JOURNAL OF MATERIALS & CONSTRUCTION

Evaluation of the longitudinal reduction in reinforcing steel diameter due to corrosion in experimental reinforced concrete beams using a statistical model

Nguyen Thanh Hung — 2026-04-08

Corrosion of steel reinforcement is one of the main issue of reduced load-bearing capacity and durability of reinforced concrete structures. In this study, the degree of reduction in steel reinforcement diameter due to corrosion was evaluated by accelerated corrosion testing on reinforced concrete beams labeled D21, D22, D23, and D24. After the corrosion process was complete, the steel bars were removed, the corrosion products were cleaned, and the remaining diameter was measured at various locations along the length of the steel bars. The data were processed using statistical methods, frequency plots were constructed, and normal distribution analysis was performed to evaluate the characteristics of the reduction in diameter of Φ12 and Φ16 steel bars in the beams. The results showed that the reduction in steel reinforcement diameter was uneven along the longitudinal direction of the beams, with Φ16 steel bars exhibiting a higher average reduction value and greater dispersion compared to Φ12 steel bars. The research results provide important experimental data for evaluating the degree of corrosion and remaining load-bearing capacity of corroded reinforced concrete beams.

The importance of teaching English for Specific Purposes in architecture and construction in Hanoi Architectural University

Chu Anh Dat — 2026-02-06

This paper discusses the importance of teaching English for Specific Purposes (ESP) in the fields of architecture and construction in HAU (Hanoi Architectural University), where effective communication and access to updated knowledge are crucial for academic and professional success. As globalization reshapes the construction industry, English has become the lingua franca for international collaboration, technical documentation, and design innovation. The study highlights how ESP contributes to students’ academic performance by improving their reading comprehension of technical texts, writing skills for project documentation, and presentation abilities in design studios. Moreover, it emphasizes the professional advantages of ESP, such as negotiating contracts, preparing tenders, and networking in international forums. The paper also examines the role of ESP in facilitating access to global research, technology, and sustainable practices, which are often published in English. Challenges in teaching ESP in HAU including limited resources, lack of subject-specific expertise among teachers, and varying student motivation—are also solved. Finally, the article suggests strategies such as needs analysis, collaboration with subject experts, and task-based learning to enhance ESP instruction. Overall, the paper argues that integrating ESP into architecture and construction education is vital for preparing future professionals to thrive in an increasingly interconnected and competitive global environment.

Design guide for ferrocement floating pontoons for flood-adapted housing in the Mekong Delta

Do Thi My Dung — 2026-02-20

Climate change, sea-level rise, and increasingly severe floods have intensified the demand for flood-adapted housing solutions in the Mekong Delta. Ferrocement floating pontoons are a promising option because they can be locally fabricated, provide adequate structural performance for thin-walled water-retaining tanks, and enable multifunctional use (e.g., flotation during floods and water storage in dry seasons). This study develops a practical calculation and design guide for ferrocement floating pontoons serving as buoyant foundations for floating/amphibious houses. The guide defines representative pontoon cross-sections (rectangular and U-shaped) and preliminary buoyancy sizing based on floor-area loading, equilibrium flotation, and freeboard requirements; formulates actions and load combinations consistent with pontoon working stages, including: pontoons resting on the ground subjected to external hydrostatic pressure and ground reaction, initial flotation under buoyancy, lateral water pressure and wave effects, and special accidental conditions including impact; and provides structural checks for strength and serviceability, emphasizing crack-width control for durability in non-aggressive and aggressive/water-retaining environments. For house systems guided by four corner posts or restrained by four flexible mooring lines, the guide highlights controlled vertical movement and connection detailing to prevent pontoon separation. The proposed workflow supports safer, more consistent engineering design and local deployment of ferrocement pontoons for flood resilience in the Mekong Delta.

Effect of the concrete compressive strength on the structural behaviour of the steel concrete composite cloumn

Le Van Phuoc Nhan — 2026-02-06

Composite column has been popularly used in buildings, which are mainly subjected to forces and end moments. There are two types of the steel concrete composite columns: open sections partially or fully encased in concrete, and concrete-filled hollow steel sections. The first type of section has used for fireproof and the slender structural steel can be protected buckling by the exterior concrete, while the remaining type can prevent the transverse deformation of the concrete inside and enhance the load capacity. The steel tube serves as a formwork for casting the concrete, which reduces the construction cost. In this study, four the steel concrete composite columns with concrete-filled hollow steel sections were tested to investigate the effect of the concrete compressive strength on the structural behaviour of the steel concrete composite columns. The parameters observed are load capacity, longitudinal and transverse deformation of the tube steel and the concrete, and the column failure.

A comprehensive comparison between traditional project management and BIM-based management: Evidence from the Vietinbank tower project

Ta Van Phan — 2026-04-06

The construction industry is shifting from traditional 2D-based management to Building Information Modeling (BIM) to handle the increasing complexity of high-rise buildings. This paper provides a rigorous comparison between traditional Project Management (PM) and BIM-integrated PM. By utilizing the Vietinbank Tower - a "Special Grade" project in Hanoi - as a case study, the research demonstrates how BIM resolves deep-seated issues in coordination, quantity takeoff, and scheduling. The findings suggest that while BIM requires higher initial investment, it significantly reduces risks and improves structural quality through Level of Development (LOD) 400 modeling and automated clash detection.

Quantification of accuracy degradation in differential leveling under unfavorable terrain conditions

Le Khanh Giang — 2026-03-26

Differential leveling is a fundamental surveying technique valued for its simplicity and high intrinsic precision. The method’s accuracy relies on the midpoint principle, wherein the level instrument is placed equidistant between backsight and foresight staffs to eliminate distance-dependent systematic errors. However, in mountainous or complex terrains, this ideal configuration is often impractical. The instrument must then be set at a perpendicular offset from the baseline, which increases sight distances and error propagation. This study investigates the mechanisms of accuracy degradation under such unfavorable conditions, focusing on the geometric elongation of the optical sight path. We analytically examine the principal distance-dependent error sources, including collimation error, vertical index error, Earth curvature, atmospheric refraction, and staff-reading uncertainty, and show how they scale with sight length. Using the geometric relationship between the ideal baseline and actual sight lengths, we derive an accuracy degradation coefficient K to quantify the loss of efficiency caused by offset instrument placement. The coefficient is evaluated over a range of offset ratios (0.05 ≤ h/S ≤ 2.00), revealing a pronounced non-linear decrease in accuracy with increasing offset. The results indicate that degradation remains minor for h/S < 0.25, becomes significant for moderate offsets (0.25 < h/S < 0.9), and is severe when h/S > 1.5. Based on these findings, we propose practical guidelines: applying double-station leveling in moderate-offset conditions and resorting to alternative height-determination methods in extreme terrain. The proposed degradation coefficient provides a simple tool for survey planning and quality control, enabling engineers to assess expected accuracy loss and design appropriate observation strategies for differential leveling in challenging topographic environments.

Compressive strength of cement mortar incorporating graphene-based nanosheets in powder and liquid forms

Bui Quoc Bao — 2026-04-02

This study investigates the influence of graphene-based nanosheets (GNS) in both liquid (G-L) and powder (G-P) forms on the compressive strength development of cementitious composites. Mortar specimens were prepared with GNS concentrations ranging from 0% to 1% by weight of cement and tested at 1, 3, 7, and 28 days. The results indicate that G-P consistently enhanced compressive strength, with the optimal dosage (0.3-0.5%) improving 1-day strength by up to 24%, and 28-day strength by 17%. Conversely, G-L exhibited inconsistent early-age performance, with some dosages causing strength reductions (e.g., 0.3% G-L decreased 3-day strength by 7%), although higher concentrations (0.8-1.0%) improved 28-day strength by up to 14%. Excessive graphene content (≥0.8%) led to agglomeration, negatively impacting early-age strength despite long-term improvements. These findings provide valuable insights into the optimization of GNS dosage to enhance the performance of cement-based materials, or for the reduction of cement without change the mechanical strengths.

Influence of curing methods on the compressive strength development of 3D-printed concrete unit cells

Pham Thi Loan — 2026-03-27

This study provides a direct, quantitative comparison of three practical curing methods—Natural air-drying (ND), Membrane sealing (MB), and Water Immersion (WI)—on the compressive strength development of 3D-printed concrete (3DPC). Unit cell specimens were fabricated and subjected to the curing regimes immediately after printing, with strength evaluated at 7 and 28 days. Results demonstrate a substantial influence of the curing method. Membrane sealing (MB) proved most effective, yielding the highest strength (16.7 MPa and 19.7 MPa at 7 and 28 days, respectively). Using MB as a baseline (100%), a Relative Performance Index (RPI) revealed that Immersion (WI) and Natural curing (ND) retained only 89% and 80% of the 28-day strength, respectively. Qualitative analysis of failure modes showed cohesive vertical cracking without interlayer delamination, indicating that interlayer bonds remained competent and that the strength reduction under poor curing is primarily due to a generalized weakening of the cementitious matrix. This finding underscores that effective curing enhances overall material homogeneity. The pronounced performance deficit, particularly under natural drying, directly quantifies the critical vulnerability of 3DPC's layered microstructure to moisture loss. The findings deliver clear, data-driven evidence for implementing impermeable membrane curing as a vital and practical site practice to ensure the mechanical performance of digitally fabricated concrete.

Kinetic equation of aerobic granular sludge cultivation in a Sequencing Batch Reactor (SBR) treating municipal wastewater in Vietnam

Pham Van Doanh — 2026-03-26

During the formation of aerobic granular sludge in wastewater treatment systems, numerous factors influence the granulation time, granule size, and structural stability of the sludge. The kinetics of granule formation are associated with the increase in granule size over the cultivation period. Kinetic-related factors include the influent organic loading rate, aeration intensity, and the nitrogen-to-COD (N/COD) ratio.In this study, the kinetic equation and the kinetic profile of aerobic granular sludge cultivation using Sequencing Batch Reactor (SBR) technology for domestic wastewater treatment under laboratory conditions in Vietnam are presented. The research was conducted using a laboratory-scale SBR model with a reactor diameter of 0.110 m, a height of 1 m, and a working volume of 2.5 L. Each operational cycle lasted 4 hours and consisted of four phases: a feeding phase of 1–2 minutes, an aeration phase of 180 minutes, a settling phase of 20–30 minutes, and a discharge phase of 10–15 minutes. The influent wastewater with an organic loading rate ranging from 2.7 to 3.0 kg COD/m³·day. The total experimental duration was 140 days. The results indicated that the kinetic model could successfully predict the formation and development of aerobic granular sludge with a reliability coefficient of 0.985 (R² ≈ 0.98).

Experimental study on the influence of non-fired brick walls on the behavior of multi-span reinforced concrete frames

Lam Thanh Quang Khai — 2026-02-06

In construction projects, the infill wall within the frame primarily serves the purpose of providing coverage. Nonetheless, this infill wall also plays a role in enhancing the stiffness of the frame, thereby minimizing the horizontal displacement of the structure. Infill walls are commonly constructed using fired clay bricks. However, in recent years, the extraction of clay for brick production has led to the depletion of clay resources and has had a significant negative impact on the environment. This study involved the use of non-fired brick to create infill walls within two-span reinforced concrete frames. The research findings indicate that the bearing capacity of the frame improved by 220% when utilizing non-fired brick measuring 40×80×180mm and 80×80×180mm. Utilizing 40×80×180mm non-fired brick results in an 8.4 times reduction in the horizontal displacement of the frame. In contrast, employing 80×80×180mm non-fired brick leads to an 8.9 times reduction in horizontal displacement, both measured against the case without brick filling at a load level of 50kN, which represents the destructive load level of the frame absent infill walls.

Modified space-truss model for predicting the torsional capacity of ultra-high-performance concrete beams

Nguyen Vu Luat — 2026-02-13

Ultra-high-performance concrete (UHPC) beams exhibit enhanced post-cracking stress transfer due to fiber bridging, a mechanism not adequately represented in conventional torsion design provisions. This study develops a modified space-truss model (MSTM) to predict the ultimate torsional capacity of UHPC beams under pure torsion. The proposed formulation retains the three-dimensional space-truss analogy and thin-walled tube idealization, while explicitly incorporating the tensile contribution of UHPC through equivalent longitudinal and transverse tensile components. In addition, the inclination angle of the concrete strut is refined using equilibrium and strain-compatibility considerations rather than fixed code-recommended values. The reliability of the MSTM is validated using a compiled database of 40 UHPC beams from previous experimental studies and benchmarked against the truss-based provisions in ACI 318-19 and GB 50010. The results indicate that both code-based approaches tend to provide conservative predictions. In contrast, the proposed MSTM achieves improved agreement with experiments (mean value = 0.90 for T_u,cal/T_u,exp) while remaining slightly conservative for design.

AI-Based prediction of fine-aggregate geopolymer concrete strength using machine learning algorithms

Le Thanh Ha — 2026-03-17

This study presents a machine learning framework implemented in WEKA to predict the compressive and flexural strengths of fine-aggregate geopolymer concrete (FAGPC). Utilizing two experimental datasets (90 instances for compressive strength and 45 instances for flexural strength), the study investigated the non-linear relationships between fly ash/ ground granulated blast-furnace slag contents, curing age and strength. Four classical regression algorithms—M5P, REP Tree, Random Forest and Random Tree —were systematically evaluated using an 80/20 train-test split. Model performance was evaluated by using several statistical performance indicators, including the Correlation Coefficient (R), mean absolute error (MAE), relative absolute error (RAE), mean squared error (MSE), and root mean squared error (RMSE). The results demonstrate reliable predictive performance for both mechanical properties. For compressive strength, the Random Tree model achieved the highest correlation (R = 0.7628), while the REP Tree model yielded the lowest error (RMSE = 7.02 MPa) on the test set. For flexural strength, the Random Forest model emerged as the superior predictor, achieving an outstanding correlation coefficient (R = 0.8833) and a low RMSE of 1.00 MPa. These findings indicate that the selected input variables (precursor content, curing age) are sufficient to capture the complex behavior of FAGPC.

Proposed model for evaluating strategies for sustainable social housing development in Vietnam

Vu Phuong Ngan — 2026-04-09

Sustainable social housing development is a complex systemic challenge that requires a balanced integration of the economic, social, and environmental pillars, while also being shaped by the interdependent and dynamic relationships among various strategies and influencing factors. In such a context, conventional ranking methods are inadequate, as they fail to capture the feedback loops, interactions, and causal structures inherent in the system. Therefore, a more comprehensive and integrated analytical approach is necessary. This study proposes a hybrid evaluation framework combining the Analytic Network Process (ANP), Decision-Making Trial and Evaluation Laboratory (DEMATEL), and Interpretive Structural Modeling (ISM) integrated with MICMAC analysis. The ANP method is first applied to determine the relative priorities and weights of strategies within a network structure that reflects interdependencies. DEMATEL is then used to identify and analyze cause–effect relationships among factors, thereby clarifying the direction and strength of influence. Based on these results, ISM is employed to construct a hierarchical model of strategies, while MICMAC further classifies them according to their driving power and dependence. The proposed framework provides a robust scientific basis for decision-making and supports the formulation of effective strategies for sustainable social housing development, with potential applicability to other complex multi-criteria system.

Partial replacement of natural sand with recycled waste oyster shells in concrete production of grade 30 MPA

Ho Viet Thang — 2026-04-06

In the construction industry, concrete is a vital material, and natural sand is an essential aggregate component. However, natural sand resources are currently becoming increasingly scarce due to excessive exploitation. Furthermore, oyster shells, a waste product from aquaculture and seafood processing, are difficult to decompose and contribute to environmental pollution. Consequently, investigating the utilization of finely crushed waste oyster shells to partially substitute natural sand in concrete production represents a promising and necessary approach, simultaneously mitigating pollution and effectively utilizing available waste streams. In the present study, oyster shells were finely ground and used to replace natural sand at substitution ratios ranging from 5% to 20%. The results, based on measurements of slump, compressive strength, and water absorption of the concrete, conducted in accordance with Vietnamese standards, indicate that the crushed shell is capable of replacing up to 15% of the natural sand while maintaining the requisite properties and technical specifications of the concrete.

Assessing the Impact of Air Pollutant Dispersion from the manufacture at Van Dien Fused Magnesium Phosphate Fertilizer Joint Stock Company on the Roadmap for Establishing Low Emission Zones in Hanoi

Nguyen Thu Huyen — 2026-04-06

This paper investigated and evaluated the dispersion of air pollutants generated from the ore pyrolysis process at the Van Dien Fused Magnesium Phosphate Fertilizer Joint Stock Company. It also analyzed technical conflicts regarding the roadmap for establishing a Low Emission Zones (LEZs) in Southern Hanoi. Based on multi-temporal modeling data from Quarter 3/2023 to Quarter 2/2024, the study identified the concentration ranges of Total Suspended Particulates (TSP), Nitrogen Oxides (NO_x), Hydrogen Fluoride (HF), and Sulfur Dioxide (SO₂) in urban spaces. The results showed that NO_x concentrations in the core emission area approached the maximum permissible limits of QCVN 05:2023/BTNMT, creating a significant burden on the background environment. Analysis of dispersion maps presented that in the weather conditions during Quarter 1, pollution plumes containing HF and SO₂tended to migrate deep into the boundaries of the former Ha Dong District and Thanh Oai District. These are key areas designated for implementation of LEZs under Resolution 57/2025/NQ-HDND. The study asserted that the presence of point emission sources operating near permissible limits at the capital's gateway directly contradicted the clean air objectives of the Low Emission Zones (LEZs). Consequently, this paper proposed urgent measures based on Directive 19/CT-UBND (2025), encompassing dynamic manufacturing curtailment mechanisms and strategic relocation roadmaps to alleviate environmental pressure, thereby fostering a sustainable urban ecosystem.

Can blockchain replace auditors?

Nguyen Thu Huong — 2026-02-26

Blockchain technology is a modern application of the 4.0 industrial revolution, applied in many fields; auditing is not exempt from its influence. Blockchain is a general ledger that records all transactions of parties participating in the system. With Blockchain, double-entry has been moved to a completely new era - Triple-entry. All parties can view and check information on the Blocks. With automatic recording and checking of transactions, Blockchain will reduce a large amount of work for accountants. At the same time, with the advantage of high accuracy, the difficulty in falsifying information will significantly reduce the sample size in the detailed testing of auditors. The article summarizes the development process and operation of Blockchain in general and Blockchain for accounting records, studies the transformation of accounting from single entry to double entry, and develops into Triple entry under Blockchain technology conditions. From there, the article analyzes and evaluates the impacts and challenges on auditing work.

Utilizing solar power to improve the efficiency of road lighting systems

Vu Phuong Thao — 2026-04-06

The road lighting system is an important technical infrastructure that ensures safety and security. However, using traditional light sources such as High-Pressure Sodium (HPS) lamps has revealed several limitations in terms of energy efficiency, operational costs, and greenhouse gas emissions, thereby impacting on the environment. This paper focuses on the application of solar-powered LED lighting systems (PV-LED) as a sustainable and efficient alternative for both urban areas and remote regions without access to the electrical grid. The study shows that over a 5-year lifecycle, a 50W PV-LED system can save more than 600 kWh of electricity compared to grid-powered 50W LED lighting. Moreover, PV-LED systems substantially cut greenhouse gas emissions, with total lifecycle emissions reduced by approximately 45% compared to conventional grid-powered LED lighting. Obviously, PV-LED lighting offers both economic and environmental benefits, contributing to the development of sustainable cities.

Evaluation of the strength, dimensional stability, and microstructure of lightweight alkali-activated mortar incorporating used coffee grounds

Nguyen Van Dung — 2026-02-27

Due to the shortage of natural river sand and the uncontrolled disposal of coffee waste, this study investigates the use of used coffee grounds (UCG) as a partial replacement for fine aggregate in producing lightweight alkali-activated mortar (LAAM). Coal bottom ash (BA) was replaced with UCG at 0%, 5%, 10%, and 15% by volume. Experimental evaluations included segregation resistance, compressive strength, ultrasonic pulse velocity (UPV), drying shrinkage, and microstructural analysis. The results showed that all mixtures exhibited acceptable homogeneity without significant segregation. A 5% UCG replacement increased compressive strength and UPV compared with the control mixture, owing to improved matrix compactness and internal curing. However, higher UCG contents led to reduced compressive strength and UPV values. Drying shrinkage decreased in UCG-modified mixtures, with LC-15 exhibiting the lowest shrinkage (best dimensional stability). SEM observations confirmed denser gel formation and better particle matrix bonding in LC-05, whereas LC-10 and LC-15 showed weaker interfaces and more voids. A 5% UCG content is recommended for practical application. These findings highlight the potential of UCG as an environmentally friendly alternative to fine aggregate for lightweight composites, supporting waste valorization and reducing the consumption of natural sand.