Modern Building Materials, Structures and Techniques

This manuscript represents a historical influence of Gediminas Hill constructions and buildings for nowadays condition. According to latest investigations realized in 2019–2020 and obtained results, it was prepared three-dimensional numerical model. In this model it is included Gediminas Hill geological profiles with geotechnical parameters and Gediminas Castle remains (including pedestrian path, tunnels, funicular, etc.). Due to a very large computational resources necessity simulations realized in a private Vilnius Gediminas Technical University cloud. Created numerical model allows to simulate nowadays problems, mainly – slope stability. Gediminas Hill slope stability is lowest at the slope surfaces, where is the thickest technogenic soil layers. According to the shape and size of possible landslides formations, landslides assigned to shallow local landslides. Updated in-situ investigation results are used in the numerical model and it allows to simulate various environmental conditions which are affecting slopes stability and, in some case, can make influence for Gediminas Castel remains.

The fib WP 2.4.1 is a technical committee of the fib organization ( https://www.fib-international.org/commissions/com2-analysis-design.html ) dedicated to the development of methodologies for the design of fibre reinforced concrete (FRC) structures using computer programs based, mainly, on the finite element method (FEM). For taking advantage of the fibre reinforcement, these computer programs should simulate the relevant fibre resisting mechanisms, mainly the ones that increase the post-cracking tensile capacity of cement-based materials. Several challenges are, however, faced for assuring reliable simulations, namely: 1) the knowledge of the stress-crack opening simulating correctly the post-cracking tensile behaviour of the FRC of the structure to be designed; 2) modelling the contribution of fibre reinforcement in structures failing in shear, punching or torsion; 3) level of accuracy of these models on performing the serviceability and ultimate limit state design verifications; 4) guarantee results independent of the refinement of the finite element mesh; 5) design format (characteristic, average or design values for the material properties). To contribute for a proper handling of some of these challenges, the fib WP 2.4.1 has been coordinating a series of blind simulation competitions, whose relevant objectives and results are described in this paper. The vison on the use of this information for deriving information useful in the design of FRC structures is also provided.

This article focuses on the serious time bound attempts of getting zero emissions for circular sustainability. It requires an all-encompassing strategy that prioritizes people, the planet, and profit. To achieve climate neutrality, nanotechnology is essential because it promotes the creation of cutting-edge, potentially game-changing technologies that have no negative effects on biodiversity and ecosystems. Nanotechnology is becoming increasingly environmentally friendly as the field turns its attention to renewable energy, waste diversion, digitalization, sustainable building construction, and structural engineering. Considering the United Nations Sustainable Development Goals and the European Green Deal, this article outlines essential steps towards reaching carbon neutrality. The transition to a sustainable future can be speed up if there is cooperation among local wisdom, businesses, and governments. Intelligent gadgets and building blocks have emerged as a central topic due to recent developments in nanotechnology. The paper emphasizes the potential of nanotechnology to generate innovation and sustainability and the importance of collaboration between different stakeholders.

In steel construction, non-uniform heating caused by welding during fabrication is unavoidable. This is how residual welding stresses and deformations occur. The processing conditions result in important differences in residual stress distribution and magnitude. In the paper the structural relevance will be analyzed by tests and simulations. The residual stresses have been measured by the use of a mobile X-Ray diffractometer. The thermomechanical analysis was carried out by a 2D model, the mechanical analysis by a 3D model. Case studies concern the buckling of compression members, single-side and double-side welding concerning lateral-torsional buckling of beams and full and partial stiffeners in welded knee joints. Residual stresses can also be important when straightening steel members. This is shown on an unregular longitudinal stiffened box girder.

The respective key-note presentation will highlight the results recently obtained by the research group on predicting the serviceability behaviour of RC members. The presentation will consist of three main parts: 1) A new bond-slip model. 2) A new deflection model for concrete bending members reinforced with steel or FRP bars and steel fibres. 3) A novel crack model termed the Strain Compliance Crack (SCC) model. The current paper will be limited to the description of the latter crack model. It accounts for the specifics of primary and secondary crack spacing and width analyses in RC beams, as demonstrated by testing. The reinforcement strain profile is used to predict crack spacing, which is the primary emphasis of the model. The model includes a novel concept of the limit effective depth, dlim, to classify crack types. For small beams (d ≤ dlim), only primary bending cracks are examined, whereas secondary cracks are addressed for large beams (d > dlim). Parameter dlim is influenced by the reinforcement ratio, modular ratio, cover, and bar diameter. Although the model may estimate the mean spacing between primary and secondary cracks, only primary cracks are used for calculating crack width. For small beams, the crack width profile is a straight line. It is presumed that the width profile of major cracks in large beams is bilinear (including fish-shaped). The proposed model accurately predicted crack spacing and width, which corresponded with experimental findings.

The creation of a defined surface morphology of components plays an important role in many technical applications like reduction of friction and wear or change of the adhesion of particles. In this contribution, a surface treatment process for the precise modification of the surface topology was developed on the basis of the cold spray technology. In this process, fine particles are accelerated in a gas stream by a Laval nozzle to supersonic velocities and sprayed on the surface. The particles can be embedded into the substrate surface by impact forming hills or rebound from the surface forming a crater-like surface. The influence of the process parameters on the microstructure formation was studied for fine steel and titanium particles colliding on the steel and titanium surfaces by experiments and numerical simulations. The particle acceleration in the Laval nozzle and the jet was simulated by Computational Fluid Dynamics and measured with high-speed Particle Image Velocimetry. The deposition of particles was described by a model for the critical impact velocity. The mechanical properties of surfaces and particles were measured by high temperature nanoindentation method and used for the determination of the regime diagram of the process.

The performance of FRP-bonded concrete is heavily influenced by the properties of the bond between the two materials. Various bond-slip models incorporating interfacial bond properties have been developed to understand and predict this behaviour. In a bond-slip model, the interfacial bond properties are specified in terms of the bond shear stress at the interface and the associated slip or interfacial fracture toughness (energy). Therefore, it is crucial to determine the sensitivity of these properties to the structural response, as it affects the prediction of FRP-bonded test samples and debonding failure modes. This study investigates the sensitivities of interfacial bond-slip properties using a bond-slip model comprising ascending and descending curves. The results indicate that the interfacial fracture energy significantly affects the maximum load resistance, while the ascending curve has a substantial impact on the effective bond length. These findings shed light on the importance of interfacial bond properties in determining the performance and behaviour of FRP-bonded concrete structures.

Crystalline admixtures are often used as waterproofing agents added in the concrete mixture and have the capability of promoting self-healing of concrete. Sika WT-200 P is one of the examples of crystalline admixture typically used at 0.8–2% by cement mass. In this paper, concrete test specimens containing crystalline admixture were cracked using two methods and exposed to different environmental conditions then analysed for crack healing ability using image analysis done through in-house code. Self-healing is visible within the first 7 days of hardening in the test specimens immersed fully in water. After 100 days, images are taken using a Canon camera. The images are converted into grayscale then binary images are produced which show that self-healing has occurred, and the average crack width has been reduced by as much as 90% in some cases. The compressive strength of these specimens is as high as 90 MPa beyond 100 days of self-healing tests.

Nuclear energy has several difficulties connected to the production or storage of the radioactive waste. Long-term operation is a process that may prolong the serviceability of the power plant by 10, 20 or more years. Nevertheless, crucial components as the reactor pressure vessel or its surrounding must be proved before enabling this process.Fast-neutron radiation can have several effects on the concrete biological shield around a nuclear reactor. It can cause changes in the lattice structure of some rock forming minerals, resulting in an increase in volume of several percent and this may lead to cracks between the hardened cement paste and the coarse aggregate grain. Fast neutron radiation is converted in concrete to thermal neutrons which generate secondary gamma radiation and heat whereas gamma generates heat as well. Heat followed by drying causes additional shrinkage of the hardened cement paste. All these affects can be observed via digital images processing after the images have been subjected to segmentation, pre-processing, registration and normalization of the illumination.Twelve small holes were drilled in the concrete slab 50 × 50 × 5 cm and the resulting cores of a diameter 4 cm were removed. They were cleaned and polished then inserted into the LVR-15 Research Nuclear Reactor for one year of irradiation with exposure to a flux of 6 ÷ 7 × 1011 neutrons·cm−2s−1.The samples were measured and photographed using the Vertex measuring system before and after irradiation and they were examined to find evidence of any visual changes. The work on digital image processing began in April 2023 and the first outcomes should be available at the end of the year 2023.

Layered concrete structures provide many benefits in construction of a new project and repair, strengthening of already existing structures. However, this type of structural member has a vulnerable point, which is the interface between the layers. If the stiffness of the interface between the layers is not sufficient, the structure might fail at the interface and the layers might slip relative to each other. Interface behaviour is a complex process, which is yet to be fully understood. This article presents a theoretical method for analysing the behaviour of the interface. Using this method, an analysis of experimentally tested specimens, which were tested by other authors, was conducted. After the results of the analysis, it was confirmed that the proposed theoretic method is an appropriate tool for analysing the interface. Additionally, a parametric analysis was carried out by changing the values of concrete strength and connector ratio. Lastly, using the determined values of shear stress and slippage, a shear stress modulus for experimental specimens was calculated.

Timber-concrete composite (TCC) structures consist of timber beams, a concrete slab and shear connectors. Normally, shear connectors provide a flexible bond between the timber beams and the concrete slab resulting in a composite member. Main applications of such structures are TCC slabs, whereas walls and other elements have been executed only in few cases as TCC member. It is well-known that the shear connectors are of high importance for the load-bearing behavior of TCC slabs. Therefore, many research projects have been carried out aiming on the development and optimization of suitable shear connectors. In contrast, there are only few investigations on the required mechanical properties of the concrete slab.At begin, the paper reports the general structure of TCC slabs, the consequences of flexible bond, and legal situation when applying TCC. In the following, typical loading conditions of concrete slabs as part of a TCC structure is considered. In longitudinal direction, that means in parallel to the timber beams, the section of the concrete slab is mainly under compression. The height of the tensile zone is limited to few millimeters or centimeters. Thus, the application of a conventional steel bar or mesh reinforcement is not useful. Because of needed concrete cover it is impossible to arrange the steel reinforcement within the tensile zone. Alternative solutions, e.g., steel fiber reinforced concrete and textile reinforced are more promising. The paper investigates the concrete slab design when using steel fiber reinforced concrete and textile reinforced concrete.

The European Green Deal poses ambitious challenges for the construction industry in general. It is necessary to develop building materials that enable the design of more environmentally friendly and sustainable buildings and construction processes in general. Lightweight concretes offer the potential to tackle several requested improvements for the precast industry and conventional construction. The addition of low-density aggregates allows the design of concretes with good thermal insulation properties and low weight. However, conventional lightweight aggregates and recipes developments usually result in concretes with low compressive strengths. With the help of perlites produced in electric furnaces, it was possible to develop high-strength lightweight concretes with compressive strengths of normal concretes in the course of an accelerated recipe development process. The formulations led to a selection of lightweight concretes which, compared to high-performance aerogel lightweight concretes, achieved strength increases of up to 100% at a comparable dry density. Initial simplified fire tests also showed positive results in terms of fire behavior and thermal conductivity. The measurement results of a thermal imaging camera in the single flame test show benevolent behavior under direct flame exposure.

Fibre-reinforced polymer (FRP) as an alternative reinforcement material offers the major advantage of being corrosion-free compared to conventional steel reinforcement. However, FRP has lower elastic modulus than steel and thus concerns in serviceability performance may arise. In the structural design of FRP-reinforced concrete (FRP-RC) flexural members, the deflections under serviceability limit state should be checked against relevant deflection limits. This study focuses on the analysis of flexural response of FRP-RC beams taking into account the tension stiffening phenomenon by way of the parametrized tensile stress block (TSB). For prediction of deflections, a parametrized TSB is proposed for application in combination with nonlinear multilevel member analysis, where the analysis is performed first at sectional level and then at member level to account for the nonlinear response of cracked structural elements. Three FRP-RC beams tested in the literature are analyzed, and the good agreement between experimental and analytical results verifies the applicability and accuracy of the proposed parametrized TSB.

Rectangular hollow section (RHS) profiles gained leading positions in various structural applications mainly because of their aesthetic appearance and structural integrity, ensuring efficient utilization of steel. In addition, the lightweight of the profiles and high resistance to torsion simplify manufacturing and building processes. However, reducing the weight makes such elements susceptible to undesired premature buckling when a structure loses its stability at the loading well below the theoretical strength limit of the material. Despite years of design practice, the above problem limits the further decrease of the RHS thickness. This study considers an alternative approach employing a low-density polymeric insert to ensure the local load-bearing capacity of the RHS fragment. The results of the 100 mm long fragment of the slender RHS 200/100/4 (height/width/thickness) profile compressive tests provide the adequacy of the numerical (finite element) model used for assessing the mechanical efficiency of the proposed strengthening concept. The 3D printing technology offered the 10% density and precise geometry of the polymeric insert that increased the weight of the RHS fragment by only 28%. At the same time, the mechanical resistance of the hybrid cross-section increased two times regarding the reference (non-strengthened) RHS sample. This effect corresponds to the profile thickness increase from 4 mm to 6 mm, i.e., 1.5 times increasing the profile weight. The possibility of using recycled plastics for strengthening purposes increases the economic effect of the proposed concept.

This study presents two methods for analyzing the ultimate load capacity of a multi-story steel frame structure with geometric imperfections and material nonlinearities. The first method is in accordance with European standard (EC) for steel structures, based on which the initial geometrical imperfections (out-of-straightness and out-of-plumb) are determined. In the second method, the first order reliability method (FORM) is utilized in order to determine the ultimate design resistance. In this second approach, the initial geometrical imperfections are based on European standard for allowed manufacturer tolerances, and are considered as statistical parameters. Local bow-imperfection amplitudes of each column (in both directions), global sways of each floor (in two directions), as well as material elastic modulus and yield stress are considered as stochastic variables (together 80 random input parameters). Cumulative tolerances of each story position are monitored and random realizations which violate these tolerances are distinguished. The results of both methods are summarized and compared in the matter of the ultimate resistances: design value according to EC vs. 0.1% quantile of stochastic ultimate resistance out of the FORM method. Failure modes of the random realizations are discussed as well. Overall, both methods resulted in comparable values of the ultimate resistances, with the design value based on EC standard being slightly more conservative then the value based on the FORM method.

The article presents a new approach for modelling initial geometric imperfections as a linear combination of scaled buckling modes obtained from elastic buckling analysis. The scale of buckling modes is calculated using Shannon entropy and potential energy. The presented case study shows that the first buckling mode is dominant, and the scale of the other buckling modes decreases. The entropy calculated from deformation presents a new perspective on buckling modes. Entropy makes distinguishing the non-sway (symmetric) and sway (antisymmetric) buckling modes possible, which is valuable if the critical loads of non-sway and sway buckling modes are close or coincide. Coupling the entropy with the potential energy of the buckling modes provides a deeper insight into the behaviour of steel frames. This proposed methodology, incorporating entropy and potential energy, offers a new and promising approach for designing structurally robust and buckling-resistant systems, empowering engineers to optimize the performance and reliability of steel frames.

This paper deals with modelling of steel-concrete-steel sandwich structure by FEM plane elements. In the introduction a brief description of a steel-concrete-steel sandwich structure is presented together with author´s motivation to deal with this type of a structure and its modelling. Current design approaches of steel-concrete-steel structure are also briefly mentioned. The following part of the article present a general description of two eventual modeling methods, including overview of advantages and disadvantages. One of the mentioned methods is based on effective stiffness without any need to divide the model into layers. The other one is based on physical layering of plane elements. The next part of the article is focused on the implementation of the presented methods using helpful tools, that may significantly reduce time of a modelling process. In the end, a short example of use of the presented methods is shown on a simple structure with the final conclusions about results of the analysis.

In recent decades, the use of built-up cold-formed steel sections in composite steel-concrete structures has become increasingly popular due to their advantages. These systems are easy to manipulate, transport and erect because of their reduced weight. These advantages are even more significant when the system is designed to be demountable, reflecting the environmental impact at the end of the system’s life. This paper aims to discuss a cold-formed steel-concrete composite floor system as part of the LWT-FLOOR project at the Faculty of Civil Engineering, University of Zagreb, Croatia. The built-up beams in this system consist of back-to-back “C” profiles as flanges and corrugated webs, which are connected using fast and productive spot-welding technology. Innovative demountable shear connections with structural bolts enable composite action between steel and concrete. The LWT-FLOOR system has numerous potential benefits, which will be investigated through experimental and numerical research supported by probabilistic methods and life cycle analyses. This paper presents the overview of project objectives, emphasising conducted and planned experimental research, which will be base for further project activities.

This article focuses on the analysis of axially compressed thin-walled built-up closed cross-section columns. The built-up nature of the cross-section is carefully considered in the calculation procedures and optimization constraints, accounting for the connection of profiles through the flanges within the cross-section. The calculation procedures are based on Eurocode 3 [1], which encompasses local, distortional, and global buckling forms. Five types of closed column cross-sections, ranging in height from 2 to 4 m, and subjected to axial loads of 50, 100, 200, and 500 kN, were thoroughly analyzed and optimized. The first type of cross-section examined was a square cross-section without stiffeners, while the remaining types featured four web stiffeners with varying geometrical constraints. The constrained nonlinear optimization solver, fmincon in Matlab software, was selected for the optimization problem. The obtained optimal cross-section results indicate that the square cross-section consistently exhibited the lowest effectiveness across all column heights and axial load combinations. In contrast, the most effective cross-section type transformed to a form, similar to a circle. Moreover, cross-section types with deeper stiffeners were associated with thinner profile thickness. A comprehensive summary of the results demonstrates that the effective area ratio within the cross-section was higher for smaller column heights and larger axial loads across all cross-section types. In conclusion, this study provides valuable insights into the analysis and optimization of axially compressed thin-walled built-up closed cross-section columns. The findings underscore the superiority of cross-sections that adopt a circular form and feature deeper stiffeners, resulting in enhanced structural effectiveness.

The present research investigates the utilization of polypropylene macro fibres, specifically Durus EasyFinish fibers developed by Adfil, for the purpose of mitigating plastic shrinkage cracking and drying shrinkage cracking in structural concrete. The incorporation of synthetic macro-fibres is analysed to ascertain their advantages in preventing plastic shrinkage cracking, a phenomenon that arises when the surface of freshly poured concrete undergoes rapid drying. The study focuses on evaluating the performance of concrete beams during the early stages, with a comprehensive assessment of their strength at various time intervals. The residual flexural strength is evaluated by conducting 3-point bending tests following the EN14651 standard. To assess the efficacy of synthetic macro-fibres, testing methodologies such as plastic shrinkage testing and restraint concrete testing are employed. The obtained results indicate a noteworthy reduction in shrinkage cracks with an increase in fibre dosage, thereby indicating improved physical properties of concrete during the initial stages. Moreover, in order to optimize performance, attention is given to the curing processes and concrete mix design. A shrinkage-reducing agent is introduced as an additional measure to minimize shrinkage potential and subsequently decrease the likelihood of crack formation. Overall, this research conclusively establishes the effectiveness of synthetic macro-fibres in mitigating concrete shrinkage cracking.

Although the significance of the interaction between concrete and reinforcement for reinforced concrete mechanics is well-known, its inherent complexity necessitates in-depth microscopy research. In this study, contact zones between concrete and reinforcement were examined using a short RC tie under tension that was shorter than the mean crack spacing for that tie. The specimen cross-section was 150 × 150 mm and it was centrically reinforced with a D16 single ribbed bar. A three-dimensional finite element approach with a slightly changed rebar shape is used for rib-scale simulation. At first, a sensitivity study was conducted on the contact zone parameters including initial cohesion, tensile stiffness, and angle of internal friction. Later, new values for normal and tangential stiffness were introduced that best fitted the experimental data at 40 kN load for a particular diameter of rebar. These values were used to inspect steel strain profiles at different load levels and compare them with experimental evidence.

Dapped-end beams, prevalent in structural design for their distinct advantages, pose unique challenges when integrating prestressed reinforcement. The geometric discontinuities in these beams result in complex stress patterns that are not accurately accounted for by conventional design calculations. Moreover, the effect of prestressing on these beams’ bearing capacity, particularly in specific configurations, is not thoroughly understood. This research uses a numerical parametric analysis to scrutinize the influence of prestressed strand placement in the dapped end and the intensity of prestressing. The severity of the decrease in bearing capacity was found to be dependent on the distance of the prestressing strands from the bottom face of the beam, with larger distances resulting in a less severe impact. In cases of beams without longitudinal and shear reinforcement, the effect was notably substantial, leading to reductions ranging from a significant 40.1% to a minimal 2.2%. For fully reinforced beams, the influence of the strand distance was less pronounced, leading to reductions between 22.9% and 18.8%. The study revealed a direct correlation between the intensity of the prestressing force and the reduction in bearing capacity. In every instance examined, an escalation in prestressing intensity corresponded to a more noticeable decrease in bearing capacity. For reinforced beams, a decrease of up to 22.9% was observed when the σcp/fcm ratio approximated 0.25. The research emphasizes the importance of considering this impact during the design process of such beams.

Increasing population results in significant concrete demand for housing and infrastructure. On the other hand, concrete has several potential environmental impacts including global warming due to CO2 emissions and energy demand and water scarcity due to water consumption for its production. Therefore, it is crucial to assess environmental concerns in concrete production for sustainable construction. Low emissions advanced performance (LEAP) concrete uses fillers – fine particulates that are inert when mixed with water and cement – as binder replacement to reduce CO2 emissions and energy consumption. The dilution of binder by a high amount of filler can be compensated by reducing the volume of mixing water needed to achieve concrete desired rheological behavior through packing techniques combined with chemical admixtures -superplasticizers- for adequate particle dispersion. This technology achieves the required compressive strength and rheology while reducing cement’s CO2 emissions. This study estimates and compares the water to produce LEAP and conventional concrete in order to complement their environmental profile. Water for aggregates and cement production is considered in addition to mixing water. The results are estimated in ranges to include variations due to technological routes. Primary data are used for the LEAP and conventional concrete formulations and data from the industry are used for the water activities other than concrete mixing. The results show LEAP concrete to have slightly lower water consumption than conventional concrete which together with low CO2 emissions suggests that this is a potential solution for sustainable construction, however, further analysis is needed.

Experimental tests of bending reinforced concrete slab have shown that flexural strength of reinforced concrete voided slab with hollow plastic inserts is lower than flexural strength of continuous cross section slabs (solid slab). Investigation of experimental data from science publications illustrates that difference of strength between voided slab with plastic hollow inserts and similar solid slabs can vary, from 3% to 27%. During the experiments was evaluated, that variation of flexural strength depends on lots of factors as: plastic void's shape form, installed quantity of plastic elements in the slab, distance between plastic voids, ratio of plastic hollow void’s diameter with the slab's height. Meanwhile flexural strength evaluation methods, as EC2 do not take in account of influence of plastic voided hollow inserts in the calculation of flexural strength. Therefore, was made analytical calculations according to experimental bending tests of voided reinforced concrete slabs with plastic hollow inserts to find and propose corrections for evaluation of flexural strength of reinforced concrete voided slabs with plastic hollow inserts.

The discrete cracks approach is proposed for deformational analysis of reinforced concrete members as an alternative method of the classical smeared crack techniques. It evaluates analytically the effects of concrete shrinkage, developed in a period before loading, and bond at the contact interface of reinforcing bars and surrounding concrete. Consequently, the history of evolution of the major, discrete cracks patterns is considered at a monotonically increased loading. The cracking process is analyzed by superposing the symmetrical and asymmetrical bond problems during it. The asymmetrical problem is resolved by introducing the increments of forces and bending moments due to appearance of major cracks. The proposed approach is applied for prediction of the stress-strain state and deflections of the beams with different ratios of reinforcement. The mid-span deflections, calculated using the discrete cracks model, agree sufficiently well with those obtained by the Eurocode-2 technique based on the smeared crack approach. The tension stiffening effect is clearly indicated for the beam with a small reinforcement ratio.

The temperatures in cities increase annually. This may be because of the development of cities with an increase in the number of buildings. A thermal storage building exterior that uses phase change materials (PCMs) to mitigate the heat island phenomenon was developed. As the temperatures of exterior walls increase because of solar radiation, the temperatures of cities tend to increase. Paraffin as PCM with melting points of 36 ℃ and 44℃ were used in this study. Three types of PCM specimens (paraffin-based microcapsules and board and gel types) were prepared, and their thermal and strength properties were evaluated. Regarding the thermal properties, the PCM successfully reduced the heat increase in the specimen. The gel-type specimen exhibited a better heat storage effect, and the temperature-controlling performance was accompanied by a substantial increase in PCM content. For the strength properties, the compressive and bending strengths decreased with increasing PCM content. A mortar specimen with 20% microcapsule content was found to be the most suitable mixture in terms of heat reduction and strength.

The Kevlar fabric composites have a wide range of applications in the body armor and lightweight vehicle-armor structures. Nanoparticles are one of the most common nanofillers for these structures. In this research, the testing specimens have been made from the Kevlar fabrics impregnated with the poly (vinyl butyral)/ethanol solution which had been reinforced with the ZnO nanoparticles. The two-layered composite samples have been fabricated by means of hot compression. The immersion of the square Kevlar/PVB specimens for the water uptake measurements has been performed according to the ISO 62 standard. The specimens have been immersed in a water bath filled with the distilled water (40 ℃) in the period of 8 weeks. The Kevlar/PVB specimens have been tested in accordance with the ASTM D 3039 standard for the tensile properties and the ASTM D 790–03 standard for the flexural properties. The tensile and bending characteristics of the dry specimens have been compared with the ones that had undergone the water immersion.

In this article, the impact of industrial waste pozzolanic additives (spent fluidized bed cracking catalyst waste FCCW and metakaolin from the production of expanded glass granules MW) on the structure and properties of expanded glass granules (EG) cement-based composite (density, compressive strength at 7 and 28 days and shrinkage) was analysed. The surface of the EG was determined to be porous and coated with metakaolin, resulting in the formation of additional hydration products around the EG during the curing of the lightweight cement-based composite. This layer of metakaolin and the open porosity of EG improve the bonding of the granules to the cement matrix of the composite. The analysis of mechanical properties of the lightweight composite showed that the combined pozzolanic additive (FCCW + MW) had the highest compressive strength at 28 days and the lowest drying shrinkage, compared to control samples without industrial waste pozzolanic additives and if they are used separately.

Sunflower plants grow in abundance in southwestern France. In addition to their wide availability, the sunflower pith particles stand out thanks to their alveolar structure and their particle porosity. Indeed, sunflower pith particles differ from other agricultural by-products by their honeycomb structure and their high porosity which gives them a high insulating potential. The use of these kinds of biobased materials is increasing due to their good environmental performances. The purpose of this project is to investigate the possibility of mixing pith particles with a biobased glue in order to manufacture cold pressed panels. The thermal insulation properties of these materials, as well as their mechanical properties through bending and compression tests and the impact of natural and accelerated ageing on the latter are studied. The present paper focuses on the properties of the panels at the initial stage. Two different biobased binders with various content were used to prepare the sunflower pith panels with densities ranging from 34 to 48 kg/m $$^3$$ 3 . The first binder was a commercial starch-based glue, the second one was pea starch. The results show very good thermal conductivities (from 0.040 to 0.043 W/(m.K)) and average mechanical values for these types of lightweight materials.

There is great potential for 3D concrete printing to revolutionize the construction industry in the near future. A major aspect of this technology transfer to the practical application will be the ability to control and mitigate the shrinkage of printed elements and shrinkage-related cracking. In the first hours after extrusion, 3D-printed concrete elements are subjected to the accelerated evaporation of the water. This leads to the development of high negative capillary pressure in the system. Before solidification, primary negative capillary pressure is responsible for the volumetric contractions of the 3D-printed concrete elements and subsequently cracking. Over time, printed structures with cracks degrade their durability, functionality, and aesthetics. Mitigating plastic shrinkage and shrinkage cracking is essential for 3D-printing sustainable and durable structures. The article analyses the cracking of the 3D-printed elements having different cross-sections of the layers. It was found that concrete elements printed with thin filaments are more susceptible to plastic shrinkage cracking than those printed with thicker filaments.

This research aims to produce artificial aggregates of the fine fraction of construction demolition waste (CDW). Before the investigations, the fine fraction of CDW (< 4 mm) is sorted in concrete and brick demolition waste and ground and sieved to comparable fineness. Two methods were chosen and compared for the production of artificial aggregates. For the first method, a sodium silicate solution was chosen as a binder to activate the starting material for producing alkali-activated aggregates (AAA) without a core structure. For the second method, different amounts of cement and water were mixed with the starting material to produce cement-activated aggregates (CAA) with a core-shell structure. In both methods, the aggregates were produced using a pelletizer. The performance of the aggregates was evaluated in terms of bulk crushing resistance, particle and loose bulk density, and water absorption. The results indicate that AAA and CAA reach properties in the range of lightweight aggregates. CAA achieves about 25% higher bulk crushing resistance than AAA. Cement content highly affects bulk crushing resistance and densities.

Refractory bricks are used worldwide in thermal setups such as coke ovens, blast furnaces and power plants because they can work at high process temperatures. Undesirable processes of erosion, wear, crack formation and failure of the refractory materials take place particularly upon the thermal setups operation, in which the working surfaces of ovens are subjected to strong thermo-mechanical stresses. Prolonging the life of refractory elements will give a significant economic effect for every production process. This can be achieved by a modification of surfaces of refractory materials by means of cold spray process.In the cold spraying method, fine solid particles are dispersed in a gas stream, accelerated by a Laval nozzle to supersonic velocities (500–1200 m/s) and deposited on the substrate surface by impact forming a strong bonding. In this work, bonding mechanisms of the fine particles cold sprayed on the porous surface of refractory materials and the formation mechanisms of the protection layer are studied experimentally and by numerical simulations.The surface properties, such as the porosity, roughness, hardness are analyzed using SEM, confocal microscopy and nanoindentation, respectively. The bonding strength of deposited particles is characterized with ultrasonic tests.

Materials, as both structure and expression elements, have always been affecting architectural design. However, over the years, the use of advanced technology has provided a wide range of possibilities in implementing architectural design. In the latter part of the 20th century, especially in Nanotechnology, scientific and technological advancements encouraged new approaches for architecture. Meanwhile, Nanotechnology, as a new innovative technology field, provides new, and revolutionary materials that can drastically affect design and performance of buildings. In the present study, the advantages of nanotechnology materials in building construction, which give new properties to structural forms and their load-bearing capacity, making them “smart buildings”, are explored. Also, this research tends to build a knowledge framework that includes nanomaterials, their types and characteristics providing means and ways responding to any kind of mission and realization of ideas and forms, in the field of architectural creation. In addition, the aim of this paper, is to introduce the use of nanotechnology materials in architecture, which can satisfy the requirements of today’s building users, including the life cycle of the building, its overall cost, energy independence and efficiency, as well as its sustainability. The combination of innovative capabilities is presented through examples of Nanotechnology materials real application in the construction field, such as the flexibility and dynamics of forms and aesthetics, the protection of the quality of living conditions and the control of microclimate, functions that are now feasible.

In this study, a concrete was prepared using glass processing waste, which replaced a certain amount of cement. These experiments were conducted to determine how the amount of glass processing waste affects the properties of fresh and hardened concrete. The experiments used cement, sand, dolomite, chemical admixtures, water and glass processing waste. In the experiments the amount of cement was replaced with glass processing waste from 5% to 30%. For the fresh concrete mixture, density and air content were determined. For the hardened concrete density, compressive strength, flexural strength, and water absorption, were determined. From the tests, it was determined that when up to 20% of the cement was replaced with glass processing waste, the properties of the concrete improved. Based on all the results obtained from the study, it was concluded that the optimal amount of cement that can be replaced with glass processing waste is up to 20%.

The main goal of this article is to study various ways of utilization of secondary raw materials in combination with superabsorbent polymers (SAPs) and observe the influence of combinations of these materials on the final properties of building materials. This combination of raw materials has not yet been examined and it is possible, that the presence of SAPs might increase the possible utilization of secondary raw materials in the building industry. The secondary raw material chosen to be tested in this research is a by-product of the energy industry, concretely high-temperature fly ash. After designing various compositions of cement pastes representing combinations of two types of SAPs with various properties with fly ash and cement their physico-mechanical and mineralogical properties were determined. Conclusions on the utilization of internal curing of superabsorbent polymers on the incorporation of secondary raw material were decided in the early stages of hydration were determined. The superabsorbent polymer can be used for the purposes of internal curing of the cement-based mixture in the early stages of hydration. The addition of fly ash has a very positive impact on the decreasing of compressive strengths caused by the addition of SAP.

This research investigates the impact of a modified biopolymer, retrograded corn starch, on the physical-mechanical and hygroscopic properties of clay composites. Clay composites were produced using varying amounts of the modified biopolymer (2.5%, 5%, 7.5%, 10%). Results showed that the addition of the retrograded starch polymer had a significant effect on the properties of the clay composites. Incorporating of retrograded starch polymer into the clay matrix resulted in a 72% increase in compressive strength (6.8 to 11.9 MPa), a 29% increase in surface moisture adsorption (from 141.1 to 182.43 g/m2), and a 36% decrease in the initial rate of capillarity absorption (from 0.55 to 0.35 g/cm2*min).

Metakaolin (MK), which is of higher fineness than cement, is an emerging supplementary cementitious material for the production of high performance concrete. Silica fume (SF), which is of even higher fineness, has been used widely for the production of high strength concrete or ultra-high strength concrete. Very often, either MK or SF is being added to the concrete mix alone. Theoretically, they can also be added together but there are relatively few trials. In this study, the possible synergistic effect of MK and SF on strength of mortar phase of concrete was evaluated. For this purpose, mortar mixes containing varying MK and SF contents at four different water/cementitious materials (W/CM) ratios were prepared and tested. Experimental results show that both MK and SF can improve strength; moreover, the co-addition of MK and SF has synergistic effect in increasing strength over the sole addition of MK or SF at the same cement replacement ratio.

The use of alternative waters rather than freshwater for concrete production is thought to be inevitable in the near future due to water scarcity. One of the alternatives is seawater. While the interest in the topic has increased dramatically and hundreds of papers have been published recently, the reported results in the literature were conflicted. It was attributed to different ion concentrations of seawaters. Moreover, the research on the fresh state properties of seawater cementitious materials has been limited. In that study, the roles of the types of mix water, different ion concentrations, and metakaolin substitution on the fresh state properties of cementitious materials were investigated. The results showed that while the use of seawater slightly decreased flowability, ion concentration did not show a significant effect on it. Freshwater samples showed lower shear stresses than all seawater samples at the same shear strains. Higher ion concentration resulted in increased viscosity. On the other hand, metakaolin substitution was more dominant on the fresh state properties rather than the type of mix water and ion concentration.

This paper presents a comparison of mechanical and chemical prestressing of fibre reinforced polymer (FRP) rods. Prestressing can be a solution to improve serviceability performance of FRP. However, current research is mainly focused on costly carbon fibre reinforcement rod (CFRP) chemical prestressing, whereas glass fibre reinforcement rod (GFRP) with established durability tests and proven serviceability limit for 100 years could be a potential economical option. Split wedge anchors for mechanical prestressing prevents notching of the FRP tendon and proved to be more effective. Chemical prestressing was investigated as a preferred option whereas anchors for FRP still require further development. In this case, expansion in concrete with special additives helps to generate tension in concrete reinforcement and prestress steel or FRP rebar. Expansive high-performance concrete (HPC) during chemical prestressing can provide similar expansion as mechanical anchors. Tensile properties of expansive mortar can be highly influenced by restraint. Higher cracking strain capacity, non-linearity and substantial plastic deformation can be achieved. The restrained expansive concrete undergoes much larger plastic deformation before cracking as well as residual deformation after failure because of bonding with rebar. Chemical prestress results of internal steel and CFRP can help to define a method of prestressing GFRP. Literature review proved that chemical prestressing with CFRP achieved 70% self-prestress. This development creates possibilities for more common GFRP rods and non-corrosive pretensioned reinforcement, avoiding complex pretension methods.

Pervious concrete (PC) is an environmentally-friendly material that exhibits properties such as permeability, water retention, and the ability to serve as a base for vegetation. The purpose of this study is to develop an affordable, straightforward, and rapid measurement technique utilizing mobile devices, such as personal computers (Mac and Windows) and smartphones (Android and iPhone), to evaluate PC’s dynamic elastic modulus. In this study, measurements of the dynamic elastic modulus were conducted on PC specimens with different porosities using these devices. The influence of using these devices with or without external microphones was also examined. The results confirmed that as porosity increased, the dynamic elastic modulus of PC decreased, with the relationship between them exhibiting a linear function. The dynamic elastic moduli were predominantly unaffected by the type of device used or the presence of external microphones. Measurements using mobile devices also showed a very high accuracy, with the standard deviation data and the coefficient of variance being under 0.4 and 4% respectively, for all specimens.

The use of high-frequency electromagnetic microwave radiation in civil engineering is no novelty. There have been various discussions related to this issue. However, they are often based on inaccurate and superficial knowledge. One of the reasons is insufficient access to accurate data with professional description for readers. Since it is a very effective method, it is necessary to realize that every company protects their know-how. Therefore, the aim is to introduce the methods and effectiveness of this microwave (EMW) technology in civil engineering practice. As it is a very effective technology, BUT Brno (Faculty of Civil Engineering) cooperated with a commercial company and performed numerous measurements and experiments that were often close to the conditions occurring at real constructions. Furthermore, BUT Brno, together with the commercial company, performed a large number of measurements in situ conditions related to the sterilization of biotic agents by means of microwave technology. In most cases the measurements were performed at real constructions and focused on drying, moisture elimination, and inactivation of biotic pests.

Problems related to the harmfulness and disposal of asbestos materials are well known all over the world. The paper presents the results of research on asbestos waste thermal treatment that is focused on the obtaining of mineral binders. The tests were performed in an electric arc-resistance furnace, in two different ways. The test results have demonstrated that the fibrous structure of asbestos contained in cement-asbestos waste is completely destroyed by thermal treatment, which allows the conversion of asbestos-containing materials into new secondary raw materials without asbestos. Moreover, the so obtained new materials exhibit binding properties close to those of traditional mineral binders, like ordinary Portland cement clinker. The research results indicate that the asbestos waste treatment process is a potential and interesting method of neutralizing this hazardous asbestos waste, enabling the material to be further recycled in the future.

Energy-efficient production with the use of waste materials is the focus of the research. A modern economy requires the production of materials to consider sustainable criteria. Therefore, the research limits the use of different materials to waste glass and soot as appropriate parts of a sustainable composition. There are several possible applications of glass-clay products in the construction industry-lightweight partitions and insulation materials. The most challenging part of creating a composition is to make a composition with predefined properties. The most significant are compression strength, volume weight, and porosity for the intended application. The research aims to analyze the influence of boric acid on a composition using boric acid as an additive. Volume weight was defined, and a compression strength test was performed to identify the most significant properties of the glass-clay composition. The results were analyzed, and a conclusion about using boric acid in the composition was formulated.

This paper discusses the structure and properties of high-performance concrete (HPC) analysed by scanning electron microscopy, X-ray diffraction analysis, exothermic temperature, density, bending, and compressive strength. A certain amount of cement (5%, 10%, 20%) was replaced in the concrete mixes with metakaolin waste generated in the expanded glass manufacturing. This metakaolin waste consists of a high amount of SiO2 + Al2O3 – 92.2% and has significant pozzolanic activity according to the Chapelle test – 1148mg/g. The results presented in the paper show that metakaolin waste is an active additive that accelerates the setting of HPC and makes its structure denser. HPC with up to 10% of cement CEM I 52,5 R substituted with metakaolin has approximately 28 day flexural and compressive strengths similar to control samples – 15 MPa and 135 MPa, respectively. The article also presents test results showing that metakaolin waste reduces the maximum temperature of the exothermic reaction in concrete and does not cause the formation of new compounds. Standard concrete minerals: portlandite, calcite, quartz, and alite were identified.

The present work investigates medium cement content (MCC) refractory castable modified by graphene oxide (GO) having oxidation degree of ~ 4. For the evaluation of the effect of GO on the hydration and structure of the castable, XRD and SEM analyses were performed. The study also included heating-cooling cycles and mechanical tests. The addition of GO changes the hydration of calcium aluminate cement (CAC) and the structure of CAC stone: the maximum intensities corresponding to the more stable hydrates of C2AH8 were found to be higher and those of unstable CAH10, presumably lower, presumably, when the MCC samples are fired at 1000 ℃ temperature, a larger amount of anorthite mineral is formed, improving the mechanical properties of MCC. After curing and drying at 110 ℃, the addition of GO does not affect density and strength, but after the samples are treated at 1000 ℃, the strength of the MCC samples increases by ~ 9% compared to the control samples. The residual compressive strength after 30 heating-cooling cycles also increases ~30% compared to the control samples.

Biomass fly ash (BFA) and phosphogypsum (PG) are by-products of wood biomass combustion in thermal power plants and phosphoric acid production. PG is formed during the decomposition of phosphate raw materials by sulfuric and phosphoric acids. About 1.5 million tons of PG waste is generated in Lithuania each year, whereas the BFA waste amount will triple by 2035 compared with the 2008 levels. This paper investigated the effect of PG content on the rheological properties and physical-mechanical properties of pastes based on BFA and PG. Increasing the PG content from 0 to 100 wt% in the paste increases the highest exothermic temperature (from 29.5 to 47.4 ℃) and compressive strength (from 3.02 to 26.53 MPa after 28 days of curing). XRD analysis shows that increasing the PG content increases gypsum crystallization.

The incorporation of additive manufacturing into the architectural and structural engineering realms mainly focused on producing physical models of conventional designs that do not showcase the benefits of using this fabrication approach. Furthermore, the design of space frame structures is centered on simple geometric forms where the members are linked using standard joints with unrefined geometries, giving them their industrial aesthetic. Applying additive manufacturing to the design workflow has the potential to create custom joints with optimized structural performance and reduced fabrication lead times. This research explored the application potential of topology optimization in the design and fabrication of structural nodes for space frame structures using additive manufacturing. This paper presents a methodology that streamlines the various stages in the structural optimization of a typical node in a double layer grid space frame. Topology optimization using SIMP is employed to create a structural node with enhanced stress distribution compared to a conventional spherical node. An algorithm streamlining the various post-processing stages into a single Grasshopper script is also presented.

Aerated autoclaved concrete (AAC) is a building material consisting of lime, cement, siliceous components, and aerating agents. The samples are cured by hydrothermal conditions in order to achieve a solid structure by the tobermorite formation. This article is focused on the possibilities of alternative raw material utilizations by preparation of aerated autoclaved concrete and its influence on the workability of fresh mix, water consumption, and basic physical-mechanical properties of hardened samples. Basic raw materials such as lime, cement, sand, aluminium powder, gypsum, and FBC fly ash were used in the experiment. At 20% wt., recycled glass, coal slag, and two types of fibre-like glass were used as a substitution for sand. As a first step, properties in their fresh state were determined, mainly consistency and how it was influenced by water absorption of alternative raw materials. The results of the experiments showed that the fibre-like glass has up to twice the absorbency, and to achieve the necessary consistency it is necessary to increase the water/solid coefficient by twofold. Further, the properties in a hardened state, such as bulk density, compressive strength, and coefficient of constructive quality were determined. Fibre-like glass (FLG 2) is the optimal secondary raw material which, with its parameters, is closest to the results of those samples based on primary silica sand.

3D printed concrete is a special type of concrete that can be laid through a 3D printer layer by layer without any formwork support or vibration. Important performance indicators of this concrete: rheology, mechanical properties, durability, can be optimized by choosing various materials. The purpose of this work is to use a mineral additive - perlite - in 3D concrete. In the studies, the pearlite content was up to 11.5%. Rheological tests of modified cement mortars were carried out using a rotary rheometer Rheotest RN 4.1, determining flow curves, ultimate shear stresses and plastic viscosity after mixing and after 60 min. Volumetric coefficient of water separation was calculated, the density and compressive strength were determined. It can be stated that the pearlite additive improves the formability of concrete mixtures using 3D printing technology, reduces the density of concrete, which increases the stability of the concrete mixture and reduces the thermal conductivity of concrete during the exploatation of the product.

Cultural heritage is a characteristic feature of every country that tells about the past. A country seeking to preserve its history must respect, protect and restore cultural heritage objects: buildings, monuments, historical places and all things that are historically valuable. When it comes to buildings as cultural heritage objects, a problem is usually relevant: how to restore them without losing their authenticity. In order for valuable building structures not to lose value during their restoration, materiality, condition and rehabilitation technique are determined before work is carried out. This article deals with the problems of the reconstruction of brick structures of cultural heritage buildings. The authors analyze the technologies for strengthening and restoring brick walls. A decision support system (DSS) for evaluating alternative reconstruction technologies for damaged building structures is being established. The indicators for multi-criteria assessment of reconstruction technologies are determined, their importance calculated and the multi-criteria TOPSIS method selected and described. Damages to brick walls in a particular building are described and three alternative technologies are determined for their restoration. The assessment by the decision-support system shows that in a particular case the most rational technology is the “bricking up of missing wall fragments”. Developed DSS is a unique and useful tool that can be used by professionals selecting rehabilitation techniques for vulnerable building structures.

Unmanned Aerial Vehicles (UASs), also referred to as unpiloted aerial drones or vehicles, has currently attracted high attention in the architecture, engineering, and operations due to it great maneuverability. The aim of this study is to evaluate the use of Unmanned Arial System (Drone) on Risk/Accidents Involved in Construction Project Monitoring in Enugu State, Nigeria and also the potentials of applying UASs in capturing multi-sensory data in construction project. Estimate, 60.000 fatal accidents occur annually worldwide in the construction industry and one worker loss his life every 10 min because of an occupational accident. Construction accidents are associated with different factors which has been studied by many scholars which formed the basis for data generated for this study. The target population in the study composes of of the Architects, Quantity Surveyors, Project Managers, Land Surveyors, Civil and Structural Engineers, Mechanical and Electrical Engineers and Builders in Enugu State, Nigeria as they are the primary participants who have substantial involvement and responsibilities in Project Monitoring. The study shows that drone technology if employment for construction project monitoring will reduce site accidents such as; accident on transit, falling debris, natural disaster, falls from high heights or scaffolding, exposure to dangerous chemicals or toxins and harmful materials on site.

Choosing the pricing of a construction project and the type of construction contract from the perspective of customers is a responsible and complex process. The success of a construction project depends on the correct decisions taken in the preparation of tender documents. This process is complex, and the most mistakes are made in this phase. Disputes between customers and contractors arise during the implementation of a contract, which can have a significant impact on the success of the project. There have been a number of studies on the choice of construction project costs from the point of view of contractors when submitting commercial bids. The main objective of this study is to propose a mathematical model from the point of view of customer, and an online tool for the pricing of a construction project and for the selection of the type of construction contract. The paper analyses scientific sources, presents the algorithm of the mathematical model, the application of the mathematical model in a real construction project, draws conclusions and makes recommendations on the appropriate pricing and type of construction contract.

A significant amount of the electricity needed to operate units of residential buildings can be generated from rooftop PV systems. This study developed system dynamics models to assess the impact of the overall satisfaction and subsidy policy with photovoltaic (PV) products for rooftops of residential buildings and households on energy security. The model was run by simulation from the year 2022 until 2035. Energy security was predicted. Results showed that at an overall satisfaction level and a subsidy proportion of 42% and 10%, the number of PV installations (generated PV power) in the year 2035 will reach 13.64 MW (9.01 GWh) and 26.99 GW (15.57 TWh), respectively. The cumulative subsidy cost reached 1.154 billion USD. In conclusion, manufacturers and suppliers of PV systems as well as the decision-makers in the energy sector can utilize the developed model as an assessment tool for improvement decisions to promote rooftop PV installations and secure sufficient renewable solar energy to meet the increasing annual energy demands.

The paper presents the real estate investment project evaluation system developed using multi-criteria decision-making methods and based on the findings of an empirical study analyzing the significance of sustainability criteria involving experts from the real estate and construction sector. The proposed evaluation system differs from conventional practices in that environmental, social and economic sustainability aspects are assessed as essential elements contributing to the financial value, taking into consideration the potential risks of long-term depreciation or opportunities for asset value increase. The hierarchical structure of evaluation criteria for real estate investment projects is presented, and the Economic Sustainability Index is derived, which is used to calculate the correction coefficient for financial value of investment projects. By incorporating the correction coefficient into the discounted cash flow analysis through an adjusted discount rate, a more accurate value for real estate investment projects can be determined. The practical application of the proposed multi-criteria evaluation system demonstrates its applicability to determine the financial efficiency of investment projects, with a particular focus on assessing the long-term value of real estate assets.

Construction uses different innovative solutions and advanced technologies to increase effectiveness, safety assessment, site preparation, logistic, save resources, reduce waste and reworks. One of the ways to find the best solution is introducing specific problem-based evaluation criteria and applying complex multi-criteria evaluation systems. The aim of the current research is to develop a multifaceted criteria system for evaluation of suspended veneer façade installation solutions by increasing effectiveness according to sustainability at the construction stage, including expert survey and determining relative significance (weights) of criteria. The authors suggested three groups of criteria, evaluating preparation for construction, installation and the result, each group consisting of eight criteria. Some criteria were analyzed together with the future application of decision system tools and building information modelling (BIM) for information management and data analysis. The determined criteria weights will be applied in ranking of alternative suspended veneer façade solutions by using multiple criteria decision-making methods.

In construction practice, all decisions are made in the context of imperfect information. The awareness of this means that efforts are made already during the preparation of decisions to limit the degree of risk and uncertainty resulting from such a nature of the available information. A risk assessment may prove particularly useful for this purpose. It can be carried out in a number of available ways. Such methods are usually based on the use of a specific methodology, expressing the complexity of the subject of the decision with the help of a specific – not sharp – representation of the available information and therefore requiring the use of advanced tools for its appropriate processing. However, it seems that there are also tools that provide appropriate, and at the same time much simpler, methods of risk assessment. Such tools undoubtedly include pairwise comparisons, in particular – the standard AHP/ANP method, using sharp data representation. In the context of risk assessment, a specific feature of this method is considered, consisting in the availability of various sharp rating scales. Their suitability for expressing different attitudes towards risk was assessed. Ultimately, it turned out that the conscious use of such scales enables the proper fulfillment of the needs related to risk assessment.

For all of the European Union countries, the European Green Deal has set ambitious objectives to become climate neutral by 2050. The global challenge is to achieve prosperity and sustainable economic development while reducing energy consumption and greenhouse gas emissions. All economic sectors must take action in order to achieve this goal. The construction industry has a large impact on fulfilling Green Deal objectives since it is one of the biggest consumers of finite natural resources and energy, as well as one of the biggest producers of carbon emissions and waste. The construction sector is under pressure to find and use alternative, sustainable, eco-friendly building materials, such as timber. However, despite the numerous benefits of timber, construction with timber is still not sufficiently developed in European countries. The aim of the research was to determine the main drivers and barriers to timber construction development across selected European countries. In addition, the education of the specialists, skill gaps, and required competencies were tackled. The research was based on a literature analysis and a questionnaire survey of the business companies. Analysis revealed that timber has numerous environmental, social, and economic benefits compared to traditional building materials such as steel or concrete. Major barriers to timber construction development are a lack of knowledge and skills, as well as concerns regarding fire safety and structural stability. A survey revealed that business companies lack skilled staff. To overcome this barrier, education in sustainable timber design and construction must be improved.

With the development of information technologies, they have been penetrating into a variety of construction activities, thus changing them. One such innovation that is changing the construction field is Decision Support Systems (DSS) that automate a decision-making process in various construction activities, making them more efficient. Therefore, it is important to know and understand the development of the DSS in the construction field to uncover emerging trends and explore the intellectual structure of the analysed field in the published papers. Consequently, this paper presents the results of the bibliometric analysis of papers from the Web of Science database and a keyword map of the DSS application in the construction field. Moreover, the countries collaboration map is presented in order to reveal the development of international cooperation in the DSS application in the construction field. The results obtained in this research will help scientists and practitioners to familiarize themselves with the found trends in the intellectual structure of the DSS application in the construction field, and to choose further directions for developing DSS in the construction field.

Building design is a broad and intensive collaborative process that involves a multitude of tasks and responsibilities that need to be accomplished in a timely and qualitative manner. The design process has a clearly expressed iterative nature - each solution is initially raised as a hypothesis, which is further discussed, analysed, calculated, checked, including compliance with normative requirements, and then final decisions are made after analysing several possible alternatives. This takes place in each team (discipline) of the project participants by comparing analysis results and anticipating the possible impact of decisions on the solutions and results of other design teams (disciplines). Therefore, it is very important to coordinate, synchronize, reconcile, and manage these decision making iterations in a collaborative environment. The Building Information Modelling (BIM) technology encourages the development of harmonized information production and management processes, creating preconditions for real collaboration between design partners in a unified model (the prototype of real building) environment and enables this model to be used for multivariate virtual testing. This feature is realized through the integration of modelling and analysis and computing systems, when the data transfer from one system to another system ensures the connection between the physical and the analysis model and the integrity of their data. The article deals with the integration levels and systemic directions of architectural and structural modelling and design computation programs. The problem of physical construction model creation and conversion into analysis model is defined and the stages of Computer-Aided Design/Competer-Aidet Engineering (CAD/CAE) integrated design process are discussed.

Everyday experience tell us and confirms that professional human activities may be endangered a lot with occupational risks. This is why occupational safety (OS) assessment measures are applied to identify real threads and possible measures to prepare to face them and provide necessary OS level for workers and work environments in general. The reliable assessment of actual safety level depends on adequate occupational risk evaluation. There are a lot of risk assessment tools available. Each of them has advantages and disadvantages. Thus, there is no ideal tool, even in the case of a concrete work case. OS problems and use to be multidimensional and complex. This is why they are usually dealt with in two possible ways. The first one pertains to the application of complex, not so easy to comprehend, rather dedicated approaches while the second one pertains to the application of approaches that are easy to use but that also seem to be too simple and thus too inadequate. On the other hand, occupational safety assessment is susceptible to be supported by dedicated non-flexible tools which may make general occupational safety assessment methodology incoherent and fragmented. This is why the application of a specific methodology of occupational safety assessment is suggested in the paper. The methodology is based on the application of a universal multidimensional decision making support tools. It is easy to comprehend, it facilitates making occupational safety assessment more coherent between diverse areas and it allows effective coping with both complex and easier safety assessment problems while covering intangibility of available information.

The use of geosynthetics has gained increasing attention in recent years due to their potential benefits in various engineering applications. Geosynthetics are used to improve soil structures such as base courses or retaining walls, mostly through reinforcement, filtration, separation, and sealing functions. This paper examines the environmental and economic benefits of using geosynthetics in road, earthworks, and foundation engineering. The paper discusses soil reinforcement of base courses, construction of retaining walls, and sealing layers.One of the main environmental benefits of using geosynthetics is the reduction in the use of natural or manufactured resources such as concrete. Traditional construction methods often require excavation and transportation of large quantities of soil, rock, and other materials. By contrast, geosynthetics can be used to enhance the properties of existing soils, minimizing the need for additional materials. This significantly reduces the carbon footprint and improves the sustainability of construction projects.Case studies are presented to illustrate the benefits of geosynthetics in practice. The paper concludes that geosynthetics can provide significant environmental and economic benefits in construction and should be widely considered in construction projects.

The use of ground improvement technology, specifically soil injection using polyurethane resin, has gained significant attention in the construction industry for foundation sediments. This technique offers various applications in infrastructure projects and provides advantages such as preventing settlement, improving load-bearing capacity, and sealing underground structures. Traditional methods for stabilizing weak soil conditions are often time-consuming, costly, and may not produce desirable results. Polyurethane resin injection presents an alternative that requires minimal excavation, penetrates fine cracks and voids, and enhances the mechanical properties and stability of the soil. However, challenges such as achieving uniform resin distribution and accurately estimating injection volume and pressure exist. Ongoing research focuses on optimizing injection parameters, studying long-term performance, and understanding resin-soil interactions. Overall, soil injection using polyurethane resin shows promise for ground improvement and foundation stabilization, and further research is necessary to refine the technique and establish design guidelines for different soil conditions. This article provides an overview of the technology, including its properties, applications, advantages, and limitations, and presents a case study to demonstrate its effectiveness. The information presented enables engineers and construction professionals to make informed decisions about implementing this innovative technique in their projects.

All the sediments discharged from the Quaternary glaciers differ in their granulometric and mineral composition. Tills, sands, and clays cover unevenly sized areas in various places. However, during engineering geological and geotechnical investigations, the most found types of till soil are sandy low plasticity clay (saClL), sandy low plasticity clay-silt (saClL-SiL), and clayey sand (clSa). The last two mentioned are intermediate till soils which are mostly assigned as Medininkai glacial deposits. The analyzed intermediate glacial till deposits are distributed in the eastern part of Lithuania, where the biggest and the most complex buildings are being designed. During the research, about 80 moraine samples from the entire territory of Lithuania were investigated. Several samples were analysed using an SEM microscope. From all the obtained data a database was created, where all the data was summarized and analysed in P.K Robertson's graphs with SBT (Ic) zones. After research, intermediate till soil is characterized by low natural moisture content and high natural density, and it practically always has low plasticity, so the porosity rate of these soils is relatively low. This soil is less compressible. Investigated soil during this study mainly takes the position into P.K Robertson's graphs zones 4 (Silt mixtures) and 5 (Sand mixtures) mixtures where the Ic zone is 2.60. After research with an SEM, it can be stated that clay mineral mixtures (illite-smectite) and not clay minerals predominate in the investigated soils’ clay fraction.

The current discussion related to energy demandness, sometimes generally referred to by the abbreviation Green Deal, basically comes from two directions – reducing energy in absolute values, or when it is necessary to use renewable energy sources to a greater extent and thus reduce the consumption of fossil fuels. Construction is generally associated with high energy consumption, which is most often reported in the range of 30–40% of total consumption. However, current attention is mainly focused on buildings under the designation Energy Efficient Buildings - EEB.The contribution is therefore focused on the area of civil engineering structures, which still remains in the background of attention and is devoted to both the reduction of total energy consumption and the possibilities of using renewable energy sources. However, the main difference in possible energy savings compared to buildings can be determined in the different stages of preparation, construction, and structures phase of utilization. In the case of EEB, it is mainly about the reduction of consumption during the phase of the building utilization, in the case of civil engineering structures, it is mainly about the first phases. The basic possibilities of achieving these goals are therefore the main focus of the contribution, when the possibilities are primarily directed to the geotechnical constructions of transport structures.

Between two banks of the River Main in Frankfurt, Germany, a new high-rise building is planned with a challenging structural concept. The geotechnical boundary conditions, such as the location of the building, nearby sensitive traffic and infrastructures and quay walls defines the complexity of the nature of the project. The quay walls are more than 100 years and should be kept unaffected during and after the construction phases. The high-rise building will have a height of about 75 m and will be founded on a Combined Pile-Raft Foundation (CPRF) in the tertiary, soft marl. For analysis of the stability and the serviceability of the heavily eccentric loaded foundation of the new high-rise building and the existing structures and for the investigation of the soil-structure interaction complex three-dimensional, non-linear numerical simulations have been carried out. The paper introduces into a very complex construction project in which the realistic consideration of the soil-structure interaction is very important for the serviceability of the foundation of the planned high-rise building as well as for the surrounding infrastructure.

Road embankments are critical elements of modern transportation infrastructure that provide support and stability to the roadway. However, embankments can be vulnerable to slope instability due to factors such as poor soil quality, excessive loads, frost, and steep slopes. To address these challenges, engineers have developed various methods to reinforce embankments, including the use of geogrids. In this study examined mechanical properties of soil-geogrid interaction using laboratory testing method such as triaxial compression. Also, geotechnical software, such as GEO5, to assess the stability and safety of the structures was used. Analysis revealed that the required thickness of an additional soil layer to achieve the same slope stability as that with geogrid reinforcement depends on the soil type and slope steepness. Specifically, the higher the apparent cohesion of the soil, the smaller the thickness of the additional layer, while steeper slopes require greater thickness of the additional layer of soil. We also found that an alternative soil layer with apparent cohesion as a composite material has potential in slope stability calculations, but requires further analysis.

In modern construction, piles are often used due to their environmental friendliness and their ability to withstand large loads. However, different calculation methods are used in their design, which is suitable for specific geotechnical conditions. One of the main methods of ensuring the load-bearing capacity of piles is the static test of piles. However, when interpreting the results and the load-settlement curve, the problem arises of how to choose a method for determining the ultimate bearing capacity. This article reviews six graphical methods, applied to nine different length and diameter CFA piles installed in different construction sites in Lithuania. After analyzing the results, it was found that the largest variation of ultimate bearing capacity values was observed using the Decourt, Chin-Kondner, and Brinch Hansen 80% methods, while the smallest was observed using the Corps of Engineers method. It was also noted that when different load settlement curves were present, the Decourt, Chin-Kondner, and Brinch Hansen 80% methods yielded several times higher ultimate bearing capacities than those obtained using other methods.

The most part of radioactive wastes in Lithuania has been produced by Ignalina nuclear power plant (INPP). Geological studies for the analysis of Lithuanian geological setting suitability to host the deep geological repository (DGR) had been started at the end of last century. The geological investigations are comprehensive, time consuming and need a high qualification of the experts involved. Potentially suitable geological formations had been selected according to the criteria used in the best international practice. The potentially suitable formations for the DGR construction in Lithuania are the rocks of crystalline basement, lower Cambrian clay, upper Permian anhydrite and lower Triassic clay. A special program has been developed in Lithuania for the purpose of implementing the European Council Directive 2011/70/Euratom of 19 July 2011, establishing the Community framework for the responsible and safe management of spent nuclear fuel and radioactive waste. According to the program the responsibility for DGR project was delivered to INPP in 2019. The geological investigations take a big part of the program and several tasks have been solved already. Sites for the further investigations were identified in 2020, criteria for site exclusion were determined in 2021 and potentially suitable sites were ranked according to the suitability criteria in 2022. However, there are only several results of geological formations material investigations. The lack of such investigations is caused by insufficient financial resources. The material of geological strata should be tested in the natural conditions and new deep boreholes are needed for this purpose.

Statement of the problem. It is important to consider the characteristics of the soil base when calculating models of multi-story frame buildings and determining the forces and deformations in their elements. The influence of the foundation is manifested in the redistribution of forces in load-bearing structures and significantly affects the numerical results of the calculation [1]. Today, the requirements for the level of safety of residential buildings have increased, which requires a more complete consideration of the factors that affect the safety of structures. Thus, this study is very relevant. The paper analyzes three variants of models of interaction between a multi-storey frame building and a soil foundation. A modal analysis was performed to evaluate the influence of the soil foundation on the frequencies and eigenvalues of free vibrations of the building. The modeling was performed using the finite element method and implemented in the SCAD software package. The aim of the study is to assess the influence of the soil foundation on the stress-strain state of a multi-story frame building and the eigenvalues and frequencies of its natural vibration forms.