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2007 research outputs found
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Application of Feldspar Sand in Non-Autoclaved Foam Concrete Technology
No full textThe aim of this study is to determine the possibility of producing non-autoclaved foam concrete of grade M35 with a density of 900 kg/m³. A distinctive feature of this development is the testing of twin samples from the same batch: some were steamed in a chamber at 90 °C under normal atmospheric pressure, while others were autoclaved at a pressure of 8 bar and a temperature of 170 °C. It was established that ordinary natural feldspar sands with a fineness modulus ranging from 1.43 to 2.45, containing quartz below the standard-regulated levels, can be used in the production of non-autoclaved foam concrete. It is not possible to obtain non-autoclaved D900 foam concrete of grade M35 strength using only cement, sand, and foaming agent. To achieve the specified strength, it is necessary to use coarse sand with a fineness modulus (FM) greater than 3, subjected to short-term grinding to reduce the FM to recommended values, and to additionally introduce sol-gel liquid glass. The novelty lies in the experimental confirmation of the features of strength formation in cellular concrete under both non-autoclaved and autoclaved curing conditions. Comparative tests showed that high strength in cellular concrete is achieved only when a chemical bond forms between the products of cement hydrolysis and hydration with quartz sand grains—conditions made possible through autoclaving
Geopolymer Mortars from Tuff Waste: A Circular Approach
No full textThis study explores the potential use of volcanic tuff mining waste in geopolymer mortar formulations, aiming to enhance recycling and promote sustainable construction. Two filler-to-binder ratios (70/30 and 65/35) were developed using a geopolymer binder composed of tuff waste, dolomite powder, and sodium silicate. The mortars were subjected to heat treatments at 200, 350, 500, and 650°C for 8.5 hours. Compared to natural tuff (reference sample), water absorption decreased from 16.8% to 7.7%, with the lowest absorption observed in the 65/35 composition. Flexural strengths increased by 0.97% to 117.1%, and compressive strengths improved by 17.8% to 97.1%, reaching their maximum at 500°C; at 650°C, strengths declined due to water evaporation, shrinkage, and microcrack formation. Softening coefficients increased by over 10%, indicating enhanced resistance to water-induced softening. The study demonstrates that incorporating dolomite powder improves water resistance, while tuff waste serves effectively as both filler and binder component. Moreover, geopolymer mortars produce significantly lower CO₂ emissions (0.133 t/m³) compared to ordinary Portland cement mortars (0.415 t/m³), highlighting their environmental advantage. These results underscore the potential of tuff-based geopolymer mortars for sustainable construction applications
Methodology for Seismic Vulnerability Assessment of Pre-Code Masonry Buildings Using Region-Specific Data
No full textThis study presents a comprehensive methodology for evaluating the seismic vulnerability of existing pre-code masonry structures through a multidisciplinary approach that integrates region-specific building typologies with site-specific seismic input. A key gap motivating this work is the absence of fragility curves for masonry structures typical of the region despite their prevalence and high seismic exposure. Recognizing the importance of reliable Seismic Hazard Assessment (SHA) in risk evaluation, a scenario-based Neo-Deterministic Seismic Hazard Assessment (NDSHA) approach was employed. This method incorporates a detailed understanding of the region’s tectonic regime, active fault systems, earth crust structure, and historical seismicity to produce realistic site-specific response spectra for analysis. The seismic capacity of the structures was assessed using multiple iterations of a nonlinear static (pushover) analysis, accounting for uncertainties in the material and geometric input parameters. The structural displacement was used as the primary damage index, and the damage was classified into five discrete damage grades. Consequently, new fragility and reliability curves were developed: (i) a general set for unreinforced masonry (URM) structures, (ii) four regional sets corresponding to distinct zones within the country, and (iii) two sets differentiating between regular and irregular plan configurations. The novelty of this study lies in the development of region-specific fragility curves for URM buildings, providing urgently needed tools for seismic risk assessment and supporting mitigation strategies and decision-making at the local and national levels
Finite Element Analysis of Concrete Beams Reinforced with Basalt Fiber-Reinforced Polymer
No full textThe increasing demand for corrosion-resistant reinforcement in concrete structures has highlighted the potential of basalt fiber-reinforced polymer (BFRP) bars as a sustainable alternative to conventional steel reinforcement. However, the flexural behavior of BFRP-reinforced concrete beams remains insufficiently characterized, particularly through advanced numerical simulation. This study develops and validates a finite element model (FEM) to analyze the flexural performance of BFRP-reinforced concrete beams and to compare it with that of steel-reinforced beams. Eight beam specimens (200 × 300 × 3,100 mm), including six reinforced with BFRP bars and two with steel bars, were modeled under four-point bending using ANSYS software. The FEM predictions were validated against experimental data and benchmarked with the design provisions of ACI 440.1R-15 and CSA S806-12. The model showed strong agreement with experimental results, yielding ultimate load ratios of 0.92–0.94 for steel-reinforced beams and 1.01–1.45 for BFRP-reinforced beams. At higher reinforcement ratios, FEM predictions tended to overestimate the capacity of BFRP-reinforced beams. While steel-reinforced beams exhibited ductile failure, BFRP-reinforced beams failed in a brittle manner. The predicted moment-deflection responses and crack patterns closely matched both experimental observations and code-based predictions. This validated FEM provides a reliable computational framework for assessing and optimizing the design of BFRP-reinforced concrete beams, thereby advancing the application of non-metallic reinforcement in structural engineering. The findings also highlight challenges in accurately modeling concrete crushing and bond behavior within FEM, indicating directions for future refinement
Experimental Study on Electrochemical Corrosion Law of Rebar Under Alternating Magnetic Field
No full textThe alternating magnetic field (MF) environment of coastal substations and magnetic levitation systems generates strong electromagnetic interference, which may affect the corrosion behavior of rebars in concrete structures. To clarify the influence law of rebar corrosion when exposed to an alternating MF, an alternating MF simulation test device was designed and manufactured according to the principle of alternating electromagnetic induction. The macroscopic corrosion morphology and electrochemical corrosion characteristics of rebars under alternating MF of different intensities were investigated by accelerated corrosion tests, electrochemical tests and natural corrosion electrochemical tests. The corrosion behavior mechanism of rebars under alternating MF was revealed. The results show that: 1) The diffusion rate and concentration of corrosion products in the solution are proportional to the magnetic induction strength. The alternating MF accelerates rebar corrosion. 2) The Ecorr of rebar shifts negatively with the magnetic induction strength increases, with a more pronounced shift in the early stage of corrosion than in the later stage. 3) Under the natural corrosion state, the 5 mT MF makes the open circuit potential (OCP) shift 12 mV negatively compared with that without MF. When the potential reaches 8mV, the passivation film begins to be destroyed. 4) The R1 of rebar is inversely proportional to the magnetic induction strength
A Semantic-Enabled Common Data Environment for Real-Time Digital Twin Applications in Small-Scale Construction Projects
No full textThe integration of Building Information Modeling (BIM) and Digital Twin (DT) systems has reshaped construction project delivery, but their application remains concentrated in large, resource-intensive developments. Small-scale projects, which dominate the built environment in many regions, often lack access to advanced digital platforms due to financial constraints, insufficient infrastructure, and limited technical capacity. Existing Common Data Environment (CDE) frameworks are typically monolithic and costly, making them unsuitable for the flexible and affordable deployment needed in these contexts. A persistent barrier is semantic fragmentation: without interoperable data exchange across BIM, Internet of Things (IoT) devices, and Geographic Information Systems (GIS), project information remains siloed and underutilized. This study introduces a modular, semantic-enabled CDE architecture designed specifically for small-scale projects. The framework incorporates lightweight ontologies, microservices, and knowledge graphs to deliver scalable and semantically coherent integration of BIM–IoT–GIS datasets. To validate its applicability, the research applies the model to a three-storey educational building, demonstrating how real-time DT functionality can be achieved with minimal infrastructure demands. The case study highlights improvements in data exchange, operational monitoring, and sustainability analysis, showing how the architecture supports predictive maintenance and decision-making. By synthesizing insights from literature and practical demonstration, the paper proposes a blueprint for democratizing DT adoption, enabling affordable, adaptable, and interoperable solutions for small-scale construction projects
Experimental and Numerical Study of Enlarged-Head Monopile Under Lateral Load in Soft Clay
No full textThe behavior of piles and the reaction of soils in contact with structures are crucial aspects of foundation engineering. Laboratory model tests were investigated to evaluate the enhancement of the subgrade modulus for laterally loaded piles with enlarged heads in clay. These tests compared typical piles with enlarged heads in soft clay, considering factors such as the pile slenderness ratio and geometric configurations. The study was expanded by simulating monopiles with and without head enlargements using the numerical program Plaxis 3D. The results highlight the effectiveness of enlarged-head piles, demonstrating a substantial increase in lateral subgrade reaction with adequate head depth. For piles with Lp/Dp = 24, an enlarged head geometry of Le/Lp = 0.4, Δ De/Dp = 1, and an undrained shear strength Cu = 15, the subgrade modulus improved by 200% compared to typical piles. Additionally, for Lp/Dp = 24 piles, the improvement due to enlargement was 1.3 and 2 times for Cu values of 10 and 15 kPa, respectively. These findings emphasize the advantages of using enlarged heads, especially uniform shapes, which are more practical and effective than tapered shapes. The numerical simulations corroborated the experimental results, providing detailed insights into deformation and bending moment variations that are challenging to measure in laboratory tests. Doi: 10.28991/CEJ-2025-011-02-04 Full Text: PD
River Sand Replacement with Sustainable Sand in Design Mix Concrete for the Construction Industry
No full textThe present study prepared four sustainable design mixes of concrete using desert sand, modified recycled sand, and supplementary cementitious material silica fume to replace cement. The design mix concrete was prepared using the absolute volume method of a design strength (f´c) and target strength (f´cr)of 30 MPa and 38 MPa, respectively. The analysis of results showed that the four sustainable design mix concrete successfully passed the strength criterion set by the ACI 318-19 building code. The resulting pattern shows an increment in the mechanical and durability properties compared to the reference mix when (50% desert sand + 50% recycled crushed sand) is combined with 5-12.5% silica fume. The optimum result was achieved when the optimized, sustainable sand ratio (50% desert sand + 50% recycled crushed sand) was combined with 10% silica fume. It can be concluded that the prepared concrete has excellent results in terms of concrete strength and durability properties. Furthermore, this study shows that 100% of natural sand and 10% of cement can be saved using the optimal proposed concrete design mix. This study would have explored sustainability in the Saudi region by utilizing a vast percentage of vacant desert sand in concrete manufacturing. Doi: 10.28991/CEJ-2025-011-01-012 Full Text: PD
Safety Risk Assessment Model for Bridge Construction
No full textIn Indonesia, construction accidents have occurred during the construction of bridges and elevated roads, peaking in 2017. The lifting of girder beams has failed in several construction projects, and the formwork has failed during pier construction. The reasons for these work accidents are human and equipment factors, which caused material losses and loss of life. A risk assessment model for bridge construction work accidents in construction projects is proposed in this paper, with the work breakdown structure (WBS), risk breakdown structure (RBS), analytic hierarchy process (AHP), and rating being integrated to assess the risk of bridge construction work accidents. This model is expected to improve safety in bridge construction by providing effective safety planning, especially in the accident risk assessment process. The study results indicate that the WBS and RBS can outline and explain the identification of construction safety risks for bridges and provide insight into the interrelationship of construction phases and the potential risks. The relationship between the WBS and RBS is created in the form of a coupling matrix, and we identify the potential risky activities at each phase and the corresponding construction phases. The AHP can be used to calculate the weights and priorities of the WBS and analyze the magnitude of the risk index for its related risky activities; then, the rating method can be used to analyze the risk index. Girder and diaphragm installation work involves a high risk of workers falling during the erection of girders. Doi: 10.28991/CEJ-2025-011-01-010 Full Text: PD
Experimental and Numerical Analysis of Punching Shear of GFRP-RC Slabs
No full textThis study investigates the punching shear behavior of Glass Fiber-Reinforced Polymer (GFRP)-reinforced concrete slabs, addressing critical gaps in current design guidelines for high-strength concrete (HSC). The objective is to evaluate the impact of concrete strength, including normal-strength concrete (NSC, 30 MPa) and HSC (60 and 90 MPa), on the punching shear resistance, bridging the lack of experimental data that limits the use of HSC in FRP-reinforced slabs. The research employs experimental testing on three full-scale slab specimens (1.5 m í— 1.5 m í— 0.1 m) under concentric monotonic loading until failure, coupled with Finite Element Analysis (FEA) using the Concrete Damage Plasticity (CDP) model in ABAQUS. Key findings reveal that increasing concrete strength moderately enhances punching shear resistance by 5.6% and 8.9% for 100% and 200% strength increases, respectively. The FEA model successfully replicates load-deflection behavior, crack patterns, and failure mechanisms with less than a 3% deviation from experimental results. This study enriches the literature with experimental data on GFRP-reinforced slabs using HSC and verifies FEA as a robust design tool for engineers. The findings contribute to developing comprehensive design guidelines for FRP-reinforced slabs subjected to punching shear in high-strength applications. Doi: 10.28991/CEJ-SP2024-010-017 Full Text: PD