Abstract The incorporation of a single fiber into engineered cementitious composites (ECC) has relatively limited effects on improving their performance. To further enhance the physical and mechanical behaviors of ECC and improve their durability, steel–polyethylene hybrid fiber reinforced engineered cementitious composites (ST/PE-HFRECC) specimens were prepared by mixing steel fibers and polyethylene (PE) fibers by different volume fractions. Using a split Hopkinson pressure bar (SHPB), dynamic compression tests were conducted under three different loading rates. The effect of loading rate and fiber volume fraction on the dynamic compression behaviors of ST/PE-HFRECC was investigated. Based on the experimental results the following conclusions can be obtained: (1) The dynamic compressive strength, peak strain, pre-peak stress toughness, and dynamic increase factor (DIF) of ST/PE-HFRECC exhibit significant strain rate strengthening effects under dynamic loading. (2) The ST/PE-HFRECC exhibited superior dynamic performance and crack-bridging capability compared to composites reinforced solely with steel or PE fibers. Steel fibers significantly improved the dynamic compressive strength, while PE fibers better enhanced the ductility and toughness of the material. (3) Among the hybrid formulations of steel and PE fibers, the S0.5E1.5 (0.5% steel fiber and 1.5% PE fiber by volume) demonstrated optimal resistance to high rate compressive failure, reflected in reduced specimen damage, higher dynamic compressive strength, peak strain, and pre-peak stress toughness.
Systems of building construction. Including fireproof construction, concrete construction
Sergey V. Guz, Vladimir N. Kozyrev, Mikhail V. Ilemenov
et al.
This article addresses current issues related to the marking of fire hose couplings, which are essential components of fire extinguishing systems. Defects arising from various marking application methods are analyzed. Regulatory requirements (GOST R 53279-2009 and GOST 4666-2015) were examined to identify areas for improving marking practices. Specific measures are proposed to improve the regulatory framework and unify the location and methods of marking. A comparative analysis of modern marking methods (laser, dot-peen, electrochemical, etc.) was performed, assessing their resistance to environmental factors. International practices in marking fire-fighting equipment in Europe and the USA were reviewed. Scientifically grounded recommendations are formulated for selecting the application method, font, and marking location to ensure durability and readability throughout the service life. The inclusion of marking test methods in the regulatory framework is also substantiated.
Systems of building construction. Including fireproof construction, concrete construction
Vehicle-to-building (V2B) systems integrate physical infrastructures, such as smart buildings and electric vehicles (EVs) connected to chargers at the building, with digital control mechanisms to manage energy use. By utilizing EVs as flexible energy reservoirs, buildings can dynamically charge and discharge them to optimize energy use and cut costs under time-variable pricing and demand charge policies. This setup leads to the V2B optimization problem, where buildings coordinate EV charging and discharging to minimize total electricity costs while meeting users' charging requirements. However, the V2B optimization problem is challenging because of: (1) fluctuating electricity pricing, which includes both energy charges ($/kWh) and demand charges ($/kW); (2) long planning horizons (typically over 30 days); (3) heterogeneous chargers with varying charging rates, controllability, and directionality (i.e., unidirectional or bidirectional); and (4) user-specific battery levels at departure to ensure user requirements are met. In contrast to existing approaches that often model this setting as a single-shot combinatorial optimization problem, we highlight critical limitations in prior work and instead model the V2B optimization problem as a Markov decision process (MDP), i.e., a stochastic control process. Solving the resulting MDP is challenging due to the large state and action spaces. To address the challenges of the large state space, we leverage online search, and we counter the action space by using domain-specific heuristics to prune unpromising actions. We validate our approach in collaboration with Nissan Advanced Technology Center - Silicon Valley. Using data from their EV testbed, we show that the proposed framework significantly outperforms state-of-the-art methods.
Diptikar Behera, Kuang-Yen Liu, Firmansyah Rachman
et al.
Lightweight concrete (LWC) has emerged as a transformative material in sustainable and high-performance construction, driven by innovations in engineered lightweight aggregates, supplementary cementitious materials (SCMs), fiber reinforcements, and geopolymer binders. These advancements have enabled LWC to achieve compressive strengths surpassing 100 MPa while reducing density by up to 30% compared to conventional concrete. Fiber incorporation enhances flexural strength and fracture toughness by 20–40%, concurrently mitigating brittleness and improving ductility. The synergistic interaction between SCMs and lightweight aggregates optimizes matrix densification and interfacial transition zones, curtailing shrinkage and bolstering durability against chemical and environmental aggressors. Integration of recycled and bio-based aggregates substantially diminishes the embodied carbon footprint by approximately 40%—aligning LWC with circular economy principles. Nanomaterials such as nano-silica and carbon nanotubes augment early-age strength development by 25% and refine microstructural integrity. Thermal performance is markedly enhanced through advanced lightweight fillers, including expanded polystyrene and aerogels, achieving up to a 50% reduction in thermal conductivity, thereby facilitating energy-efficient building envelopes. Although challenges persist in cost and workability, the convergence of hybrid fiber systems, optimized mix designs, and sophisticated multi-scale modeling is expanding the applicability of LWC across demanding structural, marine, and prefabricated contexts. In essence, LWC’s holistic development embodies a paradigm shift toward resilient, low-carbon infrastructure, cementing its role as a pivotal material in the evolution of next-generation sustainable construction.
Mohamed Emara, Abdulrahman H. Mostafa, Heba A. Mohamed
et al.
Abstract This research investigates the flexural performance of strengthened rubberized concrete beams via bottom, side, and hybrid near-surface mounted (NSM) approaches using GFRP/steel rebars. Eleven strengthened specimens, alongside one control, were subjected to four-point loading setup till failure. The investigation focused on three key parameters: strengthening technique (bottom, side, or hybrid), NSM bar area, and bar type (GFRP or steel). The results revealed significant improvements across various performance metrics. It was demonstrated that NSM strengthening enhanced the beam’s cracking loads by up to 90%. Correspondingly, the strengthened beam’s yield and ultimate loads witnessed enhancements up to 48% and 79%, respectively. Notably, the load-carrying ability of GFRP bars consistently outperformed steel bars. Additionally, increasing the quantity of NSM strengthening proved beneficial, with bottom placement offering a slight advantage due to a larger internal lever arm. The proposed hybrid NSM technique, employing three 8-mm-diameter GFRP bars, emerged as the most effective strengthening scheme. However, utilizing four bars resulted in decreased effectiveness due to overlapping tensile stresses and accelerated debonding failure. Finally, the experimental results were compared to analytical predictions, with close agreement observed. The experimental-to-predicted analytical result ratio varies from 0.84 to 1.01%, indicating the validity of the analytical approach.
Systems of building construction. Including fireproof construction, concrete construction
Rami A. Hawileh, Sayan Kumar Shaw, Maha Assad
et al.
Abstract Fly ash (FA) offers a sustainable alternative to cement in concrete, addressing environmental concerns and enhancing sustainability in construction practices. This substitution contributes to both resource efficiency and reduced carbon footprint. This review study investigated the effect of FA on the compressive strength of ultrahigh-performance concrete (UHPC). No negative effect associated with the increase in FA replacement percentage up to 60% by weight is observed in terms of compressive strength of UHPC without superplasticizer. However, higher replacement percentages are shown to negatively affect the compressive strength. Further investigations should focus on the compressive strength characteristics and limitations associated with elevated levels of FA replacement, i.e. 60–80%. A promising behaviour associated with higher replacement percentages is observed in few studies. Moreover, the superior compressive strengths observed up to 50% FA replacement after a curing period of 90 days underscore the need for a more extensive exploration of longer curing durations. Future studies should focus on investigating the properties of UHPC beyond 90 days, as such information is currently limited.
Systems of building construction. Including fireproof construction, concrete construction
Abstract This study investigates the impact of adding nanocarbon black (NCB) to wellbore cement under high-pressure, high-temperature (HPHT) conditions to enhance its properties for long-term zonal isolation. Four cementitious slurries were prepared in the laboratory using the wet-mixing method, following the American Petroleum Institute standards (API 10B-2 and API 10A). NCB was incorporated as a reinforced nanomaterial in cementitious composites at varying concentrations of 0.05%, 0.1%, and 0.2% by weight of cement (BWOC) into the slurry mix fluid following a specific mixing sequence before the addition of Class-G wellbore Portland cement, which is manufactured via the dry process and commonly used in the oil and gas industry. The study evaluated parameters, such as density, rheology, free fluid (FF), fluid loss (FL), thickening time (TT), compressive strength (CS), tensile strength (TS), porosity, and permeability, following API standards. The results demonstrated that NCB additions slightly increased slurry density and significantly improved rheological properties, with low yield stress at bottomhole circulating temperatures. NCB concentrations of 0.05% and 0.1% reduced free fluid, fluid loss, and thickening time while enhancing the cement sheath's compressive and tensile strength, simultaneously reducing its porosity and permeability. Moreover, the improved early compressive strength development indicated accelerated cement hydration reactions due to incorporating NCB. The study found that 0.1% NCB was the optimal concentration, enhancing mechanical properties and operational efficiency by reducing wait-on-cement time and costs while improving wellbore integrity. However, higher NCB concentrations required careful dispersion to prevent nanoparticle agglomeration. Overall, NCB significantly enhanced cement sheath characteristics under HPHT conditions.
Systems of building construction. Including fireproof construction, concrete construction
Abstract During a numerical investigation conducted using ABAQUS software, various bond-slip models for the FRP–concrete interface were evaluated to accurately predict the shear contribution of FRP in strengthening reinforced concrete (RC) beams. Three established bond-slip models were chosen to develop finite element analysis models for the four FRP-strengthened beams. The outcomes of these numerical simulations were subsequently compared with experimental data. The results demonstrated a strong correlation between the finite element simulations and the experimental tests, particularly regarding the failure process and shear capacity of the reinforced beams. The increase in shear capacity observed during testing varied from 13.5% to 42.9%. In contrast, the corresponding increase in shear capacity predicted by the finite element simulations ranged from 5.5% to 47.7%. The discrepancy in CFRP shear contribution among beams with different bond-slip relationships, under identical reinforcement configurations, was observed to be within the range of 0.1% to 15.9%. The numerical results of the Nakaba model showed a higher level of safety; however, the simulation performance of the Lu model was regarded as more effective and better suited for numerical analysis in predicting the shear contribution of FRP in strengthened RC beams.
Systems of building construction. Including fireproof construction, concrete construction
Abstract This study evaluates the mechanical effects of free water in wet-state concrete under dynamic loading, applying principles from the Stefan effect. A novel model of viscous stress is introduced, incorporating pore structure characteristics for the first time. Pore structure features of both mortar and aggregate are analyzed using mercury intrusion porosimetry. Equations are developed to integrate the differential pore volume and pore diameter of mortar and aggregate, facilitating the calculation of viscosity stress coefficients. A water content model, based on pore structure and water content assessments, is proposed to determine the distribution of unbound water. The results reveal that free water, within the lognormal distribution of pore sizes, fills nearly all available pore volume. However, when pore diameters follow a power law distribution, complete filling is not achievable. The viscous stress induced by pore water is primarily influenced by freely moving water in smaller pores. When free water adheres to apertures within a specific diameter range governed by the power law, substantial viscous stress occurs. The effect of viscous stress on larger pore diameters is negligible compared to the strength of the concrete matrix. The methodology for calculating pore water viscous stress in concrete, a composite material consisting of mortar and aggregate, is clearly outlined, and the improved model aligns well with experimental data.
Systems of building construction. Including fireproof construction, concrete construction
Christian Riitamaa, Frank Markert, Luisa Giuliani
et al.
Abstract Explosive spalling of concrete is an essential phenomenon to be accounted for when analyzing the fire performance of concrete structures. Existing fire simulation tools can provide the fire exposure on the concrete surface and to some extent, conjugate heat transfer, too, but new tools are needed to model concrete high-temperature reactions coupled with heat and mass transfer. This work forms the first part of the two-part work. In Part A, we formulate a one-dimensional heat and mass transfer model to predict the internal temperature and gas pressure and verify the solver implementation using analytical solutions. Model validation is performed using experimental data for normal moisture from the research literature. In the absence of concrete chemistry details, the degradation reactions are calibrated using the measured mass loss histories, reaching a post-calibration uncertainty ≤ 0.4%. The validation results indicate that the maximum mean absolute percentage error (MAPE) for temperature predictions is ≤ 16%, bias = − 2.4% and relative standard deviation 9.1%. For the peak pore pressure, 57 ≤ MAPE ≤ 87%, averaged over depth and ignoring outliers and singular measurements. Possible reasons for the high pressure uncertainty are discussed.
Systems of building construction. Including fireproof construction, concrete construction
We introduce the notion of a Calabi--Yau quadruple as a generalization of Iyama--Yang's Calabi--Yau triple. For each $(d+1)$-Calabi--Yau quadruple, we show that the associated Higgs category is a $d$-Calabi--Yau Frobenius extriangulated category, which moreover admits a canonical $d$-cluster-tilting subcategory. Concrete examples arise from the construction of relative cluster categories and Higgs categories in the setting of ice quivers with potentials, as well as from the singularity category of an isolated singularity. As an application, we prove that both the relative Amiot--Guo--Keller's construction and the Higgs construction of a $(d+1)$-Calabi--Yau quadruple take silting reduction to Calabi--Yau reduction.
Tall buildings (TBs) are becoming increasingly prevalent in urban areas, posing unique challenges for their structural design and seismic performance. In Erbil city, flat slab construction with special reinforced concrete shear walls is commonly used in TBs, although it may not comply with international standards like ASCE7 and IBC without validation through nonlinear analysis. This study investigates the seismic performance of various seismic force-resisting systems employed in tall buildings in Erbil city, utilizing ACI318 for the design of the reinforced concrete structures and ETABS software for the analysis. Four structural systems were analyzed: Dual Systems with Special Moment Frames, Special Reinforced Concrete Moment Frames, Reinforced Concrete Ductile Coupled Walls, and Special Reinforced Concrete Shear Walls. Key structural responses, including stiffness, fundamental period of vibration, mass participation ratio, story displacement, inter-story drift ratio, story shear, and overturning moment, were examined. Dual Systems and Special Moment Frames demonstrated superior management of these parameters, thereby enhancing overall structural performance. The study underscores the importance of selecting appropriate seismic systems based on building height, with particular attention to the limitations posed by ductility and stability in taller structures.
M. Hrasnica, Amina Karavelić-Hadžimejlić, S. Medić
et al.
Extensive construction of buildings with structural system made of reinforced concrete walls had been started in the early 60s of the last century, as a continuation of the rebuild of Europe after the World War II. This was especially true in the Western Balkan region. In some way these buildings replaced multistorey masonry buildings, enabled significantly higher number of floors and a larger number of apartments. A specific construction technology with the so-called tunnel formwork was applied, which enabled rapid construction progress in terms of the height of the building. Seismic resistant structure of the buildings consisted mainly of reinforced concrete slabs and walls, whereby the reinforcement detailing was performed according to the old technical codes and the ancient state of the art of the building’s construction. Regarding the structural system, the way of the construction and structural detailing of these buildings, they can be classified as a recent historical heritage. A high-rise building in Sarajevo, with 20 residential floors, about 55 years old, with a load-bearing system made of reinforced concrete walls and slabs, almost without any beams, was analyzed. According to the modern state of the praxis, the building does not meet the requirements of contemporary seismic codes, and this especially applies to the reinforcement design and detailing. Taking into account seismic vulnerability classification of the European Macroseismic Scale the building could suffer substantial damages when exposed to the stronger earthquake motions. We tried to capture the specific design of the existing reinforced concrete walls applying more sophisticated structural models, including confined and unconfined concrete. The mechanical properties of the built-in building materials in existing slabs and walls were obtained experimentally. The results of the nonlinear analysis show a relatively satisfactory global response of the structure, but with possible damages due to the rather poor reinforcement quantity in the walls. Just to mention that some of the main structural walls possess only few longitudinal reinforcement bars in the corners. An improvement of the structural system, in order to achieve a ductile response with the dissipation of the energy introduced by the earthquake, as proposed by the latest seismic codes and recommendations, has been discussed as well.
The global construction industry faces a dual challenge: meeting the massive demand for concrete while mitigating its significant environmental footprint, primarily from cement production. Concurrently, the disposal of industrial and agricultural waste poses severe ecological threats. The integration of these waste streams such as Sugarcane Bagasse Ash (SCBA), Waste Paper Sludge Ash (WPSA), Rice Husk Ash (RHA), Fly Ash, and Waste Glass Powder (WGP) as partial cement replacements presents a promising pathway toward sustainable concrete. However, the non-linear and complex behavior of concrete incorporating these supplementary cementitious materials (SCMs) makes traditional empirical mix design methods inadequate. This paper provides a comprehensive review of the state-of-the-art in leveraging advanced Artificial Intelligence (AI) and Machine Learning (ML) models to optimize sustainable concrete mix designs. We synthesize empirical findings from numerous studies on the mechanical and durability properties of concrete containing SCBA, WPSA, RHA, Fly Ash, and WGP. Building upon this foundation, the core of this review proposes a novel multi-method AI framework. This integrated framework synergistically combines Geographic Information Systems (GIS) for spatial waste inventory and logistics, Remote Sensing for monitoring raw material availability and environmental impact, and a suite of advanced ML algorithms including Frequency Ratio (FR), Information Value (IV), Logistic Regression (LR), Artificial Neural Networks (ANN), and Weight of Evidence (WoE) to create a robust predictive and optimization model. The proposed system is designed to predict key concrete properties (e.g., compressive and tensile strength) and identify the optimal mix proportion for a given set of performance, cost, and sustainability criteria. This review underscores the transformative potential of a data-driven, AI-powered approach in transitioning the concrete industry towards a circular economy, enabling the effective Valorization of waste streams into high-value construction materials.
During the long-term operation of hydraulic structures under the action of complex loads and impacts, non-design changes occur, which lead to a decrease in the bearing capacity and safety and, accordingly, to the need for structural reinforcements. Experiments were conducted to study the strengthening of reinforced concrete models of hydraulic structures with interblock construction joints (located in two directions) and with the low longitudinal reinforcement coefficients typical of hydraulic structures (μs = 0.0039 and μs = 0.0083), using the low concrete classes B15 and B25. These structures were strengthened using external reinforcement with carbon ribbons of the FibArm 530/300 type. The results revealed an increase in the bearing capacity (by 1.355- and 1.66-fold); accordingly, the high efficiency of this strengthening method for reinforced concrete hydraulic structures was proven. Using the results of these experiments, including the obtained special characteristic of the cracking of reinforced concrete structures and the results of studies by other authors, recommendations for calculations involving reinforced concrete hydraulic engineering structures strengthened with an external reinforcement system of carbon-fibre-based composite materials were developed and proposed. Carbon-fibre-based composite materials are used as elements of external reinforcement for building structures (unidirectional—tapes, bidirectional—meshes and fabrics). The calculation recommendations proposed by the authors can be taken into account for the creation of a regulatory framework for hydropower facilities, including hydroelectric power plants and pumped-storage power plants. They justify the use of an external reinforcement system made with carbon-fibre-based composite materials to strengthen hydraulic structures in operation and provide an increased level of safety for reinforced concrete structures and constructions.