explanation of economic efficiency of the proposed construction.

Keywords

  • a solar window
  • economic efficiency
  • net present value
  • cost
Open Access

The improved design method of shear strength of reinforced concrete beams without transverse reinforcement

Published Online: 29 Dec 2017
Page range: 39 - 45

Abstract

Abstract

In this article, results of experimental testing of reinforced concrete beams without transverse shear reinforcement are given. Three prototypes for improved testing methods were tested. The testing variable parameter was the shear span to the effective depth ratio. In the result of the tests we noticed that bearing capacity of RC beams is increased with the decreasing shear span to the effective depth ratio. The design method according to current codes was applied to test samples and it showed a significant discrepancy results. Than we proposed the improved design method using the adjusted value of shear strength of concrete CRd,c. The results obtained by the improved design method showed satisfactory reproducibility.

Keywords

  • design
  • shear strength
  • RC beam
Open Access

A Polish approach to FRP bridges

Published Online: 29 Dec 2017
Page range: 47 - 54

Abstract

Abstract

The paper presents initial results of a new approach to FRP composite bridge construction that is presently being developed and tested in Poland. The concept combines lightweight concrete with FRP composites to create a durable highly optimised structure. The paper describes the bridge system itself and presents the research results on its development. The basic design is presented together with research results on its development: FEM analysis and a range of static test results of full-scale bridge beam experiments. The paper finishes with some test results of a full scale bridge that was constructed near Rzeszow in December 2015.

Keywords

  • FRP composites
  • bridge
  • hybrid structure
  • FEM analysis
  • testing
  • construction
Open Access

Initial research on recycled tyre bales for road infrastructure applications

Published Online: 29 Dec 2017
Page range: 55 - 62

Abstract

Abstract

The paper reviews selected surveys carried out within the R&D project, co-financed with the European Regional Development Fund, called “ReUse - Innovative Recycling Materials, Enhancing the Sustainability of Bridge Facilities” (Innotech No. K3 / IN3 / 38/228116 / NCBiR / 15). The aim of the project and conducted research is to develop and implement innovative, cheap and environmentally-friendly recycled construction material in the form of tyre bales made from compressed used car tyres. This material is likely to be applied in civil engineering, especially in transport infrastructure, geotechnical and hydraulic engineering. New material is cheap and has unique properties such as low weight, high water permeability, high vibration and noise-damping capacity, low pressure coefficient values and other parameters that technically and economically allow it to replace natural aggregates. The extensive practical application of new material will facilitate the replacement of waste management methods with the environmentally friendly ones.

Keywords

  • aggregate
  • earth structures
  • tyre recycling
  • tyre bales
  • R&D project
Open Access

Numerical modelling of the reinforced concrete influence on a combined system of tunnel support

Published Online: 29 Dec 2017
Page range: 63 - 70

Abstract

Abstract

The paper presents the experimental, laboratory determined rheological-dynamic analysis of the properties of fiber reinforced concrete, which was then utilized to show nonlinear analysis of combined system of tunnel support structure. According to the performed experiments and calculations, different processes of destructive behavior of tunnel lining were simulated in combination with elastic and elastic-plastic behavior of materials taking into account the tunnel loading, the interaction between the fiber reinforced concrete and soil, as well as the interaction between the fiber reinforced concrete and the inner lining of the tunnel.

Keywords

  • reinforced concrete
  • nonlinear analysis
  • combined system of the tunnel
Open Access

Costs of performance based maintenance for local roads: Case study Albania

Published Online: 29 Dec 2017
Page range: 71 - 78

Abstract

Abstract

The provision and maintenance of road infrastructure is a major global business, consequently it is essential that road maintenance services are provided in the most cost effective manner. Without regular maintenance, roads can rapidly fall into disrepair, preventing realization of the longer term impacts of road improvements on development, such as increased agricultural production and growth in school enrollment, which is of particular importance for a network of local (access) roads. Inadequate local roads maintenance in Albania is proposed to be solved by implementing performance based maintenance approach for which the costing exercise is presented within the paper.

Keywords

  • local roads
  • performance based maintenance
  • maintenance costs
  • road user costs
Open Access

Modeling of porous concrete elements under load

Published Online: 29 Dec 2017
Page range: 79 - 86

Abstract

Abstract

It is known that cell concretes are almost immediately destroyed under load, having reached certain critical stresses. Such kind of destruction is called a “catastrophic failure”. Process of crack formation is one of the main factors, influencing process of concrete destruction. Modern theory of crack formation is mainly based on the Griffith theory of destruction. However, the mentioned theory does not completely correspond to the structure of cell concrete with its cell structure, because the theory is intended for a solid body. The article presents one of the possible variants of modelling of the structure of cell concrete and gives some assumptions concerning the process of crack formation in such hollow, not solid environment.

Keywords

  • cell concrete
  • catastrophic failure
  • crack formation
  • bubble cell
  • ball
  • space model
Open Access

Facade renovation – replacement and restoration of the panels in a monument protected object

Published Online: 29 Dec 2017
Page range: 87 - 94

Abstract

Abstract

The article deals with problems of reconstruction of the facade and the associated problem of replacement or repair of the panels. In conventional buildings it is a smooth operation, but it is problematic in monument-protected objects. In the case of a common building, it is possible to choose any modern panels and simply replace them, but for historical objects we have to follow the claims and the rules of monument protection. In practice, it usually means the impossibility of use of modern panels, but at least a combination of old and modern technologies. Another possible solution to the problem is renovation, or repairs to the original state of the existing panels, of course with respect to the functionality of such panels. The implementation of such repairs must always be based on the technical and historical survey of the condition of the object and the repairs must be professionally designed. Subsequently, corrections are made, during which it is necessary to pay particular attention to observance of the technological procedures, rules and instructions particularly in terms of monument protection. However, the functionality of the works or elements made with regard to the quality of the environment within the building is not negligible. A common problem is the lack of control of technical requirements and functional requirements. Underestimation of the problems then leads to difficult repairs. The article points to the mistakes and problems of one such construction project on a historically protected chateau building.

Keywords

  • Restoration
  • renovation
  • monument protected object
  • windows and doors
  • refurbishment
  • exploration
  • repair
  • functional defect
  • implementation defect
Open Access

Effect of mineral additives on structure and properties of concrete for pavements

Published Online: 29 Dec 2017
Page range: 95 - 100

Abstract

Abstract

Concrete pavements is an attractive alternative to asphalt pavements because of its lower cost and higher durability. Major contribution to sustainable development can be made by partial replacement of cement in concrete pavement with supplementary cementitious materials of different nature and origin. In this paper, the effect of natural zeolite and perlite additives in complex with chemical admixtures on the structure and properties of concrete for pavement was studied. Compressive and flexural strength test was used to study the mechanical behavior of designed concrete under load. Generally, the compressive strength of both control concrete and concrete containing mineral additives levels at the later ages of hardening. The microstructure analysis of concrete with mineral additives of different nature activity showed the formation of additional amount of hydration products such as tobermorite type calcium hydrosilicate which provide self-reinforcement of hardening concrete system.

Keywords

  • pavement concrete
  • slag
  • zeolite
  • perlite
  • compressive strength
  • structure
Open Access

Peculiarities of hydration of Portland cement with synthetic nano-silica

Published Online: 29 Dec 2017
Page range: 101 - 106

Abstract

Abstract

Application of nano-materials in cement products significantly, improves their properties. Of course, the effectiveness of the materials depends on their quantity and the way they are introduced into the system. So far, amongst nano-materials used in construction, the most preferred was nano-silica. This research investigated the effect of synthetic precipitated nano-silica on the cement hydration as well as, on the physical and mechanical properties of pastes and mortars. Obtained results showed that admixture of nano-silica enhanced flexural and compressive strength of cement after 2 and 28 days, however, only when admixture made up 0.5% and 1.0%. On the other hand, the use of nano-silica in the amount 2% had some limitations, due to its ability to agglomerate, which resulted in deterioration of the rheological and mechanical properties.

Keywords

  • nano-silica
  • Portland cement
  • hydration
  • calorimetric
  • paste
  • mortar
  • setting time
  • rate evolution of heat
  • flexural and compressive strength
Open Access

Design of rapid hardening engineered cementitious composites for sustainable construction

Published Online: 29 Dec 2017
Page range: 107 - 112

Abstract

Abstract

This paper deals with design of environmentally friendly Rapid Hardening Engineered Cementitious Composite (RHECC) nanomodified with ultrafine mineral additives, polycarboxylate ether based superplasticizer, calcium hydrosilicate nanoparticles and dispersal reinforced by fibers. The incremental coefficient of surface activity was proposed in order to estimation of ultrafine supplementary materials (fly ash, methakaolin, microsilica) efficiency. A characterization of RHECC’s compressive and flexural properties at different ages is reported in this paper. Early compressive strength of ECC is 45-50 MPa, standard strength – 84-95 MPa and parameter Rc2/Rc28 – 65–70%. The microstructure of the cement matrix and RHECC was investigated. The use of ultrafine mineral supplementary materials provides reinforcement of structure on micro- and nanoscale level (cementing matrix) due to formation of sub-microreinforcing hydrate phase as AFt- and C-S-H phases in unclinker part of cement matrix, resulting in the phenomena of “self-reinforcement” on the microstructure level. Designed RHECC may be regarded as lower brittle since the crack resistance coefficient is higher comparison to conventional fine grain concrete.

Keywords

  • Rapid Hardening Engineered Cementitious Composite
  • nanomodification
  • ultrafine additives
  • polycarboxylate ether based superplasticizer
  • sustainable development
Open Access

BIM integration in education: A case study of the construction technology project Bolt Tower Dolni Vitkovice

Published Online: 29 Dec 2017
Page range: 113 - 120

Abstract

Abstract

Building information modeling (BIM) can support effectiveness during many activities in the AEC industry. even when processing a construction-technological project. This paper presents an approach how to use building information model in higher education, especially during the work on diploma thesis and it supervision. Diploma thesis is project based work, which aims to compile a construction-technological project for a selected construction. The paper describes the use of input data, working with them and compares this process with standard input data such as printed design documentation. The effectiveness of using the building information model as a input data for construction-technological project is described in the conclusion.

Keywords

  • building information model
  • BIM
  • teaching
  • construction management
  • steel structure
Open Access

The potential of bioash for utilization in road construction in eastern Croatia

Published Online: 29 Dec 2017
Page range: 121 - 127

Abstract

Abstract

In recent years usage of biomass as energy source has intensified in eastern Croatia. Newly built biomass power plants generate great amounts of bioash that is being disposed at landfills. Due to its favorable properties bioashes could be reused as alternative materials in road construction or road fundation. Therefore, research on application of bioashes in construction industry is being conducted at Faculty of Civil Engineering in Osijek. The main motivation behind this research, in a form of biomass and bioash production in eastern Croatia as well as international research on potential application of this types of bioashes, is show in this paper.

Keywords

  • biomass
  • bioash
  • road construction
  • eastern Croatia
  • waste recycling
Open Access

The use of modern technologies in carbon dioxide monitoring

Published Online: 29 Dec 2017
Page range: 129 - 137

Abstract

Abstract

Indoor environment has huge influence on person’s health and overall comfort. It is of great importance that we realize how essential indoor air quality is, considering we spend on average as much as 90% of our time indoors. There are many factors that affect indoor air quality: specifically, inside air temperature, relative humidity, and odors to name the most important factors. One of the key factors indicating indoor air quality is carbon dioxide (CO2) level.

The CO2 levels, measured in prefab apartment buildings, indicates substantial indoor air quality issues. Therefore, a proper education of the occupants is of utmost importance. Also, great care should be directed towards technical and technological solutions that would ensure meeting the normative indoor environment criteria, especially indoor air CO2 levels. Thanks to the implementation of new emerging autonomous technologies, such as Internet of Things (IoT), monitoring in real-time is enhanced. An area where IoT plays a major role is in the monitoring of indoor environment. IoT technology (e.g. smart meters and sensors) provide awareness of information about the quality of indoor environment. There is a huge potential for influencing behaviour of the users. Through the web application, it is possible to educate people and ensure fresh air supply.

Keywords

  • carbon dioxide
  • indoor air environment
  • monitoring
  • internet of things
  • smart sensors
  • people behaviour
Open Access

Influence of transit water flow rate on its dispensation and on inflow through nozzles in pressure pipeline under action of external pressure

Published Online: 29 Dec 2017
Page range: 139 - 146

Abstract

Abstract

The influence of transit flow rate of water upon operative of the equipped with nozzles pressure pipeline is experimentally investigated. External pressure, which varies in the range of 1465-2295 mm, acted upon the pipeline. The angle β between vectors of velocities of the stream in the pipeline and jets which branch off through nozzles were given the value: ; 45° ; 90° ; 135° ; 180°. The diameter of the pipeline was of D=20.18 mm, the diameter of nozzles d=6.01 mm. The distances between the nozzles were 180 mm, and the number of them 11. The value of the transit flow rate at input into the pipeline varied from 4.05 to 130.20 cm3 / s. The increase in flow rate of the transit flux Qtr caused increase in non-uniformity of distribution of operating heads and increase in flow rate of water along the pipeline over the segment of its dispensation. On the segment of collecting of water, inverse tendency was observed. The number of nozzles through which water became to be dispensed increased with the increase in Qtr.

Keywords

  • dispensation pipeline
  • pipeline-collector
  • variable mass fluid flow
Open Access

Expansive cements for the manufacture of the concrete protective bandages

Published Online: 29 Dec 2017
Page range: 147 - 154

Abstract

Abstract

One of the promising directions of the use of expansive cements is making the protective bandages for the maintenance of pipelines. Bandages expansive application of the compositions of the pipeline reinforce the damaged area and reduce stress due to compressive stress in the cylindrical area. Such requirements are best suited for expansive compositions obtained from portland cement and modified quicklime. The article presents the results of expansive cements based on quick lime in order to implement protective bandages pipelines.

Keywords

  • expanding cement
  • quicklime
  • expansion effort
  • strength of bending and compressive
Open Access

Possibility of heat recovery from gray water in residential building

Published Online: 29 Dec 2017
Page range: 155 - 162

Abstract

Abstract

Recovery of waste heat from gray water can be an interesting alternative to other energy saving systems in a building, including alternative energy sources. Mainly, due to a number of advantages including independence from weather conditions, small investment outlay, lack of user support, or a slight interference with the installation system. The purpose of this article is to present the financial effectiveness of installations which provide hot, usable water to a detached house, using a Drain Water Heat Recovery (DWHR) system depending on the number of system users and the various combinations of bathing time in the shower, which has an influence on the daily warm water demand in each of the considered options. The economic analysis of the adopted installation variants is based on the Life Cycle Cost (LCC) method, which is characterized by the fact that it also includes the operating costs in addition to the capital expenditure during the entire analysis period. For each case, the necessary devices were selected and the cost of their installation was estimated.

Keywords

  • heat recovery
  • heat exchanger
  • hot water
  • DWHR
  • Life Cycle Cost
  • LCC

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