Dina M. Abdelsattar, Mahmoud Owais, Mohamed F. M. Fahmy
et al.
Abstract The cement industry is a significant contributor to CO2 emissions worldwide, which demands new measures to reduce its environmental impacts. Therefore, finding solutions to reduce the CO2 emissions in cement production became necessary. Pozzolanic materials offer an optimum solution approach with both environmental and functional advantages. For the investigation of pozzolan effects on the concrete mixture, the modeling part becomes a challenging task. This study models and predicts the compressive strength of pozzolanic cement-based concrete using deep residual neural networks (DRNNs) and variance-based sensitivity analysis (VBSA). The designed DRNNs architecture uses shortcuts (i.e., residual connections) that bypass some layers in the deep network structure in order to alleviate the problem of training with high accuracy. The research also examines crucial aspects such as pozzolan type, substitution ratio, component proportions, and grinding processes, using data developed by the authors and from different pozzolanic concrete compositions from various studies. The proposed model showed a high accuracy of R 2 = 0.94 for testing data that outperformed traditional literature models, enabling the generation of a large sample of synthetic experimental data for further analysis. The VBSA improves knowledge by prioritizing the importance of input factors, resulting in a complete method for designing concrete mixes. The analysis revealed that silica fume and volcanic ash were the most effective pozzolans in enhancing compressive strength, followed by scoria and metakaolin, with optimal substitution ratios ranging from 10 to 15% for most natural pozzolans and up to 20–30% for metakaolin and pumicite. Hence, this newly presented analysis framework offers an optimizing tool for pozzolanic concrete mix design that could investigate several pozzolana types/proportions, their efficiency, and the structural performance of the final concrete mixture.
Systems of building construction. Including fireproof construction, concrete construction
Ahmed Hamoda, Aref A. Abadel, Abedulgader Baktheer
et al.
Abstract Precast concrete-filled steel tubular (CFST) circular columns assembled with connecting joints are commonly employed in building structures. However, there is a lack of research regarding the behavior of precast CFST columns that are connected with construction joints made of high-performance concrete (HPC), such as engineered cementitious composites (ECC) as well as high-strength fiber-reinforced concrete (HSFRC). This paper presents an experimental investigation of precast CFST circular columns subjected to axial loads, tubed with galvanized steel sheets (GSS) and connected with joints made of ECC, HSFRC and normal concrete (NC). Ten slender columns are tested until collapse. The primary studied parameters include the development length along with the connection concrete type. The experimental results reveal that an increase in the development length of the reinforcement, i.e., the length of the connecting concrete joint significantly enhances both the cracking and the load-bearing capacity of slender CFST precast columns that are connected with an intermediate concrete joint. Moreover, the combination of GSS tubes with ECC and HSFRC joints markedly enhances the ultimate load, demonstrating an impressive increase of 115% and 247%, respectively, over the precast NC control column. In addition, three-dimensional nonlinear finite element modeling is performed considering the initially existing imperfection within the precast CFST columns which is validated against the experimentally obtained data. These models are utilized to further investigate parameters, such as GSS thickness and longitudinal reinforcement ratio.
Systems of building construction. Including fireproof construction, concrete construction
Abstract The study focuses on the development of cementitious composites using 3D printing and plastic waste as a sustainable aggregate substitute. This study involves experimenting with various percentages of plastic waste as a partial substitute for ground granulated blast furnace slag (GGBFS) in a control mix. The study examines the anisotropy of the 3D printing process, comparing it with properties of mold-cast samples. In addition, it assesses the fire resistance and mechanical properties of samples at elevated temperatures (100 °C, 300 °C, and 600 °C). Key mechanical properties, including 28-day compressive stress and flexural strength, are determined through experimental testing using a standard compression test and three-point bending test. The study also considers the modulus of elasticity (MOE) in compressive tests to evaluate a sample’s ability to deform elastically and the flexural toughness index to assess energy absorption and crack resistance of flexural samples. Following the experimental testing, the study’s key findings suggest that significant mass loss occurred at 300 °C and above, with plastic samples demonstrating increased mass loss at 600 °C. At 600 °C, plastic degradation led to the formation of voids and cracks within samples due to heightened internal pressure. Anisotropy was evident in 3D-printed samples, with loads parallel to the layer direction resulting in greater compressive strength and MOE. Furthermore, layer direction parallel to the longitudinal axis of flexural samples yielded higher flexural strength and flexural toughness. Mold-cast samples displayed superior compressive strength and stiffer behavior, with higher MOE compared to 3D-printed samples. However, 3D-printed plastic samples exhibited superior flexural strength compared to mold-cast samples, attributed to the alignment of plastic within the samples. The study also observed a reduction in compressive strength with the addition of plastic, explained by the poor bonding of plastic with cement due to its hydrophobic nature. Despite this, flexural strength generally improved with plastic addition, except at 600 °C, where plastic samples showed significant degradation in both compressive and flexural strength due to plastic degradation within the samples.
Systems of building construction. Including fireproof construction, concrete construction
Abstract In order to promote the engineering application of recycled concrete, the effects of PPF and nano-TiO2 dioxide on the mechanical properties and durability of recycled concrete were studied. Polypropylene fiber recycled concrete(PRAC) and nano-TiO2 recycled concrete(TRAC) were prepared by adding different volume contents of PPF and nano-TiO2. The experimental findings demonstrated that the PPF and nano-TiO2 improved the splitting tensile strength of RAC better than the compressive strength. When the volume content of nano-TiO2. and PPF is 0.8% and 1.0%, respectively, the corresponding splitting tensile strength of concrete reaches the maximum value(3.4 and 3.7 MPa). The contribution rates of nano-TiO2 and PPF with different volume contents to the mechanical properties of RAC have optimal values, which are 0.4 and 1.0%, respectively. The incorporation of nano-TiO2 and PPF can effectively inhibit the loss of RAC mass and the generation of pores under freeze–thaw conditions, and slow down the decrease of dynamic elastic modulus. When the volume content of PPF is 1.0% and the volume content of nano-TiO2 is 0.4%, the protection effect on the internal structure of RAC is better, and its carbon resistance is better. The results of RSM model analysis and prediction show that both PPF and nano-TiO2 can be used as admixture materials to improve the mechanical properties and durability of RAC, and the comprehensive improvement effect of PPF on RAC performance is better than that of nano-TiO2.
Systems of building construction. Including fireproof construction, concrete construction
Alexey A. Novikov, Lilia V. Shcherbatykh, Tatyana S. Zuban
et al.
The article presents an analysis of the current indicators of monitoring the socio-economic and legal status of employees of the federal fire service in accordance with the provisions of Federal Law 141-FZ dated 23 May 2016 and the Decree of the Government of the Russian Federation No 1548 dated 22 September 2023. There were reviewed both federal and territorial levels of the system of monitoring indicators. The problems related to implementation of sociological research at the local level were identified, and there was recommended to improve the monitoring system. The dependencies between indicators as well as their impact on the effectiveness of social support for employees were also discussed. There was substantiated the need for standardization and centralized data collection for more accurate analysis and administrative decision-making.
Systems of building construction. Including fireproof construction, concrete construction
Sergey M. Dymov, Maxim V. Vishchekin, Galina P. Surina
et al.
The article considers a computer program created to help employees of EMERCOM of Russia, designers, persons responsible for ensuring safety at facilities, as well as ordinary citizens who decided to choose and install means of rescue from a height. The choice is made according to one of the key parameters, namely, the cost.
Systems of building construction. Including fireproof construction, concrete construction
Shamsad Ahmad, Ashraf A. Bahraq, Amin Al-Fakih
et al.
Abstract The presence of low-quality coarse aggregates and exposure to aggressive conditions are the two major problems with the durability of concrete. Therefore, an alternative concrete with enhanced properties to prevent fluid and ionic mobility compared to conventional concrete is needed. This study investigated the effects of main mix parameters on the transport characteristics and corrosion behavior of ultra-high performance fiber-reinforced concrete (UHPFRC). A set of 27 UHPFRC mixtures with different combinations of w/b ratio, cement, and silica fume contents, based on a 33-factorial experiment design, were prepared and tested for water permeability, chloride penetrability, electrical resistivity, chloride profile, and corrosion current density. The results showed that UHPFRC mixtures exhibited excellent durability properties characterized by negligible water penetration (< 15 mm), negligible and very low chloride permeability when the w/b ratio was 0.15 (< 100 Coulombs) and up to 0.2 (< 300 Coulombs), respectively, and very low chloride concentrations at the rebar level (0.03–0.18 wt.%). All resistivity values were within the range of 26.7–78.8 kΩ cm (> 20 kΩ cm) and pH values were 12.41–13.01, indicating the implausible likelihood of corrosion in the UHPFRC mixtures. This was confirmed through the corrosion current density measurements of reinforced UHPFRC specimens after 450 days of chloride exposure, which were below the critical limit for the corrosion initiation of reinforcing steel. Finally, the experimental data were statistically analyzed and fitted for all the listed tests, and models were developed for them using the regression analysis such that regression coefficients were within 0.90–0.99.
Systems of building construction. Including fireproof construction, concrete construction
Abstract This study investigated the efficiency of CO2 curing in blast-furnace slag pastes activated with three concentrations of KOH solution (3, 4, and 5 M). The CO2 curing was applied into the alkali-activated slag paste for 3 days. The CO2-cured pastes were subjected to subsequent curing in a water bath or exposed to seawater. The mechanical properties and characteristics of the reaction products were compared. Full strength can be obtained within 3 days of the early CO2 curing. The strength remained almost constant regardless of the activator concentration. The CO2-cured samples produced more CaCO3 after exposure to the seawater. The carbonates filled the micropores of the samples, and no strength reduction was observed. The hydrates Ca(OH)2 and C–S–H(I) are carbonated, forming calcite and amorphous CaCO3 during the subsequent curing and exposure to seawater as well as the CO2 curing. A less dense matrix with a lower activator concentration facilitated the diffusion of CO2 and promoted early carbonation in the paste. The polymerization of C–S–H(I) was relatively slow with low activity, and within the period of CO2 curing, more carbonates were produced in the sample prepared at a low activator concentration.
Systems of building construction. Including fireproof construction, concrete construction
Abstract Self-compacting concrete (SCC), which flows under its own weight without being compacted or vibrating, requires no outside mechanical force to move. But like normal concrete, SCC has a brittle character (weak in tension) that causes sudden collapse with no advance notification. The tensile capacity of SCC has increased owing to the addition of steel fiber (SF). Various research concentrates on increasing the tensile strength (TS) of SCC by incorporating SF. To collect information on past research, present research developments, and future research directions on SF-reinforced SCC, however, a detailed review of the study is necessary. The main aspects of this review are the general introduction of SCC, fresh properties namely slump flow, slump T50, L box, and V funnel, and strength properties such as compressive, tensile, flexure, and elastic modulus. Furthermore, failure modes of steel fiber-reinforced SCC are also reviewed. Results suggest that the SF decreased the filling and passing ability. Furthermore, improvement in strength properties was also observed. However, some studies reported that SF had no effect or even decreased compressive capacity. Additionally, SF improved the tensile capacity of SCC and avoid undesirable brittle failure. Finally, the review recommends the substitution of secondary cementitious materials in SF-reinforced SCC to improve its compressive capacity.
Systems of building construction. Including fireproof construction, concrete construction
Riyadh Alsultani, Ibtisam R. Karim, Saleh I. Khassaf
Abstract The goal of the experiment described in this paper was to examine the effects of structure orientation (0°–90°) and fluid–structure interaction (FSI) under combined water loads, represented by water current and waves, and earthquake actions, on the dynamic response of a reduced-scale bridge pier specimen with pile foundation. The peak relative displacement and peak acceleration of the specimen are measured using the first time innovative in Iraq, Reality Water–Structure–Earthquake Interaction Test (RWSEIT). The findings are given and analyzed concerning water depths, current speed, wave characteristics, earthquake amplitudes, and structural orientations. A numerical model of the examined specimen with three dimensions (3D) was constructed, and the findings were successfully confirmed using the data from the experiments. A pile foundation bridge pier's 3D structural response under orientations that cannot be tested in a lab was computed using the constructed numerical model. The complicated dynamically produced FSI effects on the response of coastal pile foundation bridges may be better understood according to the research's experimental and numerical findings.
Systems of building construction. Including fireproof construction, concrete construction
The decentralization and post-war recovery processes raise the issue of sustainable territorial development to a qualitatively new level, based on innovation and the search for appropriate resources. The study aims to analyse the features of building institutional and innovative projects within the new concept of territorial development resources based on the archetypal approach and develop practical recommendations for their implementation on the example of sub-ethnic groups of the Sumy region. The study based on world experience substantiates that the process of innovative development of territories should not focus solely on economic issues and technological change but should consider socio-cultural aspects that can be viewed as an essential component of the potential. Considering territorial archetypes when initiating changes and resolving issues of territorial development will allow the development of effective measures through the rational use of resource potential. It is determined that the question of considering socio-cultural historical and modern approaches to to studying settlements, cities, and landscapes (regional and local aspects), analysis of their formation, change and development in developing strategies. The importance of the regional component is illustrated by the experience of the EU, where local authorities are gaining more and more ground in finding the most practical and concrete opportunities for territories. It is determined that public administration undergoes significant changes under the influence of postmodernism, a new philosophy of building organizational structures, government, and management. It considers the uncertainty and ambiguity of new types of social systems and is seen as open to the future. The authors consider the application of postmodern theories to be fruitful in studying the impact of the socio-cultural environment on socio-economic processes and adaptation of innovations. This factor’s impact on economic entities’ behaviour has traditionally been regarded as exogenous. Given the use of postmodern methodology must be studied when trying to return people and actual processes to a place occupied by abstract variables and modelled dependencies. The influence of postmodernism at the territorial level is determined based on the evolution of innovation communities. This approach is consistent with the current EU regional policy, which aims to enhance regions’ development by improving competitiveness efficiency. It is proposed to consider the possibility of using institutional and innovative projects for sustainable development of territories, considering the archetypal resource component and the concept of innovation communities. Institutional and innovative projects are considered so-called «security-related products» of territorial development, which may include innovative projects and programs that involve a wide range of resources, including socio-cultural, focused on achieving sustainable development goals. It is substantiated that the use of tools for institutional and innovative projects should be considered in the context of the smart specialization of regions, making it possible to consider the socio-cultural component practically. Examples of the use of archetypes for the construction of innovation and institutional projects in the instance of two sub-ethnic groups of the Sumy region are considered. The main archetypes of goryuns and sevryuks are generalized, and paper provides the related institutional and innovation projects they will promote.
Abstract The flexural behavior of basalt fiber (BF)/polypropylene fiber (PF)-reinforced concrete (BPRC) was investigated. When the content of BF and PF is 0.1%, the addition of fibers increases the compressive strength of concrete. A BF content of 0.1% has the most obvious effect on improving the compressive strength, but a hybrid fiber content of 0.2% exhibits a negative effect on the compressive strength. The addition of BF and PF can increase the flexural strength and the expansion tortuosity of the fracture cracks, thus enhancing the ductility of concrete. The hybrid fibers with content of 0.1% are most beneficial to increase the flexural strength. However, the ductility of concrete and the tortuosity of fracture crack decrease with the matrix strength, and the improvement proportion of fibers on the flexural strength also decreases. When the BF and PF are mixed, compared to the case of single fiber added, there is no significant change in the damage of BF, whereas the damage of PF is more severe. The flexural toughness index FTδ effectively characterizes the change in the flexural toughness of BPRC. The hybrid fiber contents of 0.1% and 0.2% exhibit the most significant improving effect on FT-l/600 and FT-l/150, respectively. Considering the influence of fibers on the compressive strength, flexural strength and flexural toughness of concrete, a hybrid content of 0.1% is the optimal choice of fiber content. A prediction model for flexural strength of BPRC is proposed based on the composite material theory.
Systems of building construction. Including fireproof construction, concrete construction
Жуков, А. Д., Бессонов, И. В., Попов, И. И.
et al.
Постановка задачи. Малоэтажное строительство характеризуется сравнительно невысокой стоимостью и возможностью формирования эффективных изоляционных оболочек сооружений. В качестве несущих конструкций используются каркасные и массивные стены, возможно использование бетонного полотна. С учетом сложившихся реалий наиболее актуальным является ориентация систем на применение отечественных материалов, в том числе способных эффективно функционировать в жестких климатических условиях. Результаты. Установлено, что свойства пенополиэтилена и изделий на его основе позволяют рекомендовать этот материала как для систем фасадной и кровельной изоляции, так и для систем, контактирующих с грунтом. Установлено, что пенополиэтилен практически не изменяет свойств в условиях замерзания до -70 С и в интервале знакопеременных температур от -60 до +70 С. При длительном контакте с водой или водонасыщенным грунтом свойства материала также характеризуются стабильностью. Выводы. Использование рулонного вспененного полиэтилена является перспективным как с точки зрения свойств самого материала, так и ввиду возможности формирования бесшовных изоляционных оболочек. Формирование бесшовных изоляционных оболочек создает практически непроницаемые тепло-, паро- и водоизоляционные барьеры по периметру изолируемого объекта. Statement of the problem. Low-rise construction is characterized by a relatively low cost and the possibility of forming effective insulating structure shells. Frames and massive walls are used as load-bearing structures, it is possible to use concrete. Taking into account the current realities, the most relevant issue is the orientation of systems to the use of domestic materials, including those capable of functioning effectively in harsh climatic conditions. Results. It was established that the properties of polyethylene foam and products based on it make it possible to recommend this material both in facade and roof insulation systems, and in systems in contact with the ground. It was found that polyethylene foam practically does not change its properties under freezing conditions down to -70 °C and in the range of sign-variable temperatures from -60 to +70 °C. With prolonged contact with water or water-saturated soil, the properties of the material are also stable. Conclusion. The use of rolled polyethylene foam is promising both in terms of the properties of the material itself and in view of the possibility of forming seamless insulating shells. The formation of seamless insulating shells creates practically impenetrable heat-vapor- and water-insulating barriers along the perimeter of the insulated object.