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Smart indoor tourist attractions, such as smart museums and aquariums, require a significant investment in indoor localization devices. The use of Global Positioning Systems on smartphones is unsuitable for scenarios where dense materials such as concrete and metal blocks weaken GPS signals, which is most often the case in indoor tourist attractions. With the help of deep learning, indoor localization can be done region by region using smartphone images. This approach requires no investment in infrastructure and reduces the cost and time needed to turn museums and aquariums into smart museums or smart aquariums. In this paper, we propose using deep learning algorithms to classify locations based on smartphone camera images for indoor tourist attractions. We evaluate our proposal in a real-world scenario in Brazil. We extensively collect images from ten different smartphones to classify biome-themed fish tanks in the Pantanal Biopark, creating a new dataset of 3654 images. We tested seven state-of-the-art neural networks, three of them based on transformers. On average, we achieved a precision of about 90% and a recall and f-score of about 89%. The results show that the proposal is suitable for most indoor tourist attractions. [ABSTRACT FROM AUTHOR]

This study introduces a new software, cLASpy_T, that helps design models for the automatic 3D point cloud classification of coastal environments. This software is based on machine learning algorithms from the scikit-learn library and can classify point clouds derived from LiDAR or photogrammetry. Input data can be imported via CSV or LAS files, providing a 3D point cloud, enhanced with geometric features or spectral information, such as colors from orthophotos or hyperspectral data. cLASpy_T lets the user run three supervised machine learning algorithms from the scikit-learn API to build automatic classification models: RandomForestClassifier, GradientBoostingClassifier and MLPClassifier. This work presents the general method for classification model design using cLASpy_T and the software's complete workflow with an example of photogrammetry point cloud classification. Four photogrammetric models of a coastal dike were acquired on four different dates, in 2021. The aim is to classify each point according to whether it belongs to the 'sand' class of the beach, the 'rock' class of the riprap, or the 'block' class of the concrete blocks. This case study highlights the importance of adjusting algorithm parameters, selecting features, and the large number of tests necessary to design a classification model that can be generalized and used in production. [ABSTRACT FROM AUTHOR]

The design of segmental geosynthetic mechanically stabilized walls with masonry block facing is often governed by the loads that develop at the connection between the facing and geosynthetic. Yet the current understanding of the mechanisms involved in the mobilization of such connection loads is, at best, incomplete. The testing apparatus developed as part of this study facilitates simulating the transference of stresses at the face and evaluating the facing connection loads in geosynthetic-reinforced soil walls. This study assesses the connection loads between a geogrid reinforcement connected frictionally to modular concrete blocks. A comprehensive instrumentation program was implemented to capture lateral earth pressures, geosynthetic strains and loads acting at the geogrid-block connection in a geosynthetic-reinforced unit cell subjected to incremental surcharge stages. Results indicate that conventional calculations, based on earth pressure theory, may underestimate the facing connection loads, mainly when the connection loads are triggered by the differential settlement of the backfill relative to the block facing. When this mechanism dominates the mobilization at the connection, reinforcement loads increase as the differential settlement increases, developing down-drag forces at the connection between the geogrid and modular blocks. • Facing connection loads should not be understood only as a result of earth pressures. • Relative settlements between block facing wall and backfill soil cause a down-drag deformation of the reinforcement. • Down-drag deformation of the reinforcement induces significant connection loads. • The magnitude of connection loads increases with the magnitude of down-drag deformation. • Facing connection loads can be greater than the maximum reinforcement tensile load. [ABSTRACT FROM AUTHOR]

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This paper presents new mixed-integer linear programming formulations for multi-activity shift scheduling problems (MASSP). In these formulations, the rules governing shift feasibility are encoded in block-based state-expanded networks in which nodes are associated with states and arcs represent assignments of blocks of work or break periods inducing state transitions. A key advantage of these formulations is that for the anonymous MASSP in which all employees are considered as equal only a single network with integer flow variables is needed as long as the network encodes all shift composition rules. A challenging aspect is that the networks can become very large, yielding huge models that are hard to solve for large problem instances. To address this challenge, this paper proposes two exact modeling techniques that substantially reduce the size of the model instances: First, it introduces a set of aggregate side constraints enforcing that an integer flow solution can be decomposed into paths representing feasible shifts. Second, it proposes to decouple the shift composition from the assignment of concrete activities to blocks of work periods, thereby removing a large amount of symmetry from the original model. In a computational study with two MASSP instance sets from the literature dealing with shift scheduling problems, we demonstrate the effectiveness of these techniques for reducing the both size of the model instances and the solution time: We are able to solve all instances, including more than 70 previously open instances, to optimality–the vast majority of them in less than 30 min on a notebook computer. [ABSTRACT FROM AUTHOR]

Residential bathroom drainage noise is a primary source of indoor noise that directly affects quality of life and physical and mental health. Therefore, based on the acoustic theory and the finite element simulation technology, this paper proposes a method to simulate the drainage noise characteristics and its impact range jointly using the flow and acoustic fields. The pressure at the pipe wall caused by the internal flow field of the bathroom drainage pipe is calculated by the Fluent software. Simulations are carried out with the Virtual Lab software to predict the drainage noise characteristics and spatial distribution and to analyse the influence of factors such as the door position, riser position, and the partition wall material on the noise distribution. The results show that drainage noise has prominent high-frequency characteristics, the position of the bathroom drainage pipes and doors affects the spatial noise distribution, and the sound insulation performance of a partition wall with ordinary fired bricks in the bathroom is slightly better than that of ordinary concrete bricks, lightweight aggregate concrete blocks or fly ash blocks. This paper provides a theoretical basis and practical reference for reducing the impact of residential drainage noise and creating a healthy and comfortable indoor acoustic environment. [ABSTRACT FROM AUTHOR]

Seawalls are constructed by covering and protecting the sloping seashore ground with concrete plates or blocks. Their purpose is to sustain high waves induced by strong winds and prevent ground erosion, but they often collapse, mobilising different modes of failure, including that of the ground. Nevertheless, limited research has been conducted on ground failure caused by high waves. In this study, a series of novel centrifuge model tests was first conducted to investigate the failure mechanisms of seawalls due to wave propagation, focusing on the failure of the ground. Finite-element analyses were subsequently conducted to explore the failures observed in the model tests and to provide further insight as to the state of the ground leading to failure. Two failure modes were demonstrated to prevail: floating of the covering panel and sliding failure of the ground. In addition, of the possible causes of failure, the following three were identified in the current study: increased unit weight and reduced suction from wetting; enhanced seepage force under the panel and around the toe block during backwash; water pressure on the back of the panel and the landward side of the toe block during backwash. [ABSTRACT FROM AUTHOR]

This paper introduces an LC resonator-based single-frequency eddy current (EC) sensor designed for corrosion detection in reinforcing bars (rebars) embedded within concrete structures. The work addresses the challenges of the limited detection ranges and reduced sensitivity over longer distances, prevalent in current EC sensor applications. The sensor development process involved a systematic experimental approach to carefully selecting each parameter in the LC resonator. The sensor design aimed to assess the condition of the rebar from a distance of up to 5–6 cm outside the concrete and provide insights into different corrosion levels. By examining the characteristics of the inductors, the parallel resistance R p of the eddy current coil was identified as a key parameter reflecting the corrosion conditions in the rebar. The relationship between the R p fluctuations and temperature variations was investigated, with the data indicating that an approximately 155 Ω variation can be expected per 1 °C change within the temperature range of 20–25 °C, allowing for temperature compensation if necessary. Subsequently, the sensor's performance was evaluated by placing a rebar within a concrete block, where controlled mechanical degradation cycles were applied to simulate uniform corrosion in the rebar. The experimental results show that our EC sensor can detect material loss around the rebar with accuracy of approximately 0.17 mm. [ABSTRACT FROM AUTHOR]

The issue of early-age concrete cracking is challenging and relies on the state of concrete soon after it is placed in the formwork. The concrete state is a function of the strains associated with thermal and other dilatations and the level of in situ strength. Both strain and strength primarily require information on the temperature–time history of the concrete element. For larger elements, the thermal history varies significantly across the thickness and the concrete material itself acts as confinement for discrete elements. Due to complexity of this issue, designers currently rely on mock tests and/or finite-element (FE) modelling for structures that are deemed 'important'. Both approaches are costly and time consuming. It is therefore important to have a robust yet simple model to estimate the temperature variation experienced by concrete elements. The proposed spreadsheet-based model presented in this paper aims to provide a rapid estimate of the temperature profiles within a hydrating concrete element. The model uses the concept of effective thickness and the revised heat compensation technique. It was validated based on the measured temperature development of a concrete block of rectangular section. The proposed model was also successfully compared with output from FE software (TNO Diana). [ABSTRACT FROM AUTHOR]

Understanding the behavior of structures during earthquakes is crucial for ensuring safety. Despite their significant impact on buildings, infill walls are often overlooked in seismic assessments, contributing to the complexity of a structure. Because of their intricate nature and modeling difficulties, infill walls are frequently excluded from seismic models. However, given the prevalence of reinforced concrete buildings with various infill wall materials in earthquake-prone areas, it is essential to incorporate infill walls for a more realistic evaluation of seismic behavior. This study scrutinizes a building that sustained damage in the Izmir earthquake in Turkey. The building was represented in four distinct models using the SAP2000 V24 finite element program: without infill walls, with porotherm clay blocks, burnt clay brick, and autoclaved aerated concrete blocks. Real parameters of the building were utilized in the modeling process. Upon comparing the results of the time history analysis, it was observed that the presence of infill walls had a positive impact on various building properties, including period, ground floor shear force, column bearing capacity, and inter-story drift ratio. Additionally, infill walls increased base shear forces on the ground floors and the overall base shear force. Notably, similar outcomes were obtained with porotherm clay blocks and burnt clay brick as infill wall types, while autoclaved aerated concrete blocks exhibited lower stiffness than other infill wall models. [ABSTRACT FROM AUTHOR]

Slurry-infiltrated fiber concrete (SIFCON) has excellent potential for application as a new material with good crack resistance, impact resistance, and seismic performance. In this paper, SIFCON blocks were cast in a single pour using the custom-made two-dimensional directional steel fiber placement device, followed by compressive testing. Based on the test results, the effects of fly ash substitution rate, steel fiber aspect ratio, and steel fiber volume fraction on the compressive bearing capacity and ductility of SIFCON blocks were investigated. The results indicate that the custom-made device in this paper effectively achieves the directional placement of steel fibers, offering a cost-effective solution that optimizes the construction process. Regarding the test results, it was observed that the compressive bearing capacity of SIFCON blocks decreases linearly with increasing fly ash substitution rate, while the addition of fly ash improves the ductility of the blocks. Notably, a 31% decrease in bearing capacity was noted when the fly ash substitution rate increases from 0% to 40%, whereas the ductility ratio increased by 99% for the same substitution rate range. Furthermore, the results revealed a positive correlation between the bearing capacity and ductility of SIFCON blocks with higher steel fiber aspect ratios and volume fractions. Specifically, the bearing capacity increased by 19% and 33% with steel fiber aspect ratio increments from 33 to 70 and volume fraction increases from 10% to 14%, respectively. Additionally, the ductility ratio of the test blocks increased by 104% when the aspect ratio of the steel fibers increased from 33 to 70, and by 37% when the volume fraction of steel fibers rose from 10% to 14%. [ABSTRACT FROM AUTHOR]

This paper studies the impact of half-height infilled walls on the failure modes of frame columns through quasi-static tests of both frame models and half-height infilled wall frame models. Based on the experimental results, a seismic analysis model of reinforced concrete (RC) frame structures is established, and parametric studies are carried out to analyze the effects of masonry materials and masonry heights on the seismic performance of structures. The results show that the load-bearing capacity and stiffness of the structure are improved, while the ductility of the structure is reduced because of the existence of infilled walls. As the height of infilled walls increases, there is a notable decrease in the free height of frame columns. At a wall-to-column height ratio of 0.2, the masonry walls exert a negligible effect on the frame structure's seismic performance. In contrast, at a ratio of 0.6, there is a transition in column failure modes from bending to shearing. When evaluated at consistent masonry heights, aerated concrete block-infilled walls demonstrate the least impact on the seismic performance of RC frame structures. Thus, in the absence of additional structural enhancements, the use of aerated concrete blocks is recommended to mitigate the negative implications of infilled walls on the seismic integrity of RC frames. [ABSTRACT FROM AUTHOR]

In the distinct element method (DEM), a structure is modeled as an assembly of rigid elements, and the failure of the structure is represented by the breakage of the springs that connect the elements. The original DEM has a drawback in that spring constants cannot be theoretically determined. The refined DEM solved this problem and made the spring constant possible to be theoretically determined from material properties. However, the refined DEM still has a drawback in that the Poisson effect cannot be considered, and it cannot represent the tensile stress/strain and tensile failure in the orthogonal direction of the compressive force. This study proposes a method to introduce the Poisson effect into the refined DEM that can consider tensile stress/strain or tensile failure due to the Poisson effect. Since the non-diagonal component of the elasticity tensor expresses the Poisson effect, the Poisson effect is introduced using the element stiffness matrix developed using the non-diagonal component of the elasticity tensor. Through numerical analysis of the compression test of a concrete block, it was confirmed that the Poisson's ratio value was quantitatively reproduced, and tensile cracks were qualitatively reproduced. [ABSTRACT FROM AUTHOR]

Mortar that is typically employed for interior or exterior coatings can be characterised using laboratory-prepared specimens according to specific test standards; however, its performance undergoes changes following application on substrates. When selecting mortar, it is vital to anticipate its in-service behaviour after its application on substrates to make the most informed choice. Most of the research work carried out to date analyses the characteristics of mortar in laboratory specimens. Some studies analyse these characteristics after its application to support, but very few exist that compare both behaviours. With this objective in mind, this research determined the properties of mortar when cured within laboratory moulds and assessed the behaviour of the same mortar after application on diverse substrate types. This study specifically evaluated the behaviour of a pre-dosed hydraulic lime mortar when applied on concrete blocks, lightweight concrete blocks, concrete slabs, hollow ceramic bricks, and solid ceramic bricks. Later, this behaviour was compared to the same type of mortar hardened in laboratory moulds and the same type of mortar applied on substrates and subjected to accelerated ageing. Moreover, data from previous experimental work were used to compare the behaviour of the pre-dosed hydraulic lime mortar with that of pre-dosed cement mortar when applied on similar substrates. The research drew upon a comprehensive characterisation of the physical and mechanical parameters of mortar, revealing that the performance of these types of mortar undergoes significant changes after application on substrates under in-service conditions, mainly when applied on more porous substrates. It was concluded that the application of mortar to substrates increased bulk density, decreased open porosity, enhanced compressive strength, and resulted in faster capillary absorption. For mortars subjected to accelerated ageing, a notable reduction in water vapour permeability was observed, which was attributed to changes in the pore profile. [ABSTRACT FROM AUTHOR]

Mortar bedding is a high cement-based material placed between concrete blocks and can improve the tensile and shear strength of the joints. Two types are recommended, full bedding, which covers the entire liquid area of the block, and face shell bedding, where the mortar is placed only on the longitudinal walls of the block, forming a lateral cord. The union of the lack of technical regulation on the choice of the laying pattern and the execution of a wall by more than one professional, in some cases, results in the appearance of a third pattern, mixed bedding, the rows mix the full bedding and the face shell bedding types. This paper aims to evaluate the influence of the mortar bedding on the mechanical behavior of the structural masonry, where walls of concrete blocks with face shell and full and mixed bedding were made, evaluating their respective failure modes. The inputs of the wall and the structures of each proposed bedding type were individually studied and subjected to the compressive strength test. Some LVDTs have been used to evaluate and compare the displacements between patterns. In addition, the failure modes in each type of mortar bedding were analyzed. The results of the compression tests of the walls showed that the type of laying significantly influences the compressive strength of the masonry, with the face shell and mixed bedding patterns showing a loss of capacity of compressive strength in relation to the full bedding of approximately 18.5% and 21.7%, respectively. In addition, it was noted that in addition to being less resistant, the mixed pattern failed at the end of the elastic zone, demonstrating a brittle behavior. Given the facts, the full and face shell bedding is indicated; the face shell bedding is used with caution, considering its reduced load capacity and failure mode, when dimensioning the masonry. [ABSTRACT FROM AUTHOR]

The purpose of this research is to investigate the utilization potential of recycled powder made from spent coffee grounds (SCGs) and aerated concrete blocks (ACBs) in green-growing concrete. The green-growing concrete is prepared using ACB powder and SCG ash as raw materials instead of 5%, 15%, and 25% and 5%, 10%, and 15% cement, respectively. Then, the two raw materials are compounded with the optimal content. The compressive strength and alkalinity of green-growing concrete at 7d and 28d and the frost resistance after 25 freeze–thaw cycles at 28d are studied. The results showed that the optimum content of ACB powder and SCG ash was 5%. Replacing 5% cement with recycled powder could improve the strength of concrete. The alkalinity of concrete containing ACB powder gradually increased, while the alkalinity of concrete containing SCG ash gradually decreased. The alkalinity of ACB-SCG powder was lower than that of ACB powder but slightly higher than that of SCG ash. The frost resistance of concrete containing ACB powder decreased gradually, and the frost resistance of concrete containing SCG ash increased first and then decreased greatly. The frost resistance of ACB-SCG powder could neutralize that of ACB powder and SCG ash. [ABSTRACT FROM AUTHOR]

Glass fiber-reinforced polymer (GFRP) anchor bolts are a new type of high-performance nonmetallic anchor with significantly higher tensile strength, a lighter weight, better corrosion resistance, and a lower cost than steel bars. Therefore, exploring the durability and bonding performance of GFRP anchor systems is of great importance for the structural design of protective engineering, especially in coastal environments. However, insufficient research has been conducted on the durability of GFRP resin bolts in seawater conditions, with no universal standard on the pullout testing of GFRP bolts. To study the durability and bonding performance of GFRP resin bolts, durability experiments were conducted in this work using artificial seawater, and the pullout tests were conducted using a large-scale concrete platform with different compressive strengths (21.2, 40.8, and 61.3 MPa). The results of the durability experiments indicated that the strength variations of the GFRP rods and epoxy resin materials in artificial seawater environments were less than 5%. Subsequently, indoor pullout tests using steel tubes filled with epoxy resin were conducted, and the test results indicated a critical anchor length value. Pullout tests of the GFRP resin bolts embedded in large-scale concrete blocks were also conducted with different strengths. According to the test results, all GFRP resin bolts embedded in the three concrete blocks with different compressive strengths exhibited rod fracture failure. The failure mode was not controlled via the compressive strength of the concrete blocks due to the high bonding strength between the resin and the rod, as well as between the resin and the concrete. Therefore, this GFRP resin anchor system could fully utilize the tensile strength of GFRP rods. This research offers significant practical value in verifying the safety and reliability of GFRP resin bolts in corrosive marine service environments, and it contributes to the application and development of GFRP materials in the engineering field, serving as a valuable reference for the structural design and further study of GFRP bolts. [ABSTRACT FROM AUTHOR]

As a fact of matter, the aim of this paper is to produce a new ecological mortar based on recycled aggregates from hollow concrete blocks waste and reinforced with natural Diss fibers for use in manufacturing filling materials and masonry blocks, for the purpose of reducing the impact of such waste on the environment on the one hand, and making the most of the Diss plant, which is abundant in Algeria, on the other. In virtue of which, for achievement purpose of this work, we partially substituted the crushed-stones sand (CS) of a mortar reinforced with Diss fibers with recycled sand (RS) from hollow concrete blocks waste at rates of 15%, 30% and 50%. Besides, the produced mortars were subjected to density, consistency and air occlusion tests in their fresh state; moreover, they have alike been subject to compressive strength, flexural tensile strength, water absorption by immersion and capillary action, chemical resistance to acid and alkali, and chloride ion penetration tests in the hardened state. As consequence, the results illustrated improvements in consistency, mechanical strength and resistance to chemical attacks, with a slight increase in chloride ion penetration. [ABSTRACT FROM AUTHOR]

Aim of the study is to analyze the effect of pavement reflectance and aspect ratio on air and surface temperature reductions in a scale model of an urban canyon. The model, named PAVSCAM (PAVement and Street CAnyon Model), consists of two sets of four lanes disposed between concrete blocks, with 5 m in length and 1.2 m in width, which are covered with different paving materials. Hollow concrete blocks serve as 'buildings' whereas the lanes are regarded as 'streets'. Two sets of lanes are used for testing H/W ratios of 0.33 and 0.66, for block heights of 40 cm and 80 cm, respectively. Interlocking, semi-permeable concrete paver blocks were tested, in light and dark gray, against asphalt used as a reference. Thermocouples were used to assess air and surface temperature at canyon height and on the ground, respectively along with the air temperature measured at "pedestrian height". Results allowed us to infer on the interplay of thermal properties, aspect ratios, and surface reflectance, observed in measured data, and the impact of shading during two monitoring rounds in spring at a tropical location (at 22°17'00"S, 47°07'00"W) characterized by a Koeppen-Geiger's Aw climate classification. PAVSCAM proved to be effective in studying microclimate phenomena in a simplified and cost-effective manner. [ABSTRACT FROM AUTHOR]

The equivalent stress block is recommended for use in the design of reinforced concrete sections to simplify the analysis of the composite behavior of concrete and steel reinforcement. In most current codes, a rectangular equivalent stress block is provided. The design parameters of the equivalent block were recommended many years ago. Due to the importance of the equivalent stress block concept, numerous investigations have been performed to increase its accuracy. In the current paper, an exploration of the rectangular equivalent stress block has been carried out using the energy modeling approach. Energy modeling is a new general approach for studying the behavior of concrete elements. In this method, the energy consumed (work done) can be determined by integrating the force-displacement diagram (in the current study this will be the concrete stress-strain curve in compression). Schematic and equivalent stress-strain curves for concrete in uniaxial compression provided in most current codes and relevant textbooks were considered in this research. The codes taken into account in the current study are ACI-318-19, Canadian Code CSA A23.3-04, Eurocode EC-2, and Chinese standard GB 500 10 - 2002. The energy consumed by these curves for different values of concrete strength has been compared with numerous experimental results. This comparison shows that the results of the equivalent stress block provided in most of the considered current codes are conservative. Applying the energy modeling for the considered experimental stress-strain curves a modified equivalent stress block is recommended for practical use. The results of the proposed equivalent stress block are in good agreement with the experimental ones. The ratio between the predicted total energy engaging the proposed model and the total energy calculated for the experimental results ranges between 0.95 and 1.08 with a mean value equal to unity. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the impact of service conditions on lightweight partitions in residential buildingsusing life-cycle assessments (LCAs). Three alternative service conditions were included as follows: light/moderate, standard, and intensive. LCAs were conducted for pairwise comparisons among three types of lightweight partitions: gypsum board, autoclaved aerated blocks, and hollow concrete blocks. The functional unit considered was 1 m2 of a partition, and the building's lifespan was 50 years. In light/moderate conditions, the replacement rate for all three partitions was zero times during the building's lifespan. In standard conditions, the replacement rate for gypsum board and autoclaved aerated blocks was one time during the building's lifespan, and for hollow concrete blocks, it was zero times. In intensive conditions, the replacement rate for gypsum board was four times during the building's lifespan, that for autoclaved aerated blocks was two times, and that for hollow concrete blocks was zero times. The six ReCiPe2016 methodological options were used to estimate environmental damage using a two-stage nested analysis of variance. The results showed that, in light/moderate and standard conditions, gypsum board was the best alternative, while in intensive conditions, hollow concrete blocks were the best alternative. In conclusion, the choice of lightweight partitions should be made while taking the service conditions in residential buildings into account. [ABSTRACT FROM AUTHOR]

The corrosion resistance of FRP-reinforced ordinary concrete members under the combined action of harsh environments (i.e., alkaline or acidic solutions, salt solutions) and freeze-thaw cycles is still unclear. To study the mechanical and apparent deterioration of carbon/basalt/glass/aramid fiber cloth reinforced concrete under chemical and freeze-thaw coupling. Plain concrete blocks and FRP-bonded concrete blocks were fabricated. The tensile properties of the FRP sheet and epoxy resin sheet before and after chemical freezing, the compressive strength of the FRP reinforced test block, and the bending capacity of the prismatic test block pasted with FRP on the prefabricated crack side were tested. The deterioration mechanism of the test block was analyzed through the change of surface photos. Based on the experimental data, the Lam-Teng constitutive model of concrete reinforced by alkali-freeze coupling FRP is modified. The results indicate that, in terms of apparent properties, with the increase in the duration of chemical freeze-thaw erosion, the surface of epoxy resin sheets exhibits an increase in pores, along with the emergence of small cracks and wrinkles. The texture of FRP sheets becomes blurred, and cracks and wrinkles appear on the surface. In terms of failure modes, as the number of chemical coupling erosion cycles increases, the location of failure in epoxy resin sheets becomes uncertain, and the failure plane tilts towards the direction of the applied load. The failure mode of FRP sheets remains unchanged. However, the bonding strength between FRP sheets and concrete decreases, resulting in a weakened reinforcement effect. In terms of mechanical properties, FRP sheets undergo the most severe degradation in the coupled environment of acid freeze-thaw cycles. Among them, GFRP experiences the largest degradation in tensile strength, reaching up to 30.17%. In terms of tensile performance, the sheets rank from highest to lowest as follows: CFRP, BFRP, AFRP, and GFRP.As the duration of chemical freeze-coupled erosion increases, the loss rate of compressive strength for specimens bonded with CFRP is the smallest (9.62% in salt freeze-thaw environment), while the loss rate of bearing capacity is higher for specimens reinforced with GFRP (33.8% in acid freeze-thaw environment). In contrast, the loss rate of bearing capacity is lower for specimens reinforced with CFRP (13.6% in salt freeze-thaw environment), but still higher for specimens reinforced with GFRP (25.8% in acid freeze-thaw environment). [ABSTRACT FROM AUTHOR]

In engineering practice, similar surface insulation measures are typically applied to different parts of mass concrete surfaces. However, this can lead to cracking at the edges of the concrete surface or the wastage of insulation materials. In comparison to flat surfaces, the edges of mass concrete structures dissipate heat more rapidly, leading to more pronounced stress concentration phenomena. Therefore, reinforced insulation measures are necessary. To reduce energy consumption and enhance overall insulation effectiveness, it is essential to study the specific insulation requirements of both the flat surfaces and edges of concrete separately and implement targeted surface insulation measures. Taking the bridge abutment planned for pouring in Nanjing City as the research object, this study established a finite element model to explore the effects of different ambient temperatures and different surface heat dissipation coefficients on the early-age temperature and stress fields of different parts of the abutment's surface. Based on simulation results, reasonable heat dissipation coefficients that meet the requirements for crack prevention on both the structure's plane and edges under different ambient temperatures were obtained. The results indicate that under the same conditions, the reasonable heat dissipation coefficient at the edges was smaller than that on the flat surfaces, indicating the need for stronger insulation measures at the edges. Finally, mathematical models correlating ambient temperature with reasonable heat dissipation coefficients for the structure's plane and edges at these temperatures were established, with high data correlation and determination coefficients (R2) of 0.95 and 0.92. The mathematical models were validated, and the results from finite element calculations were found to be consistent with those from the mathematical models, validating the accuracy of the mathematical models. The conclusions drawn can provide references for the insulation of similar engineering concrete planes and edges. [ABSTRACT FROM AUTHOR]

This research proposes to include different percentages of recycled polypropylene (PP) fibers and polystyrene (PS) granules in the manufacture of concrete blocks. They are thermoplastic materials widely used in industry and are characterized by their lightness, their low thermal and electrical conductivity, and their low humidity absorption coefficient, factors that improve the efficiency of constructions. The results of this study show improvements in the mechanical behavior of the blocks with these plastic additives compared to the traditional ones, along with improvements in the structural behavior of the low (2-story) and medium-height (8-story) frames. [ABSTRACT FROM AUTHOR]

Nowadays, significant research effort is being dedicated to explore environmentally friendly block materials with high strength and high-temperature resistance. Ground-granulated blast-furnace slag (GGBFS) is produced during the iron smelting waste process and can be activated to form the environment friendly alkali-activated slag cementitious material (AASCM) when mixed with alkaline activator. The aggregate consists of particles of different sizes, which are crushed and are screened using the paste of AASCM. In this study, the compressive strengths of 234 block specimens during and after high-temperature treatment were investigated. The test results showed that the compressive strength of the blocks gradually decreased slowly when the temperature was lower than 600°C, and decreased rapidly when the temperature was above 600°C. The reduction coefficient of compressive strength of the blocks during and after 900°C exposure were 14.2% ~ 28.1% and 15.3% ~ 28.7% of the ambient temperature strength, respectively. The steel fibre reduced the compressive strength loss of the blocks during and after the high-temperature exposure. With the increase of temperature, the steel fibre lost its effect gradually. Moreover, the compressive strength of the block after the high-temperature treatment was higher than that during the treatment when the strength level and temperature remained constant, the ratio was between 0.99 and 1.14. The high-temperature strength loss of the alkali-activated slag crushed aggregate concrete block was lower than that of the alkali-activated slag ceramsite concrete block. The fitted equations for calculating the compressive strength during and after the high-temperature treatment provided a basis for evaluating the fire resistance of this new type of block. The microstructure and composition of the block were analysed through scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results provide theoretical basis and data support for the application of AASCM in masonry blocks in high-temperature environments. [ABSTRACT FROM AUTHOR]

The diversity‐habitat complexity relationship has been utilised widely in conservation and biodiversity enhancement interventions, but few studies have attempted to tease apart the components of complexity that drive this relationship. The ecological engineering of seawalls is one area where this topic has advanced, albeit not often at scales relevant to fish.We constructed habitat enhancement units (Simple, Complex and Freestyle 'fish houses') out of hollow concrete blocks and installed them at the base of tropical rip‐rap seawalls. Simple and Complex fish houses were cuboid, had the same surface area and volume and included 100 holes (microhabitats). The holes in Simple fish houses were all the same size, whereas 25 size variations were used in the Complex design (volume‐independent manipulation of a single complexity element). The Freestyle fish house was non‐cuboid and had more overall volume, microhabitat types and sizes.We examined the volume‐independent (Simple vs. Complex fish houses) and volume‐dependent (Freestyle fish house) effects of microhabitat complexity on fish taxonomic and functional assemblage metrics at two spatial scales and across diel cycles. We also investigated diurnal and nocturnal fish‐microhabitat size relationships.There was a modest, but not significant, volume‐independent effect of complexity on fish assemblages. The Freestyle design, however, supported significantly greater abundance, species richness, and distinct taxonomic and functional compositions. These results were dependent on spatial scales and diel cycles. Diel variation in fish activity patterns resulted in stronger size‐matching relationships between fish and microhabitats at night than during the day.Synthesis and applications. Our study shows that, to enhance fish diversity, it is important to provide three‐dimensional habitat architecture that incorporates a wide range of microhabitat sizes and types. Our findings also highlight some key considerations when assessing the performance of intervention designs, including spatial‐scale dependent effects of structural complexity, diel variation in fish‐microhabitat relationships, and choice of intervention assessment metric (i.e. taxonomic vs. functional diversity). [ABSTRACT FROM AUTHOR]

The pull-out test is one of the common experiments to determine the bond strength. When the problem is modeled in the context of linear elasticity for a cylindrical reinforced concrete block, the resulting simplified 1-D model yields so-called pull-out paradox Rezaei et al. (Mech Res Commun 126:104015, 2022) due to extreme concentration of energy near the bar. Since the standard linear elasticity is not able to consider this high values of energy, the problem was investigated by strain-gradient elasticity solution in the work of Rezaei et al. (Mech Res Commun 126:104015, 2022). In this study, to resolve the paradoxical solution, classical finite (i.e., St.-Venant–Kirchhoff model) and strain-gradient finite elasticity solutions are presented. Each mathematical model, assuming that the material is isotropic, is derived with the principle of minimum potential energy introducing appropriate strain energy. The numerical simulations are performed by the finite element method, and it is showed that numerical solution of each model converges well. [ABSTRACT FROM AUTHOR]

This paper discusses the results of 1∶25 scale shake table tests evaluating the seismic response of multiblock tower structures (MTSs) conceived as energy storage systems. The tests described here are a part of a comprehensive research campaign involving smaller physical models, computational model validation, and the theoretical background required to compare results across scales. The 6.46-m-high MTSs consisted of over 7,000 concrete blocks stacked vertically without any bonding agent, interacting only by friction and rocking. Three MTSs were tested under two different ground motions. Dynamic digital image correlation (DIC) and low-cost micro electrical mechanical system (MEMS) accelerometers were used for dynamic response measurements. Towers 1 and 3, subjected to repeated strong-intensity earthquake ground motions, collapsed during the third repetition due to the accumulation of residual displacements. Tower 2 was subjected to a single near-fault ground motion representing an extreme event and collapsed during the test. Different collapse mechanisms were identified in the test program. Data collected from individual blocks showed in-plane and out-of-phase block rotation and sliding, which contributed to the system's energy dissipation during the tests. [ABSTRACT FROM AUTHOR]

The pursuit of development in an economically sustainable and ecologically sound manner is a goal of modern society. It has been investing in products that minimize their environmental impact, particularly concerning the use of plastic. This material is highly detrimental to nature due to its toxicity and long decomposition period. The present study aims to analyze the feasibility of producing blocks made of concrete with different amounts of waste plastic taken from coastal and estuarine areas. After laboratory analysis, it was found that blocks containing 5% plastic exhibit good compressive strength and are lighter. Additionally, there was an increase in the acidity of the sample, a decrease in the density of the block, and reductions in both flexural and compressive strength. The prototype, composed of 5% plastic by mass, proves to be efficient for constructing single-story houses. It meets the minimum requirements for normative resistance, effectively encapsulating the plastic within the block and thereby reducing its environmental impact. [ABSTRACT FROM AUTHOR]

The construction sector must incorporate the circular economy to improve sustainability and efficiency. The use of recycled aggregates (RAs) as a substitute for natural aggregates (NAs) is currently being investigated and is expected to yield considerable benefits in the future. The objective of this research is to evaluate the environmental and economic benefits of using recycled coarse aggregates (RCAs) in different 1 m3 samples of concrete, substituting the natural coarse aggregate (NCAs) with RCAs in different percentages. RCAs generally come from the treatment of construction and demolition wastes (CDWs). However, in this research, the RCAs are the concrete block wastes (CBWs) generated by a concrete production plant. Among the most notable results is that compared to concrete with no RCAs, using alternatives in which RCAs have replaced 50% of the NCAs leads to an average decrease in impact category statistics of −3.30%. In contrast to the existing literature on the subject, the process of producing RCAs generated efficiency improvements in categories such as abiotic depletion of fossil fuels (−58.72%) and global warming potential (−85.13%). This is because the transport process, a key factor in determining the viability of using RAs instead of NAs, was eliminated. In economic terms, there is a slight decrease in the financial cost of producing 1 m3 of concrete as the quantity of RCAs increases. The maximum decrease was 0.23€/m3 in the samples studied. Combining both the environmental and economic aspects resulted in a reduction factor of 0.420 g of CO2/€cent, which means fewer CO2 emissions per unit cost when using RCAs. In conclusion, these results are intended to further knowledge in the field of using RAs instead of NAs in order to help the sector achieve sustainability and find an alternative use for a particular type of business waste. [ABSTRACT FROM AUTHOR]

This paper presents the details of experimental testing of masonry prisms, which were tested in compression. The experimental program consisted of prisms made with hollow and solid blocks of thickness 100 and 150 mm. Five different proportions of mortars were employed in the casting of these prisms, which included 1:2, 1:3, 1:4, 1:5, and 1:6 by weight. Three prisms were cast and tested using each of these mortar types for each block type. It was found that the failure modes and compressive behaviors of the prisms were not significantly influenced by the mortar types, although these were different for the prisms made of solid and hollow blocks. The deformation behaviors of the prisms in the postpeak region were also different for these block types. The compressive strength of the prisms (fp) varied with the block strength and was not dependent on the block type. All the prisms exhibited typical behaviors of uniaxially compressed prismatic members. An average elastic modulus of 1,720 fp was found for the tested prisms, while Poisson's ratio varied from 0.10 to 0.15. Analytical models for estimating fp and strain corresponding to fp have been proposed for design practice. A new constitutive equation for capturing the falling branch of the stress–strain curve of block masonry prisms has also been proposed. [ABSTRACT FROM AUTHOR]

In this study, without using any uniaxial force and bending moment (N-M) interaction diagrams, designs were carried out on thick columns subjected to uniaxial bending and compression by a novel 1 dimensional (1D) Fuzzy Inverse Logic (FIL) method. For this purpose, firstly, a Fuzzy Logic (FL) model was developed and the FIL method was applied to it thereafter. While, the cross-section width (b), the cross-section height (h), the rebar diameter(f), the numbers of reinforcement rows (Rx and Ry) placed into the cross-section in X and Y directions, the characteristic concrete compressive strength(fck) and the axial force ratio Nr=N/(b.h.(fck/1.5)) were taken as variable parameters, concrete cover thickness (c), rebar strength (fyd) and k1 parameter defined for the concrete pressure block were kept constant in the developed FL model. After designs were performed on 15 columns having different variable variations by the 1D FIL method, moment bearing capacities of the obtained 9737 alternative designs determined conventionally were compared with the desired moment values. The evaluations made on the comparisons show that the FIL method is not only a very effective artificial intelligence method for the design of reinforced concrete thick columns but also a promising method for many other problems such as control, optimization, design, etc. [ABSTRACT FROM AUTHOR]

This study focuses on the characterization of low-velocity (lower than 100 km/h) rockfall impact loads transferring to a thick steel-reinforced concrete (SRC) slab through a protective sand layer. A full-scale experimental test campaign was performed, where each test consisted of releasing a concrete block which, after a vertical free fall, impacts a sand protective layer placed over a SRC slab, in order to represent an isolated rockfall impact to which an actual SRC structure could be exposed. During the impact, the vertical pressure distribution was observed using several pressure cells installed at the sand–slab interface. A total of 35 tests were carried out, systematically combining sand layer thickness (D), block's equivalent diameter (B), and free-fall drop height (H), related to impact velocity. The masses of the released blocks were in the range of 117 to 7,399 kg, corresponding to diameters in the range of 0.42 to 1.79 m. Five free-fall drop heights up to 33 m were considered to reach impact velocities up to 90 km/h , covering the range of most velocities observed in actual rockfall studies. Three thicknesses of the sand layer protecting the thick SRC slab were considered: 1, 1.5, or 2 m. Data reduction from this full-scale impact tests program makes it possible to characterize, for a given thickness of protective sand layer, the time-space pressure pulse distribution applied to the protected structure during the impact for a large range of rock boulder masses and speeds actually observed in the field. [ABSTRACT FROM AUTHOR]

For the safe transmission of loads to concrete supports, such as column-foundations, corbels, bridge pedestals, post-tension members, support anchorages, and other forms of superstructure supports, the concrete bearing strength is considered an essential design parameter. The usage of recycled aggregate within concrete is considered environmentally friendly since it diverts rubbish from bulldozing and preserves natural resources. End-hooked steel fibre is an almost substantial enhancer for recycled aggregate concrete characteristics. Never before has the bearing behavior of recycled aggregate concrete been evaluated. Thus, this study provides an experimental evaluation of the bearing strength of steel fiber-reinforced recycled aggregate concrete at different replacement levels (0, 10, 20, 30, 50, and 100%) of recycled concrete aggregate (RCA). The used fraction quantities of steel fiber were 0.5%, 1.5%, and 2%. Three sizes of blocks were manufactured (100 × 100 × 100 mm, 150 × 150 × 150 mm, and 250 × 250 × 250 mm). The ratio of concrete block area to bearing area (A2/A1) was kept constant at 2.5 for all three block sizes. The primary purpose of this research was to examine the impact of block size on bearing stiffness, ultimate slip, and ultimate bearing strength. The findings demonstrated that the bearing stiffness and bearing strength reduced as the block size increased. To assess the ultimate bearing stiffness/strength and normalised ultimate bearing slip, analytical models were employed to develop new proposed equations that unaccounted for the impact of compressive strength, RCA, reinforcing index of steel fibre, and block size. In addition, this research led to the creation of a modified ACI 318 formula that accurately forecasts the bearing strength of concrete depending on block size. [ABSTRACT FROM AUTHOR]

The issue of significant floor heave deformation in gob-side entry retaining has long been a challenging problem in the context of longwall mining. This paper studies the floor heave failure mechanism and control method for gob-side entry retaining with concrete blocks in Guizhou Faer Coal Mine in China. Based on Rankine's earth pressure theory, the effective shear stress equation for the plastic slip of roadway floor is established. The deformation mechanism of floor heave in a retaining roadway with a block wall is revealed in this study. The new comprehensive control method is proposed, encompassing roof pre-splitting blasting for pressure relief, reinforcing cables for roof control, double directions control bolts for concrete block, and pliability cushion yielding pressure. FLAC3D numerical calculation model is established, which shows that the new method can effectively reduce the average vertical stress peak value of the entity coal floor by 34.6% and significantly reduce the pressure source causing the roadway floor heave. Besides, a multi-parameter real-time online monitoring system for mine pressure was designed, and field tests were carried out. The results show that the maximum value of roadway floor heave under the new method is 163 mm, reduced by 66.9%, and the roadway floor heave is effectively controlled. These research findings offer a fresh perspective and new ideas for controlling floor heave in mining operations. [ABSTRACT FROM AUTHOR]

This paper reports an experimental campaign to evaluate the residual mechanical resistance after high temperatures of two structural masonry components: block and mortar. Residual compressive strength and deformation modulus of four different hollow concrete blocks and two different mortar mixes after heating at high temperatures are investigated. The test method used was the one recommended by RILEM TC 200 for mortars and an adaptation of the same method proposed by Medeiros et al. suitable for the geometry of hollow blocks. Despite the sharp drop in the deformation modulus after heating blocks and mortar, no different behaviours are observed in the deformability of the materials caused by the variables studied. The same cannot be said in relation to the variation of the residual compressive strength of the blocks, which is affected by the variables: initial nominal compressive strength and width of the concrete block. Regarding laying mortars, the results confirmed the small influence of compressive strength on the evolution of residual mechanical strength. The data and analyses reported here on the residual mechanical properties of hollow concrete blocks produced from a concrete mixture of very dry consistency, vibro‐pressed and with normal weight aggregates are relevant, since the data found in the literature generally refer to the wet cast concrete material and in cylindrical bodies. [ABSTRACT FROM AUTHOR]

Fire is a significant threat to human lives and the integrity of buildings. To better understand the complex behavior of masonry exposed to high temperatures, thermal analyses were carried out to evaluate the temperature distribution in concrete blocks and stack-bond prisms exposed to high temperature levels. The effects of distinct specimen boundary conditions (restrict or easy access to air circulation inside the voids of the block and prisms) on the thermal response of the masonry materials were investigated. Thersys 2.0 software was used to implement three-dimensional thermal analysis of distinct finite element models. Four-node tetrahedral elements and full integration were used in all models. The modeling approach was validated by experimental data obtained from thermocouples embedded into masonry components. The results indicated that the boundary conditions significantly affected the time required for homogenization of temperature in blocks and prisms. Easy access to air circulation inside the voids of the prisms provided a faster temperature homogenization. In this scenario, the prism reached temperature ranges of (300 ± 0.5% × 300) °C and (600 ± 0.5% × 600) °C after exposure times of 2 h and 2 h 10 min, respectively. When access to air circulation within the voids of the prisms was limited, the same temperature ranges were achieved after exposure times of 5 h 20 min and 6 h, respectively.