Low-cost Construction Research Articles

Utilizing waste materials in concrete: A review on mechanical and sustainable performance

The construction industry consumes more natural resources than any other sector, necessitating sustainability practices. Utilizing waste materials in concrete addresses disposal challenges while enhancing sustainability. Many waste materials possess pozzolanic properties, improving concrete performance. This review aims to examine sustainable concrete incorporating waste materials such as fly ash (FA), silica fume (SF), recycled concrete aggregate (RCA), slag (S), waste perlite powder (WPP), groundnut husk ash (GHA), and nano silica (NS). The methodology involves a comprehensive analysis of life cycle assessment (LCA) studies, country-specific waste production, and concrete performance focusing on environmental and economic impacts. Results show that FA, SF, S, WPP, and NS enhance concrete's compressive strength, with SF yielding a 41% increase at a 12% substitution rate. Additionally, substituting FA can reduce carbon dioxide (CO2) emission by 68% and combining 5% SF and 15% FA lower CO2 emission by 16% compared to reference concrete. Furthermore, combining WPP and RCA results in a 17% cost reduction compared to reference concrete, while GHA substitution decreases cost by up to 30%. These findings highlight the potential of utilizing waste materials to improve mechanical performance, reduce environmental impact, and lower construction costs. The review suggests future research directions to further improve performance.

RF electromagnetic design and multi-physics analysis of CW CH-DTL for AB-BNCT

The accelerator-based boron neutron capture therapy (AB-BNCT) facility is being developed worldwide due to its advantages, including easy maintenance, low construction costs, and high safety. To minimize both the length and cost of the accelerator, we propose a combined acceleration structure that utilizes a radiofrequency quadrupole linac (RFQ) in conjunction with a crossbar H-mode drift tube linac (CH-DTL). The CH-DTL rapidly accelerates the beam to the required energy after the RFQ, with output energy adjustable from 2.2 MeV to 3.2 MeV. We have completed the RF electromagnetic design and optimization of the CH-DTL cavity to fulfill beam dynamics requirements while achieving high effective shunt impedance. Additionally, we designed the cooling channels and conducted multi-physics analyses to evaluate the cavity's performance during continuous wave operation.

A Novel 10 MW Floating Wind Turbine Platform—SparFloat: Conceptual Design and Dynamic Response Analysis

New conceptual designs for floating offshore wind platforms (FOWPs) are crucial for deep-sea wind power generation, increasing power output, lowering construction costs, and minimizing the risk of damage. While there have been various conceptual designs, tailored solutions for the South China Sea are limited due to the relatively harsh environment. This study proposes a novel 10 MW FOWP—“SparFloat”, which combines the advantages of a semi-submersible platform and Spar platform to cater for the sea conditions of the South China Sea. By systematically adjusting the distance between columns and the diameters of the side column and heave plate, the impact of geometrical changes in the platform on its dynamic response is investigated for the purpose of design optimization. The results highlight that roll/pitch natural periods are predominantly governed by restoring stiffness, whereas heave motion exhibits a higher sensitivity to added mass and radiation damping. Increasing the inter-column distance and side column diameter enhances stability and reduces roll/pitch natural periods, while enlarging the heave plate diameter extends the heave natural period. Time-domain simulations using a coupled FAST-AQWA framework confirm that the optimized design meets rule requirements, verifying the robustness and suitability of the SparFloat concept for the challenging environment of the South China Sea.

Effect of alkali treatment and fibre length on agave/mortar composite properties

The use of natural vegetable fibres to reinforce cement and cement mortar is well studied in the literature. This paper focused on the efficient deployment of Agave americana L. fibre by using it as reinforcement in cement mortar. Two parameters that affect the mechanical properties of composites were taken into account, mainly fibre length and fibre pre-treatment. The tensile and flexural strengths of the specimens were determined. Results of this study indicated that the fibre length influences both flexural and tensile properties. When treated with 2 % NaOH, the tenacity of agave fiber passed from 32 cN/tex to 40 cN/tex and its crystallinity increased from 13 % to 44 %. The fibre length of 20 mm appeared to be the optimum value over which the flexural strength decreased due to the bundling effects of the long fibres. Besides, treating the fibres with an alkaline solution of 2 % NaOH could improve the mechanical properties of agave/mortar composite in such a way that the tensile strength increased from 4.5 MPa to 10.9 MPa for a fiber length of 25 mm. The main result of this study showed the possibility of using Agave americana L. fibres to implement low cost construction materials.

Maximum shear analysis of clay brick masonry structures for advanced design with bamboo diagonal reinforcement

Abstract The traditional rural houses in Indonesia, constructed with clay brick masonry wall, lack the usage of detailed reinforced concrete frame. Therefore, in the event of an earthquake, numerous structures made of masonry walls experience a collapse. Clay brick masonry walls require alternative reinforcement that is both accessible and readily available, such as bamboo, which is abundant in rural regions of Indonesia. The objective of this study is to analyse the behaviour of wall collapse under lateral stresses and assess the potential for enhancing the wall’s shear strength through the use of bamboo diagonal reinforcement. Bamboo is expected to be more advantageous for low-cost construction, replacing steel, particularly in the rural regions. The test findings are examined and inferences are made for the subsequent analysis phase. The analysis conducted involves the modelling of clay brick masonry walls, both with and without bamboo diagonal reinforcement, using the acquired data on material properties. The inclusion of bamboo diagonal reinforcement results in a 9.57% reduction in the principal stress at maximum normal stress.

Grading Approaches on CIGS Material for Improved Photovoltaic Applications

Copper indium gallium selenide (CIGS) solar cell has higher absorption coefficient, long-term reliability, and low construction cost. CIGS material has a tuneable bandgap that can be adjustable. In this article, study on CIGS solar cells has been performed, and strategies were proposed for maximizing efficiency using ‘‘grading”. SCAPS-1D tool has been used for numerical simulation. CIGS solar cell performance is investigated with graded profiles i.e., linear graded, parabolic graded, parabolic-2 graded, logarithmic graded, exponential function, beta function, power law and without a graded profile (uniform pure CIGS). The results show that cells performance appears to be significantly impacted by grading. Graded power law of CIGS solar cell has delivered power conversion efficiency (PCE) of 23.2%, however the efficiency achieved by ungraded CIGS solar cells is 17.46%. The parasitic resistance has been examined via various grading simulation tools.

Methods for Motion Detection in Paper Mechanisms for Tangible Augmented Reality Interfaces

Augmented reality connects the physical world with digital environments, offering users enriched experiences for various applications, including entertainment, education, and marketing. There are proposals for tangible augmented reality interfaces, with paper mechanisms standing out due to their wide range of designs and low construction cost. These mechanisms simulate circular, lever, or linear movements along one or multiple axes, serving as tools for manipulating objects in virtual environments. This article presents prototypes of tangible interfaces based on paper mechanisms utilizing sliding tabs and incorporating elements such as ArUco markers for detecting displacement along a single axis. The tests were conducted in a controlled environment with specific lighting conditions, progressively varying the distance between the camera and the proposed mechanisms. The results highlight the advantages and disadvantages of the employed techniques, demonstrating that good motion detection accuracy can be maintained. This facilitates the direct manipulation of virtual objects for augmented reality applications.

Integrating Energy-Efficient Train Control in railway Vertical Alignment Optimization: A novel Mixed-Integer Linear Programming approach

Incorporating train control into the railway design process enables a practical and comprehensive evaluation of the lifecycle utility of a track profile. This paper proposes a novel integrated approach, termed EETC-VAO, which combines railway track Vertical Alignment Optimization (VAO) and Energy-Efficient Train Control (EETC). Initially formulated as a Mixed-Integer Nonlinear Programming (MINLP) problem, EETC-VAO aims to meet various geometric constraints and simultaneously minimize construction costs, traction energy consumption, and section running times in both directions. The model is subsequently reformulated into an equivalent Mixed-Integer Linear Programming (MILP) model using linearization methods and is further enhanced with valid inequalities, logic cuts, and a warm start algorithm with random velocity generation. The model has been extensively tested across a variety of case studies and train types, from synthetic small-scale scenarios to challenging real-world cases spanning from 3 to 71.2 km. Our findings demonstrate that operational costs can be significantly reduced with only marginal increases in construction costs. The integrated approach achieves reductions in total lifecycle costs of up to 40%, revealing a critical trade-off between construction and operational expenses. Notably, our results also indicate that lower construction costs do not inherently conflict with reduced operational costs, emphasizing the critical importance of integrating the train control scheme into the VAO problem.

The vitality of pocket parks in high-density urban areas. An evaluation system from the users' perspective in Southwest China

When concentration increases and urban land prices rise, the realization of urban parks can be difficult in new developments as well as in established areas. The scarcity of urban parks causes the decrease of residents’ accessibility to green sites, contributing to the increase of recreational and health issues. In response, pocket parks have emerged as a viable and effective solution in high-density urban conditions due to low construction costs, easy accessibility, potential widespread distribution. Although research on pocket parks is growing, very few studies propose an assessment system of pocket parks tailored to the characteristics of Chinese users. This paper explores pocket parks in high-density neighborhoods in the main cities of Southwest China and develops a system for evaluating parks' vitality from the users' perspective. The main data source are on-site observation of the activity patterns of park users, interviews on users’ experiences and perceptions of park spaces, questionnaires distributed within a representative sample of pocket parks. The research findings highlight that facilities are the elements which influence the usage of pocket parks the most, surpassing natural elements, articulation of the spaces, and location. Pocket parks, in fact, primarily provide residents with venues for daily exercise and leisure opportunities. Low-income groups are especially active participants in park’s activities. The findings allow to propose some design elements for improving the parks’ effectiveness, such as a balance between ecological benefits and functional utility.

Development and Characterization of Ammonia Removal Moving Bed Biofilms for Landfill Leachate Treatment.

Urbanization growth has intensified the challenge of managing and treating increasing amounts of municipal solid waste (MSW). Landfills are commonly utilized for MSW disposal because of their low construction and operation costs. However, this practice produces huge volumes of landfill leachate, a highly polluting liquid rich in ammoniacal nitrogen (NH3-N), organic compounds, and various heavy metals, making it difficult to treat in conventional municipal wastewater treatment plants (WWTPs). In recent years, research has shown that microbial biofilms, developed on carriers of different materials and called "moving bed biofilm reactors" (MBBRs), may offer promising solutions for bioremediation. This study explored the biofilm development and the nitrification process of moving bed biofilms (MBBs) obtained from high ammonia-selected microbial communities. Using crystal violet staining and confocal laser-scanning microscopy, we followed the biofilm formation stages correlating nitrogen removal to metagenomic analyses. Our results indicate that MBBs unveiled a 10-fold more enhanced nitrification rate than the dispersed microbial community present in the native sludge of the Porto Sant'Elpidio (Italy) WWTP. Four bacterial families, Chitinophagaceae, Comamonadaceae, Sphingomonadaceae, and Nitrosomonadaceae, accumulate in structured biofilms and significantly contribute to the high ammonium removal rate of 80% in 24 h as estimated in leachate-containing wastewaters.

Research on the Connection Technology of Assembled Monolithic Residential Wallboard

In this paper, a novel technique for connecting residential shear walls to floor slabs is investigated. Shear wall structures with two different connection methods were established and numerically analyzed using ABAQUS (2024) finite element software. The two structures were connected by sleeve grouted connections (hereinafter referred to as the original structure) and profile + bolted connections (hereinafter referred to as the new structure). Numerical analyses yielded a positive maximum load for the new structure 1.41 times that of the original structure and a negative maximum load 1.12 times that of the original structure. The ratio of the ultimate tensile strength (load value corresponding to the peak point) to the yield strength (load value corresponding to the yield point) of the two structures (strength-to-yield ratio) was in the range of 1.15–1.27. The original structure was 2.62 times more ductile in the negative direction and 2.24 times more ductile in the positive direction than the new structure. The stiffness degradation of the new structure was greater in the later stages of loading, and that of the original structure was greater in the early stages of loading. The original structure had 1.08 times the energy-consuming capacity of the new structure. The cost of labor and materials for the original structure was approximately 1.50 times the cost of the new structure. The results of the data analysis showed that, compared to the original structure, the new structure had comparable performance in terms of strength-to-flexure ratio, ductility, stiffness degradation, and energy dissipation capacity. However, the new structure was more advantageous in terms of load-bearing capacity and required lower construction costs than the original structure. Therefore, the connection nodes designed in this paper are of great significance for engineering practice.

Experimental evaluation on dynamic performance of medium–low-speed maglev vehicle running on low-positioned subgrade

ABSTRACT As a novel urban rail transit system with relatively low construction costs, medium–low-speed maglev transportation is currently experiencing rapid development in China. However, there have been rare studies on the experiments of medium–low-speed maglev vehicle passing curves and low-positioned subgrade. Therefore, this paper systematically conducts on-site dynamic tests on the Qingyuan Maglev Tourism Line. The experiment provides a detailed analysis of the dynamic characteristics of the vehicle system and subgrade under varying speeds up to 132 km/h. The study explores the impacts of operating speed, track layout, and type of girder structure. The results indicate that a significant increase in operating speed and the application of emergency braking intensify the dynamic response of the vehicle system. When passing through the R700m curve and low-positioned subgrade sections at different speeds, the primary vibration frequency of the sprung structure is below 2.5 hz, while the unsprung structure shows a wide frequency distribution. The peak frequencies of the vibration for the low-positioned subgrade are mainly distributed in the 60–140 hz range, and the vibration response of the girder remains at a low level. The Sperling index values, levitation gap, and lateral offset of the levitation electromagnet of the testing vehicle do not exceed 2.5, 4 mm, and 10 mm, respectively, indicating excellent ride comfort and stable levitation performance. The results of this test study provide a reliable assessment of the safety of the vehicle and subgrade system and would help precise modelling of vehicle and subgrade system in the future.

Scalable fabrication of flexible 3D PEDOT/rGO Scaffold for high-performance supercapacitors via a self-assembly method

Conducting polymers hold great prospects in energy storage, especially in the field of flexible energy storage, however, their broad applications are limited due to the poor processability, difficulty in structural design diversity and unsatisfactory performance when used alone. Herein, the processability of PEDOT in organic phase is significantly enhanced by surfactant modification via a self-assembly process, contributing to the convenient and low-cost construction of 3D PEDOT architecture. Importantly, the PEDOT and rGO can be introduced into the same porous structure synchronously and conveniently. Superior capacitive performance is shown for the porous PEDOT/rGO film benefits from the combination of PEDOT with excellent electrochemical stability, rGO with high conductivity and porous structure with abundant active sites and chambers for electrolyte storage. The porous PEDOT/rGO film can be used as a scaffold for the deposition of conductive polymers. For example, once PPy is deposited, a high specific capacitance of 407.8 F g-1 at a current density of 0.5 A g-1, accompanied by a prominent capacitance retention of 90% after 5000 cycles are achieved. When it is used to construct the symmetric supercapacitor (SSC), a high energy density of 52.9 Wh kg-1 at the power density of 200.2 W kg-1 is delivered, with a high capacitance retention of 85%. Moreover, it shows excellent mechanical flexibility upon multiple bending cycles, rendering great potential in portable or wearable energy storage devices.

Low cost Non freeze-drying construction strategy of cellulose aerogels for efficient solar desalination

Aerogel-like materials with three-dimensional pore structures show great potential in the field of efficient solar-driven interfacial evaporation by virtue of their fast water transport as well as efficient energy confinement properties. However, the preparation of aerogels is currently limited by high-cost strategies such as freeze drying or supercritical drying. Here, we present a foam template-assisted (FTA) strategy for atmospheric pressure drying of cellulose nanofiber (CNF) aerogels. Building a robust CNF network is the key to resisting surface tension during water evaporation and achieving drying in ambient environments, which is achieved through cleverly designed ionic cross-linking with the help of FTA. Cellulose aerogel (CA) constructed using the FTA strategy exhibit lightweight (9 mg cm−3) and porous properties (porosity: > 99 %). The tannic-coated CA (TCA) was achieved by further polymerizing tannic acid on the CA surface, which has excellent photothermal conversion capability. Meanwhile, TCA achieved an impressive evaporation rate of 3.58 kg m-2h−1 and an energy efficiency of 97.2 % at 1sun radiation by virtue of its excellent energy confinement and water management capabilities. This strategy provides a promising solution for the low-cost construction of aerogels as well as for the realization of efficient solar-driven interfacial evaporators.

Experimental investigation on wind loads and wind-induced responses of large-span flexible photovoltaic support structure

Flexible photovoltaic (PV) support structure offers benefits such as low construction costs, large span length, high clearance, and high adaptability to complex terrains. However, due to the high flexibility and low damping of the cable system, wind load becomes the primary control factor for structural safety and the key consideration in the design. In this study, a 45 m span flexible PV support structure with 3 spans and 12 rows was designed. The wind loads on PV panels were obtained by wind tunnel tests on a rigid model and the wind-induced responses were investigated by wind tunnel tests on an aeroelastic model. The shielding effects and tilt angle of PV modules on the wind load and wind-induced vibration of the flexible PV support were studied. The experimental results show that in the rigid model wind tunnel test, the wind pressure on the surface of PV modules exhibits a gradient distribution along the direction of wind flow, with symmetric distribution along the mid span. With the increase in the tilt angle of the PV module, the shielding effect becomes significant and the most pronounced shielding effect on the mean wind pressure coefficient occurs in the second row of the windward zone. In aeroelastic model wind tunnel tests, the mean vertical displacement of the flexible PV support structure increases with the increase of wind speed and tilt angle of PV modules. Due to the wind-resistant anchor cables set in both the windward and leeward zones, the vibration amplitude near the edge rows is significantly smaller than that of the middle rows when the structure is subjected to wind suction. When the flexible PV support structure is subjected to wind pressure, the maximum mean vertical displacement occurs in the first rows at high wind speeds. The shielding effect has a noticeable impact on the wind-induced response of the leeward zone at α = 20° under wind pressure, resulting in the decrease of amplitude vibration by approximately 53 %. The wind vibration coefficients in different zones under the wind pressure or wind suction are mostly between 2.0 and 2.15. Compared with the experimental results, the current Chinese national standards are relatively conservative in the equivalent static wind loads of flexible PV support structure.

Рекомендації з відновлення водопропускальних труб із застосуванням металевих гофрованих конструкцій

Introduction. The reliability and durability of culverts are affected by static and dynamic loads from vehicles and temperature and climatic influences, the destructive force of water flow, abrasive destruction, corrosion of the material, shortcomings in the choice of structures and unsatisfactory design, all of which cause the premature collapse of the structure. Today, culverts made of metal corrugated structures (hereinafter referred to as metal corrugated structures) are widely used. The well-known advantages that justify the choice of such a solution are mainly a short term and a relatively low cost of construction, construction provided that the appropriate technological regime is observed does not cause any particular problems. Therefore, there is a need to develop a recommendation for the restoration of culverts using metal corrugated structures. Problems. It was established that there is a need to restore culverts without stopping the movement of vehicles. Goal. It consists in offering approaches for the restoration of culverts using metal corrugated structures.

Oxidation and ablation resistance of (TiZrHf)C medium-entropy ceramic coating on C/C composite constructed in-situ at low temperature down to 900°C

The low-cost construction of ultra-high temperature high/medium-entropy ceramic coatings is pivotal for advancing their engineering applications. The study successfully prepared (TiZrHf)C medium-entropy ceramic coatings on C/C composite surfaces using an in-situ molten salt disproportionation reaction at temperatures as low as 900°C. The (TiZrHf)C coatings, approximately 20 μm thick, showed uniform distribution of Ti, Zr, and Hf, typical of medium-entropy ceramics. The process entails Hf reducing Zr⁴⁺ and Ti⁴⁺ to divalent states, which then disproportionate and react with carbon to form the coatings. High-temperature oxidation tests revealed larger oxide grain sizes and dense boundaries in coatings with higher Ti content, indicating superior oxidation resistance. Additionally, ablation tests demonstrated that a suitable amount of liquid-phase TiO₂ formed on the composite surface improves ablation resistance by stabilizing the oxide layer. This cost-effective, highly designable method promotes medium/high-entropy ultra-high temperature ceramics' engineering application.

Experimental void fraction measurement approach of small channel two-phase flow

This investigation presents a novel experimental approach for assessing void fraction parameters in two-phase flows within microchannels. The study critiques the conventional impedance methods that utilize alternating current (AC) for void fraction measurements, highlighting the inherent drawbacks such as ground capacitance interference and non-uniform current distribution. To circumvent these issues, the research introduces the use of direct current (DC), which ensures a homogeneous distribution across the conductor's cross-section, as a more reliable alternative. Termed the "Direct Impedance Method," this technique employs DC to enhance the accuracy of void fraction measurements. The study explores various geometric configurations of full-ring and half-ring electrodes, both vertical and horizontal, within a microchannel of 500 μm diameter. An empirical formula is derived to calculate the void fraction from the electrical data obtained. High-speed imaging at 4000 frames per second supplements the method by providing visual confirmation of the flow patterns. The comparative analysis of the direct impedance method and image processing using the homogeneous theoretical model reveals a deviation of approximately 2 %–10 % for the slug and annular flow pattern. In contrast, the deviation is more for the bubble pattern. The results affirm that the Direct Impedance Method is a cost-effective and reasonably precise technique for small-channel applications. Its accuracy is inversely proportional to the channel diameter, rendering it unsuitable for channels larger than 2 mm. The method's low construction cost further enhances its practical appeal.

Experimental Research on Dynamic Mechanical Properties of High-Density Foamed Concrete.

Foamed concrete is increasingly utilized in protection engineering because it offers a high energy absorption ratio and a relatively low construction cost. To investigate the dynamic properties of foamed concrete, a series of dynamic compression tests are carried out on high-density foamed concrete with densities of 800 kg/m3, 1000 kg/m3, and 1100 kg/m3 under a strain rate range of 59.05 s-1~302.17 s-1 by using a Φ-100 mm split Hopkinson pressure bar (SHPB) device. The effects of strain rate on the stress-strain relationship, dynamic compressive strength, and dynamic increase factor of foamed concrete are discussed in detail. The results show that the dynamic mechanical characteristics of foamed concrete with different densities exhibit a significant strain rate enhancement effect. Additionally, the energy absorption characteristics of foamed concrete are investigated, demonstrating that it can effectively prevent the transmission of incident energy and that its energy absorption efficiency declines as the strain rate increases. A high-speed camera was also employed to capture the failure process of foamed concrete. The results exhibit that fracture production and development induce the failure of foamed concrete, the failure process of foamed concrete advances as the strain rate increases, and the failure mode becomes increasingly severe.

A box quadrat for standardised sampling of Orthoptera in open habitats: Design, handling, applications and baseline data

Globally, insects are declining at an alarming rate. Therefore, there is an urgent need for standardised monitoring methods to detect changes in insect populations at an early stage. Box quadrat sampling enables highly precise assessments of Orthoptera community composition within a specific area. However, a detailed design of a box quadrat that guarantees an easy workflow, precise descriptions of its handling and a compilation of baseline data for future comparisons have yet been lacking. Based on thirty years of our own experience in box quadrat sampling, we present here: (i) the detailed design of a box quadrat, (ii) its standardised handling in the field (including a video as a supplement), (iii) its applications and (iv) Orthoptera species richness and abundance baseline data for open habitats. The low construction costs (∼300 €) and simple design allow for a wide distribution of this type of box quadrat in future. Moreover, due to the plug system and the light aluminium construction, the quadrat can easily be transported, assembled, handled and dismantled by one person. For comparisons of Orthoptera species richness, abundance and community composition between habitats, we recommend using a quadrat of 2 m² size and 0.8 m height and a minimum sampling area of 20 m² per plot (10 touchdowns per plot). For long-term monitoring or when species are sampled that generally occur in low density, a sampling area of 30 m² (15 replicates) is suggested. By contrast, for the surveys of tiny species (e.g., groundhoppers) and developmental stages (nymphs), smaller box quadrats can also be used and the sampled area per plot can be below 20 m². Box quadrat sampling is less dependent on favourable weather conditions and vegetation structure than many other insect survey techniques. Overall, it allows rapid and highly precise assessments of Orthoptera community composition.