bluuebunny/crossref_metadata_2025 huggingface dataset:
Fabrication of Polyethersulfone (PES) Membrane Incorporated with Graphitic Carbon Nitride (g-C3N4) Nanoparticles in Palm Oil Mill Effluent (POME) Wastewater Treatment
Authors: Wai Cheong Kin , Hon Leong Kah , Yong Ling Wong
Published: December 2021

Backed by the evolution in the nanotechnology field, membrane modified with nanoparticles as an additive has become increasingly prominent nowadays. The enormous potential of graphitic carbon nitride (g-C3N4) photocatalyst in wastewater treatment has been disclosed extensively. In this study, 4 Polyethersulfone (PES) membranes with different concentration of g-C3N4nanoparticles as additive were fabricated and their performances were investigated. Scanning Electron Microscopy (SEM) analysis showed that the membrane top surface layer was getting denser with the higher g-C3N4nanoparticles concentration which subsequently decreased the membrane mean pore size, porosity and flux. However the membrane with higher additive concentration was demonstrated a better improvement in anti-fouling properties where the flux recovery ratio (FRR) of the membranes showed an uptrend movement from 23.43% (membrane without additive) to 64.64% (membrane with 6 wt.% of additive). The enhancement of COD and colour removal rate from 61.50 % to 66.50 % and 78.75 % to 83.75 % was also observed in this study where the finding has signified the increased g-C3N4 nanoparticles concentration was constructive in PES membrane modification.
Changing the Paradigm of a Linear Economy into a Circular Economy in Residential Waste Management
Authors: Purwanto Edi , Prasetio Teguh
Published: December 2021

The purpose of this study was to find an effective and efficient way of managing urban household waste. The research method uses a case study. The data was taken from digital recording (Youtube) related to the residential waste management collaboration between Waste4Change and Gunas Land at Vida Bekasi. The research findings show that Waste4Change has implemented the circular economy principle in waste management in Vida Bekasi housing. The circular economy model carried out by Waste4Change in residential waste management should be used as a model for waste management in various other urban housing areas in Jakarta and other big cities.
Critical Insight into Defects in Malaysia Hospital Buildings Maintenance Management
Authors: Jesumoroti Christtestimony Oluwafemi , Cheen Khor Soo
Published: December 2021

Healthcare buildings require efficient maintenance management to afford patients, visitors, and other users of hospital buildings such as healthcare professionals a serene and safe environment that accelerates wellbeing and provides maximum comfort. To achieve this goal, hospital buildings must adopt effective maintenance management approaches and services. Apart from ensuring the safety of the environment, users of the buildings must be satisfied with the quality of available services, particularly, those offered to patients. Against this backdrop, this study assesses the effects of defects on hospital buildings and analyzes the practicality of maintenance best practices such as sufficient allocations of funds and appropriate management of resources (including time and labor) towards the improvement of the prevalent status quo. This is important because the maintenance practices employed in hospitals intrinsically impact the performance of the hospital buildings as a result of defects. Survey questionnaires were administered to users of hospital buildings in Malaysia. The most significant defects reported concerned Algae on concrete floors, weather and climate conditions, and sanitary appliance & fittings damages. These defects depreciate the appearance, functionality and utility of hospital buildings thereby lessening their performance and efficiency. Therefore, this study asserts the pertinence of reevaluating the maintenance management approaches employed towards the rectification of the highlighted defects in hospital buildings across Malaysia. The study posits the adoption of systemic proactive maintenance procedures to preempt decay, causalities and reduce cost implications.
Adsorption of Iron with Biosorbents derived from Longan Peel, Pomelo Peel and Jackfruit Peel
Authors: Chai Yi Jun , Ng Yee Sern , Shak Katrina Pui Yee , Ng Law Yong
Published: December 2021

High iron (Fe2+) concentration in groundwater is a severe issue in many regions of the world. This study attempts to investigate the effectiveness of biosorbents derived from longan peel (LP), pomelo peel (PP) and jackfruit peel (JP) for the adsorption of Fe2+ from aqueous solution in various forms. A batch adsorption study was carried out with an initial Fe2+ concentration of 10 mg/L for 2 h. The results showed that the highest removal efficiency was achieved for PP and its biochar at 97.38% and 99.45%, respectively. High removal efficiency implied that PP contained favourable characteristics for the adsorption of Fe2+. Under the scanning electron microscope (SEM), the surface structure of PP displayed visible dimensions with a relatively large pore size compared with LP and JP. Characterisation study using Fourier-transform infrared spectroscopy (FTIR) reveals that the carboxylate groups and ester carbonyl band participated in the adsorption process. At higher initial pH of 5.83, adsorption of Fe2+ using PP gives higher removal efficiency due to lower competition on electrostatic interaction between positive ions in the solution and the surface of biosorbents. Furthermore, adsorption uptake of 83.0 mg/g was attainable with an initial concentration of 100 mg/L. This study has proven the feasibility of PP as a low cost biosorbents for removing Fe2+ in an aqueous solution.
Optimization of compounding formulation for the development of high-preformance coating material using waste tire powder for gasket application
Authors: Siong Chai Kah , Muniyadi Mathialagan , Munusamy Yamuna
Published: December 2021

Nitrile butadiene rubber latex (NBRL) based gasket materials were extensively used in the past due to their excellent oil resistance, good abrasion resistance, and shock absorption as well as good high-temperature stability. Recently, carbon black has been introduced to further improve the oil absorption properties and thermal performance of the gasket materials which increased the total costing and makes the processing difficult due to the agglomeration of carbon black in NBRL. Thus, in this research, waste tire powder (WTP) was introduced to develop high-performance coating materials as an alternative to carbon black in NBRL gasket material. Optimization of new compounding formulation has been carried out by manipulating the WTP loading and hybrid WTP-carbon black filler loading. The filler loading was selected based on the desired surface texture and coating thickness. The experience was also carried out by varying the WTP, Sulphur, and plasticizer loading. The desired surface texture and thickness of coating materials were developed at WTP loading of 80phr and 90phr. Whereas, the optimum Sulphur loading was achieved at 1phr - 2phr, and plasticizer loading of 10phr and 15phr. From the experiments carried out, the optimum loading of WTP was 90phr which gives a fully contained gasket composite. Furthermore, DOP optimum loading is 15phr which gives a smooth surface appearance. Lastly, Sulphur with 1phr gives a more even surface texture as compared to 2phr loading.
Influence of Graphene Nanoplatelets on the Compressive and Split Tensile Strengths of Geopolymer Concrete
Authors: Ismail Fouad Ismail , Farhan Syed Ahmad , Husna Nadzhratul , Shafiq Nasir , Wahab MohaMohamed Mubarak Abdulmed , Razak Siti Nooriza Abd
Published: December 2021

Geopolymer is now a more advanced alternative to cement and available substitute for OPC while graphene nanoplatelets (GnP) are new nanomaterials with extraordinary properties that can enhance and improve the strength of cementitious materials. Although graphene reinforced concrete has intriguing potential, its implementation in construction requires better knowledge of the impact of GnP on the properties of concrete related to durability. Studies on the compressive and tensile strength performance of geopolymer concrete (GPC) containing GnP are needed. The present study investigated the influence of reinforcing GPC with varying percentages of GnP on the compressive and split tensile strengths of GPC. The addition of GnP ranged from 0.0%, 0.25% and 0.5% by weight of total binder. It has been observed that the addition of GnP increased the compressive strength by 30% and the tensile strength by 22% in comparison to a reference sample with a specified composition of fly ash and sodium metasilicate. In addition, the effect of GnP on enhancing the compressive strength of the geopolymer was shown to diminish as the amount of sodium metasilicate increased.
Effect of Granular Silica Aerogel as Filler on Tensile and Flexural Strengths and Moduli of Stone-Wool-Fibre-Reinforced Composite as Rigid Board Roof Insulation Material
Authors: Husna Nadzhratul , Farhan Syed Ahmad , Wahab Mohamed Mubarak Abdul , Wahab Mohamed Mubarak Abdul , Shafiq Nasir , Sharif Muhammad Taufiq , Razak Siti Nooriza Abd , Ismail Ismail Fouad
Published: December 2021

Installation of stone wool as thermal insulation in the roof assembly can be adopted to store heat in the living space, if the building is exposed to cold weather, and, inversely, to retard heat from entering the living space, if it is exposed to hot weather. In spite of the effectiveness of stone wool as a roof insulation material, during installation, it can cause irritation to the skin and can be hazardous to the lungs. Therefore, incorporation of stone wool with other materials to form a rigid board, without compromising its effectiveness as a roof insulation material, is imperative. Strength properties of a stone-wool-fibre-reinforced high-density polyethylene (HDPE) composite roof insulation material were studied. Granular silica aerogel, which possesses an ultra-low thermal conductivity, was added as filler to reduce the thermal conductivity of the composite. Hot compression moulding was performed to prepare samples of the composite with varying silica aerogel content of 0, 1, 2, 3, 4, and 5 wt. %. Findings suggest that 2 wt.% is the optimum silica aerogel content as it resulted in the highest flexural strength and modulus, which is 24.4 MPa and 845.85 MPa, respectively, even though it reduced the tensile strength and modulus by 10% and 4.45% respectively, relative to 0 wt. %, which can be considered as inconsequential. Higher silica aerogel content above 2 wt. % may result in poor interfacial adhesion and low compatibility to the stone wool fibre and HDPE, which further reduces the tensile and flexural strengths and moduli of the composite.
Property Correlations of Polypropylene based Composites Filled with Mimusop elengi Seed Shell Powder
Authors: Chien Tan Wuan , Muniyadi Mathialagan , Munusamy Yamuna
Published: December 2021

The saturation point of Mimusop elengi seed shell powder (MESSP) and the effect of MESSP addition on the mechanical, thermal, water absorption and morphological properties of polypropylene (PP) composites were studied. Tensile fracture, physio-mechanical properties and thermal behavior of composites were characterized using tensile and impact testing, thermogravimetric analysis, scanning electron micrograph, and differential scanning calorimetry. Processability of composites were feasible up to 20 wt. % MESSP by which agglomeration of MESSP and poor dispersion of MESSP in PP was observed above 20 wt% MESSP loading. Increasing MESSP loading showed tremendous improvement in tensile modulus and impact strength, whereas tensile strength and elongation at break were reduced. Water absorption and thermal decomposition of composites remain comparable with addition of MESSP up to 20 wt. %. Reduction of tensile strength was attributed by weak adhesion between MESSP and PP. However, morphological analysis revealed the presence of physical interaction via PP chain interlocking on MESSP surface.
The Preliminary Study for Effect of Plant Extract on Concentration of Heavy Metals in Soil
Authors: Lee Li Na , Guo Xinxin , Lim Jinq Shiou , Wong Rou Hui , Ng Choon Aun , Bashir Mohammed JK , Lee Lim Fang
Published: December 2021

Heavy metal contamination in soils had arisen into a more prominent problem as a result of increasing anthropogenic activities like manufacturing, mining, excessive application of agricultural chemicals and inappropriate disposal of wastes. Researchers across the globe had been striving to discover and develop methods to restore the soil back to its original condition with an assortment of remediation techniques that varies from treatment mechanism for various soil and contamination condition. Majority of the existing techniques have drawbacks like high energy consumption, specificity on the site condition, limitations on applicable contaminants, side effects after treatment, and also being uneconomical. More and more researchers are beginning to divert their attention into using organic stabilizers for treatment of soil heavy metal contamination in recent years after learning about its potential after numerous research showed promising reduction on the bioavailability and mobility of heavy metals. Due the lack of study on liquid-form organic stabilizers, the authors dedicated this research into implementing plant extract (TM) in the immobilization of heavy metals in soil. For comparison purpose, sodium alginate (SA), a proven organic stabilizer had been incorporated into the experiment to evaluate the performance of plant extract to immobilize cadmium (Cd), chromium (Cr), and manganese (Mn) from the metal-spiked soil samples in this research. The study findings suggested that the SA increased the unstable fractions, namely the exchangeable and carbonate fractions, of Cd relative to the untreated soil sample by 10.3 % to 5.2. On the other hand, the TM yields a result of 0.1 % to 1.1 % reduction of the unstable Cd. For the unstable Cr, both SA and TM decreased the concentration levels in the soil by 2.5 % to 8.0 % and 6.1 % to 7.9 % respectively. The results for Mn showed that the SA is able to decrease the concentration of its unstable fractions by 2.0 % to 7.5 % while the TM increases the concentration by 11.7 % to 1.5 %. In general, lower concentration of heavy metals in the unstable fractions was detected as the dosage of soil stabilizers applied increases. The application of soil stabilizers at 10 % weight percentage yields the lowest reading of unstable heavy metals in comparison with samples with lower dosage.
Fish Farm Wastewater Treatment using Moringa oleifera Seed Powder as Natural Coagulant
Authors: Tong Cheah Yi , Yusuf Fakhira Huda Binti Che , Derek CJC
Published: December 2021

In view of the huge amount of wastewater being generated from the aquaculture sector in Malaysia, Moringa oleifera seed powder was utilized as effective bio-coagulant to minimize the deterioration of fish farm wastewater quality. In this study, optimization of a coagulation-flocculation process was examined through response surface model toolkit established on a central composite design. A quadratic polynomial model was eventually selected to fit its turbidity removal response. The effect of four crucial parameters, namely pH, coagulant dosage, mixing time and settling time was optimized at pH 10, 400 mg/L coagulant dosage, 15 minutes mixing time and 10 minutes settling time for M. oleifera seed extract at a 47.11% turbidity removal efficiency. M. oleifera seed powder substantially removed (>30%) the concentration of total suspended solids, ammonia content, total volatile solids, and phosphate content as compared with the control group without any coagulant addition.
Floating Structure with Stabilised Buoyancy Control Device for Photovoltaic Application
Authors: Tan Chee Sean , Tan Lai Wai , Tan Chee Wayne
Published: December 2021

Conventional approach of energy derivation is causing anthropogenic pollution and climate change. Various sustainable alternatives of renewable energy particularly solar energy have been developed and implemented as a part of the global effort to gradually decommission usage of fossil fuel and in turn, reduce carbon footprint to overcome adverse environmental impacts. Nevertheless, it was reported that in 2019, only 0.85% of total energy used globally is powered by solar energy. Photovoltaic by itself is not feasible enough due to magnified requirement of land for its installation. Therefore, one of the solutions is floating photovoltaic. However, floating photovoltaic is also restraint by the impact of tidal wave. Characterisation of relationship between stability of large floating structures corresponding to volumetric displacement of the buoyancy control device is the focal point of this paper. Significance of tidal wave impact is empirically assessed based on a scaled-down model of buoyancy control device integrated large floating structure by manipulating the buoyancy of buoyancy control device assisted structure to structure without buoyancy control device under a controlled environment. Fluctuation of the buoyancy control device can be reduced by up to 99.65% when tested against highest configuration of wave transducer by displacing only 50% of air with water. Meanwhile, neutral buoyancy is achieved up to almost 100% when the buoyancy control device is completely filled with water and total submergence has been achieved.
Upgrading the fermentability and prebiotic potential of palm decanter cake through fibre-degrading enzymatic treatments
Authors: Teh Xiao Wen , Chang Ying Ping , Lee Kok Chang
Published: December 2021

Palm oil milling has produced tonnes of solid waste including palm decanter cake (PDC). The recalcitrant nature of PDC limits its full inclusion in animal feed. This study aims to investigate the effect of fibre-degrading enzyme such as cellulase and xylanase on the prebiotic activity and solid state fermentability of PDC. We used the following commercial enzyme loading: 5U cellulase (5UC), 5U xylanase (5UX) and combined enzymatic treatment 2.5U:2.5U (C25U) per gram of substrate to hydrolyse the defatted PDC. The sugar profile in the effluent was analysed by using high-performance liquid chromatography, and the degree of hydrolysis (DH) was estimated based on the total carbohydrates amount in the effluent. The DH of enzymatic-hydrolysed PDC followed the order of 5UC< C25U <5UX, which was 7.8 %, 44.2 2% and 46.27 %, respectively. The prebiotic activity score of ethanolic extract obtained from the PDC followed the order of untreated < C25U < 5UX < 5UC, which were -1.04, -0.74, -0.10 and 0.58, respectively. To further investigate the role of lignin (which can be eliminated through alkaline hydrogen peroxide treatment (AHPT) on the extent of hydrolysis and the fermentability of enzymatic-hydrolysed PDC, we tested the invasion capacity of fungus Aspergillus oryzae on untreated, and AHPT followed by enzymatic-treated PDC. Pre-treatment of PDC with AHP improved accessibility for enzymatic hydrolysis in which the highest fungus growth rate was observed on the AHP-C25U PDC. Enzymatic treatment succeeding AHPT is a feasible way to improve the fermentability of palm decanter cake.
Thermophysical parameters of the Kežmarok sandstone
Authors: Jaroš P , Vertal M
Published: December 2021

Thermophysical parameters of building materials are required for calculating the complex heat and water transfer in building structures. It can be performed by modern simulation software such as Wufi, Delphin, Math, Comsol Multiphysics and other. This software is suitable for evaluation of water and heat transport in construction of historical buildings, because it can include the impact of water on material properties, driven rain, ground water, heat and water accumulation and other. The material properties of historical building materials are required for the use of this software. In Slovakia, the most used building material was sandstone. Sandstone from Kežmarok was chosen for this paper, which was used in the construction of historic buildings such as churches and town houses. The method of dynamic impulse transition by thermophysical tester RTB was used to determine the thermal properties of sandstone.
Reverberation measurement set for the interrupted noise method
Authors: Jun D , Nespěšný O
Published: December 2021

This paper describes the methodology of measuring the sound absorption coefficient in a reverberation room. For its purpose, a measuring set was created combining professional with widely available hardware suitable for acoustic reverberation measurements. For the measurement itself, the interrupted noise method was chosen based on the standard ČSN EN ISO 354. Measurement and evaluation of data take place using scripts written in the Python programming language. An effective measuring set was developed both in terms of operation during measurement and in terms of subsequent data processing, accessing and graphical presentation.
Advanced building materials - prefabricated and modular designs as part of Construction 4.0 with a focus on transport constructions
Authors: Krupík P
Published: December 2021

Digital and technological innovations that have grown rapidly in recent years have been referred to as the 4th Industrial Revolution or Industry 4.0. The paper comprehensively deals with the description of the Advanced building materials, Prefabricated and modular designs as part of Construction 4.0 with a focus on transport construction. The aim of the article is description of this issue comprehensively and with the help of SWOT analysis identify weaknesses, strengths, opportunities and threats with focus on the transport constructions. The content is complemented by an assessment of the current situation, indicating the possibility of use in practice.
Analysis of time consumption for extensive green roof realization
Authors: Hejl M , Mohapl M , Jílek J
Published: December 2021

The article deals with the analysis of time consumption for the construction of an extensive green roof. Also, it deals with the construction of several extensive roofs in terms of time and then sets a new standard hour for the construction of an extensive green roof. At the end of the article, it is said how it would be possible to speed up the construction of extensive roofs or in some cases simplify it.
Alternatives how to mitigate urban flooding and CSO in urbanized areas used in European cities and towns
Authors: Csóka M , Rózsa G , Marko I , Stanko Š
Published: December 2021

Urban flooding and combined sewer overflow in city, or town areas represents potential risk in environmental, economic, or social aspects. The goal of this study is to process and evaluate efficiency of individual solutions to reduce occurrence of flooding in urban areas caused by intense rainfall events. The known conventional solutions are stormwater chambers, or storage drains. The new trend in reduction of stormwater drainage into combined sewer system are parts of blue-green infrastructure. Blue-green infrastructure represents environmental urban infrastructure which consists of sensitively selected urban vegetation combined with ingenious hydrological elements of urban city drainage. The study also deals with experimental usage of decentralized real time control, based on a gossip-based algorithm of moveable gates in sewage network. Experiment was proposed for drainage system of the city of Cosenza in Italy. Evaluation will assess application value of individual proposed solutions for the reduction of combined sewer overflow for Slovak republic and its urban cities, or towns.
Analysis of CO2 emissions in municipality Most pri Bratislave
Authors: Garaj M , Zeleňaková M
Published: December 2021

The most discussed topics in the 21st century at the global level are climate change, carbon neutrality, digitization and globalization. They have impact on the lives of all people, the quality of the environment in which we live, the health of the whole population, the development of cities and urban areas, the development and direction of industry and its new technologies, and last but not least, they shape humanity to which they are giving direction. To meet our 2030 goals, we need to know where we are now from carbon footprint point of view and where CO2 production comes from around us.
Combined sewer overflow chamber analysis based on CFD modelling.
Authors: Hrudka J , Šutúš M , Csóka M , Raczková A , Škultétyová I
Published: December 2021

The paper deals with CFD simulation of a real combined sewer overflow chamber using Ansys fluent software. Simulations are created for various structural modifications. Within the results, the hydraulic parameters of the individual are evaluated with a proposal for optimal operation of the given relief chamber.
Single-step and double-step heath recuperation of waste water from thermal baths
Authors: Predajnianska A , Takacs J
Published: December 2021

Thermal baths in Slovakia are producers of wastewater, which hides considerable energy potential. The wastewater from the thermal pools has often exceeds the maximum permissible value of the temperature of the wastewater discharged into the water recipient. As a result, there is undesirable damage to the environment, which results in sanctions for the operators of these facilities. Our aim is to present the concept of a single- and double-step heat recuperation system of waste pool water using applications of various types of heat exchangers or heat pumps. The aim of this application is to ensure a suitable temperature to the discharged waste pool water, efficient use of the energy potential of the waste water and saving of primary energy in the form of geothermal water, thus extending the life of the entire system.
Development of the level of sorting of municipal waste in the selected locality
Authors: Rózsa G , Wittmanová R , Hrudka J , Škultétyová I
Published: December 2021

Waste management is one of the essential areas that everyone in the world should carry about. Waste collection and treatment help to reduce the risk of the spread of various diseases. Municipal waste is waste produced in households by the population. Municipal waste can be sorted into other components, such as plastic, paper, glass, metals, and biodegradable waste. These types of waste are in most urbanized areas collected separately. The sorting level offers accurate information about each urbanization, to what extent its population is involved in separated waste collection. The paper focuses on analyzing the waste collection system in the selected locality and will examine the local waste sorting level development during the last few years.
Flood risk assessment methodology
Authors: Šugareková M
Published: December 2021

Paper presents a proposal of the flood risk assessment methodology. The theoretical background is based on the multi-index conceptual models, which consists of three layers -objective layer, index layer and indicators layer. The fulfilment of the layer is based on the Reports on the course and consequences of floods in the territory of the Slovak Republic.
Development of design rainfalls: A review
Authors: Wittmanová R , Marko I , Šutúš M , Stanko Š
Published: December 2021

Design rainfalls are essential parameters in designing and assessing combined and stormwater sewers and are still used today. They create idealized intensity profiles with statistically determined parameters. Their gradual development is based on the development of computer technology, measuring instruments, and measurement campaigns’ progress. However, climate change is causing changes in precipitation events’ characteristics, so it is important to focus on reassessing them and adapting to current conditions. The paper summarizes the knowledge about the development of design rains to reveal their potential for the future.
Silicate conductive composites with graphite-based fillers
Authors: Baránek Š , Černý V , Yakovlev G , Drochytka R
Published: December 2021

Electroconductive composites are modern materials that are commonly used in many industries such as construction industry and machine-building industry. For example, these materials can be useful as sensors for monitoring changes in constructions, shielding stray currents from electrification networks, shielding electromagnetic radiation in operating rooms, cathodic protection against moisture or overvoltage protection of buildings. The topic of this post is the research of electrically conductive silicate composites with graphite-based fillers. In this research will be tested composites with different ratio and types of graphite and monitor their electroconductive properties like impedance, and physical-mechanical properties like compressive and tensile strength. The post describes basic properties and interactions of silicate electrically conductive composites with graphite fillers. It was found that by adding 10 % wt. graphite into silicate composites, impedance is reduced by 50% and compressive strength by 40%. The flexural tensile strength depends mainly on the roughness of the particles, where the coarser flaky particles transfer the load better and increase the strength while very fine graphites reduce the flexural tensile strength. Furthermore, it has been found that very finely ground synthetic graphites are most suitable for achieving low impedance of composites.
Impact of dampness to changes in the mechanical properties of solid fired bricks
Authors: Bartoň V , Šnédar J , Cikrle P
Published: December 2021

This work deals with the monitoring of changes in the mechanical properties of solid fired bricks depending on their dampness using non-destructive methods. Decreases of first natural frequencies by the resonance method and increase of passage times of ultrasonic waves depending on increasing dampness are monitored. The elements were firstly fully saturated and then slowly dried so that it was possible to record the values of the first natural frequencies and the passage times of the ultrasonic waves at different dampness. It is not possible to record values in all dampness, so the measured values were interpolated by regression models. A polynomial of the 2nd degree seems to be the most suitable. Dampness corresponding to the minimum natural frequencies and the maximum passage times of the ultrasonic waves were performed on these regression models. This research is the first step in determining the durability criteria for ceramic products, especially solid fired bricks. In the future, durability criteria should help in the reconstruction of historic buildings to assess whether the element that will be exposed to the weather is durable or not. These tests are completely non-destructive, which means that the tested element can be subsequently used in construction.
Study of polymer-based adhesive mortar with higher durability
Authors: Hermann R , Figala P , Mészárosová L , Drochytka R
Published: December 2021

This paper deals with the study and development of polymer-based adhesive with high filling ratio of secondary raw materials and waste materials. The goal of this paper is to develop adhesive mortar with the highest filling rate of secondary raw materials and waste materials as possible while preserving very high physical-mechanical properties, including flexural and compressive strength, pull-off bond strength and abrasion resistance. High-temperature fly ash, waste slag and waste packaging glass are used in this paper as fillers. The resulting mortar shows high physical-mechanical properties, including high abrasive resistance and very high bonding strength to a large variety of building materials including concrete, steel, glass, and tiles.
Overview of the presence of predominant microorganisms on the interface of cementitious materials and soil from selected locations
Authors: Hološová M , Eštoková A , Luptáková A
Published: December 2021

The presented work focuses on the predominant microorganisms on the interface of cementitious materials and soils from different localities. Soils contain microorganisms that can affect the underground concrete structure positively or negatively. Different types of microorganisms are adapted to the environmental conditions depending on the quality and quantity of elements in the soil. Methodology of the work was based on screening 5 selected localities in the Košice city from which soil was taken in the nearness and in the contact with the concrete structure. These samples were further analysed. In this paper the presence of bacteria in the soil around the construction is confirmed.
Analysis of the behaviour of 3D samples printed by FFF/FDM technologies under bending stress with a focus on infill
Authors: Juračka D , Kawulok M
Published: December 2021

The focus of this paper is to explore the possibilities of optimizing 3D printed elements produced by FFF/FDM technology based on bending tests according to ČSN EN ISO 178 (64 0607) with variations in the settings of the printing itself. The principle of FFF/FDM is the printing of a continuous fiber made of thermoplastic material, which is applied by machine to the previously printed fiber. There are many combinations of possible print settings, and one of them is the geometry of the inner density with variable density. Their resulting maximum values of the achieved load were then compared with the weight (amount of material used) and printing time. The result is a comparison to achieve economical printing with the greatest possible load capacity.
Influence of fly ash addition on physical-mechanical properties of clay bricks – literature review
Authors: Vrdoljak I
Published: December 2021

During the past years, due to the increase in the number of people and the increasing degree of industrialization, the amount of by-products produced, the so-called waste materials are becoming larger. As this problem grows with age, attempts are being made to find answers to the questions of how to use waste material purposefully in order to reduce the problem of disposing of large quantities of this type of material. One way to reduce the accumulation of waste material is to use it in construction materials. This literature review paper presents the research of the area dealing with the influence of fly ash application on properties of clay brick. The application of fly ash at various percentages in relation to the mass of clay and the influence of fly ash at different firing temperatures are studied.
Methods of calculation of cold-formed structures
Authors: Hodovanets E , Al Ali M , Kvocak V
Published: December 2021

Cold-formed structures are a separate type of metal structures and require more complex mathematical models in comparison with massive profiles. The development of main theories was described. A new type of buckling is also taken into account - warping, which is characteristic only of cold-formed bars.
Numerical analysis of asymmetrical using of actuators to membrane structure
Authors: Kapolka L , Stulerova L
Published: December 2021

This paper is focused on the numerical analysis of an adaptive membrane structure, the model of which was created on the basis of experimental device in the lab. It was researched out the effect of asymmetric use of actuators on the membrane structure without structural loads. Results of the article describe the behaviour of numerical model. The results gained from numerical model will be compared in the future with the results measured out from the experimental device.
Crack behaviour at the interface of a surface layer applied on a steel substrate by laser cladding
Authors: Malíková L , Doubek P , Miarka P , Seitl S
Published: December 2021

An influence of the bi-material interface between a steel substrate and a thin protective layer applied through laser cladding was investigated. A range of elastic properties and thicknesses of the layer were considered to cover the behaviour of a short crack in the selected materials such as bronze, nickel or cobalt alloys. The special case of the crack terminating directly at the interface was investigated, which is connected to the necessity of application of generalized approaches of linear elastic fracture mechanics. The results contribute to better understanding of fracture response of selected materials and to a more reliable decision on choosing a proper material of the protective layer.
Evaluation of dynamic behaviour of an experimentally tested model on a shaking table
Authors: Taušan D , Brandis A , Kraus I
Published: December 2021

The usual structural analysis assumes that buildings are fixed to the ground. This is not always the case, especially for structures with shallow foundations on soft soils. It was learned from the literature review that neglecting soil compliance in the structural analysis may result in significant structural damage during an earthquake event. The seismic performance can greatly differ between buildings rigidly fixed to the ground and buildings for which soil compliance is considered. Therefore, the main goal of the experiment conducted in the laboratory of the Faculty of Civil Engineering in Rijeka was to observe the dynamic behaviour of a structure on soft soil. The model was experimentally tested using a shaking table. The foundation soil was modelled using local river sand. For parametric analysis, a numerical model was done using the computer software SAP2000. The model was calibrated using experimentally obtained results. A comparison between the experimental and numerical models is presented in the paper.
Comparison of the level of required prestressing of road bridges according to the historical development of technical standards in Slovakia
Authors: Baran J , Borzovič V
Published: December 2021

The paper deals with the level of required prestressing designed for box-girder bridges. Mainly focuses on the development of standards used in the design of prestressed concrete road bridges in the Slovak Republic. The standards for bridge design have been amended several times. A parametric study was performed on a model post-tensioned concrete bridge with a box-girder cross-section. The bridge has three-span with a main span of 50 m and end spans of 40 m. The study compares the normal stresses caused by traffic load along the length of the bridge according to various standards and technical regulations. The differences in design principles were investigated while the amount and geometry of the longitudinal prestressing of the bridge were changed as required by corresponding standards. The numerical model is considered as a beam element with neglecting of the torsional effects of the load. The parametric study points out the differences in the normal stresses along the bridge according to different design regulations and standards. The aim of the study is to compare level of prestressing according to the historical development of prestressed bridges
Strengthening flat slabs without shear reinforcement against punching shear by concrete overlay
Authors: Čereš D , Gajdošová K
Published: December 2021

Research in this paper presents a theoretical study of increasing in punching shear capacity of the strengthened flat slab by concrete overlay. The parametric study is based on comparison of three different relevant standards design models and presents results how Eurocode 2 (EN 1992-1-1), Model Code 2010 and draft of second generation of Eurocode 2 (prEN 1992-1-1) take into account strengthening by concrete overlay. A reference specimen is represented by a fragment of a flat slab supported by circular column. Influence of concrete toppings depends on thickness and also on reinforcement ratio. In Eurocode 2 and new generation of Eurocode 2 the increase of punching shear resistance of the slab with concrete topping can be taken into account only by reinforcement ratio and thickness of the slab considering the perfect connection and bond between the original slab and new layer of concrete overlay. Model Code 2010 is based on Critical shear crack theory and the reinforcement ratio in concrete topping was considered in equation of moment of resistance and punching shear resistance is calculated by considering the rotation and deformation of the slab. Estimation of results by parametric study are compared by non-linear model from Atena software.
Theoretical research of dimensional optimization and choice of material strength in steel-concrete composite beams
Authors: Hrabovska K , Brecka J
Published: December 2021

The aim of this study is to find out how the change of individual parameters will affect the flexural strength of steel-concrete composite beams. The project was focused on the choice of strength of materials and the choice of dimension, specifically the height of the concrete slab and the size of the steel profile. The research aim is to reveal which parameters have dominant influence on the flexural strength and thus facilitate the optimization of the design in practice.
Determination of temperature gradient of slender structure
Authors: Velešík M , Požár M , Nečas R
Published: December 2021

This study investigates convenient methods of determination of temperature gradient of slender structures in time. Correct determination of temperature along the height of the cross-section takes a key role in defining the temperature loading of slender bridge structures. A proper definition of temperature loading is crucial for structures such as stress ribbon because of their sensitivity to temperature change in terms of geometrical changes of the structure. Correct determination of the temperature gradient is important during long-term geodetic monitoring, which might be used to prove the correctness of computational models of bridge structures. To approximate heat transfer in cross-section, a test specimen with temperature sensors installed along the height was formed and continuously monitored. The accuracy of the retrofitted temperature sensors was also investigated. The temperature at the surface of the specimen, solar radiation and wind velocity were used as input data for heat transfer analysis. The measured values from sensors situated along the height were subsequently used for verification of performed heat transfer analysis on volume computational model in the software Ansys Mechanical.
Analysis of anomalies in the control probes of the Rozgrund dam
Authors: Koval F
Published: December 2021

The subject of the contribution is to clarify the causes of anomalous development of water levels in some observation objects of the Rozgrund dam. To clarify the anomalous development of the water levels, a detailed analysis of the development of water levels in all observation probes built on the dam, the water levels in the reservoir and the daily total precipitation was performed. An important knowledge is the amplitudes of fluctuations in water levels in observation probes and in the water levels in the reservoir. The calculations of correlation coefficient, expressing the relationship between water level in individual boreholes and the water level in the reservoir are another step in assessment of anomalies. Based on the knowledge obtained, it was possible to assess the degree of the influence of the water level in the reservoir on the development of the water level regime in observation objects. At the same time, it was also possible to detect the existence of other effects influenced the water levels in the probes, such as the leakage into their surroundings caused by precipitation or the impact of waters flowing from hillslopes.
Designing the sewerage network of the city in purpose to reduce impact to the environment and water bodies
Authors: Portnov M , Popov A , Hrudka J , Stanko S
Published: December 2021

Today, the study of the city’s sewerage network is an important part of the life of the city and the environment. Ensuring optimal living conditions not only for oneself, but also for other participants in the environment should be a priority for a person. Today we can face various problems that complicate the operation of the city sewer network and can cause detrimental effects on the environment. To prevent this impact on the environment, you first need to understand the cause of this impact, and then look for a solution. Wastewater is a pollutant of rivers, lakes and the water system in general. Wastewater is formed in connection with human activity, the appearance of rainwater, as well as under the influence of industrial enterprises. The purpose of the article is to develop the management of wastewater flows within the city sewer network to ensure the highest quality water clarification and minimize environmental harm.
Restoration of a wetland Čéne in eastern Slovakia
Authors: Repel A
Published: December 2021

The aim of this paper is to present the possibility of revitalizing the disappearing wetland of Céne in eastern Slovakia. Due to climate change and anthropogenic interventions in the natural landscape, natural habitats are currently extinct. Wetlands are one such habitat, of which the Céne wetland is a very good example. Wetland Céne is a place of occurrence of rare species of fauna and flora. The paper proposes and evaluates the method of revitalization of the wetland by subsidizing the water in the wetland from the river Tisa through the proposed dam culvert. The paper also evaluates the technical measures that need to be implemented and the economic aspects of this solution.
PMMA direct exfoliation for rapid and organic free transfer of centimeter-scale CVD graphene
Authors: Zhao Hewei , Xing Xianqin , Zhang Gehui , Liu Wenyu , Dong Haoyu , Lu Zhanjie , Li Tianyuan , Zhang Junfeng , Cheng Zhihai , Wang Le , Chen Shanshan
Published: December 2021

Despite the various techniques developed for the transfer of large area graphene grown by chemical vapor deposition (CVD), the conventional polymethylmethacrylate (PMMA) transferring technique has been widely applied in laboratories due to its convenience and economical cost. However, the complete removal of PMMA on graphene surface has become a troublesome, and the PMMA residue could degrade the properties of graphene significantly. We report here a facile water assisted technique to directly peel off the PMMA layer over centimeter-sized CVD graphene film for the first time. No organic solvents are involved in the whole transfer process. The transferred graphene film is clean and intact over large area because of the cooperative effect of the capillary force and the van der Waals force which facilitates the conformal contact between graphene film and the substrate. Various types of graphene samples (i.e. monolayer, multilayer, and incomplete domains) can be easily transferred to diverse substrates including silicon wafer, sapphire, and quartz with good integrity. The transferred graphene film is of high cleanliness, and the graphene transistors show higher carrier mobility and lower level of p-type doping comparing to the conventional wet transfer technique.
Have mysterious topological valley currents been observed in graphene superlattices?
Authors: Roche Stephan , Power Stephen R , Nikolić Branislav K , García José Hugo , Jauho Antti-Pekka
Published: December 2021

We provide a critical discussion concerning the claim of topological valley currents, driven by a global Berry curvature and valley Hall effect proposed in recent literature. After pointing out a major inconsistency of the theoretical scenario proposed to interpret giant nonlocal resistance, we discuss various possible alternative explanations and open directions of research to solve the mystery of nonlocal transport in graphene superlattices.