Civil Engineering Journal
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2007 research outputs found
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Pre- and Post-Cracking Resistance of Steel Fiber Reinforced Concrete Flexural Members with GFRP Bars
No full textThis research investigates the pre- and post-cracking resistance of steel fiber-reinforced concrete specimens with Glass Fiber Reinforced Polymer (GFRP) bars subjected to flexural loading. The purpose is to modify the ductility and cracking resistance of GFRP-reinforced beams, which are prone to early cracking and excessive deflections instigated by the low modulus of elasticity of GFRP. Six self-compacting concrete specimens (1500×240×200 mm), incorporating steel fibers of two lengths (25 mm and 40 mm) with varying distribution depths, were tested to assess their structural performance. The results indicate significant enhancements in cracking resistance, stiffness, energy absorption, ductility, and flexural strength. Tested beams reinforced with 40 mm-long steel fibers exhibited a 23.9%–24.2% development in the ultimate moment capacity associated with the steel-reinforced specimens, whereas those with 25 mm fibers showed smaller increases (2.7%–3.1%). The cracking resistance improved by up to 33.3% in beams with 40 mm-long fibers and by 16.67%–20% in those with 25 mm-long fibers, associated with a non-fibrous GFRP specimen. Additionally, the inclusion of 40 mm hooked-end steel fibers significantly enhanced ultimate deflection, with peak deflections increasing by 30.2%–44.8% compared to steel-reinforced beams. Fibrous GFRP-reinforced beams exhibited up to 154% higher energy absorption under ultimate load than a non-fibrous GFRP beam. All fibrous GFRP-reinforced beams achieved deformation-based ductility indices between 4.2 and 6.9, exceeding the minimum threshold of 4 for adequate deformability. These findings confirm that incorporating 40 mm steel fibers significantly improves the structural behavior of GFRP-reinforced concrete specimens, offering valuable insights for optimizing their design
A Study on the Impact of Crystalline Hydrophilic Additive and Microcapsules on Concrete Freeze-Thaw Durability
No full textThis paper evaluates the effectiveness of a crystalline hydrophilic additive and chemical microcapsules in enhancing concrete’s freeze-thaw resistance at both material and structural levels. Three concrete mixes were tested: a reference mix, one with the crystalline additive and one with microcapsules. Cubic specimens were tested for compressive strength, water absorption and relative dynamic modulus of elasticity before, after and during 56 freeze-thaw cycles (according to CEN/TR 15177). The reinforced concrete beams underwent the same freeze-thaw regime and were tested under displacement-controlled cyclic loading to evaluate residual capacity and serviceability. Although both additives improved freeze-thaw resistance, beams with the microcapsule performed better on most criteria, including increased stiffness (+14%), load-bearing capacity (up to +22%) and ductility after freeze-thaw loading. Notably, all mixes showed an unexpected increase in compressive strength after cycling. Although the microcapsules provided the best overall performance, the crystalline additive was more effective in reducing water absorption. The study highlights the practical applicability of microcapsules for structural elements and demonstrates their potential to improve performance properties under harsh environmental conditions. The research novelty lies in the dual-level evaluation – material and structural – and the systematic comparison of two innovative additives, allowing a more comprehensive understanding of their performance under freeze-thaw conditions
Geomechnical Characterization of Lateritic Soil by Combining Crushed Granite and Low Content of Cement
No full textLateritic soils, which are widespread in intertropical regions and traditionally used as pavement sub-base layers in Burkina Faso, often exhibit low geomechanical performance, thereby limiting their long-term durability under increasingly heavy traffic loads. This study investigates a combined stabilization approach consisting of incorporating 20% of 10/20 crushed granite aggregates together with low cement content (0%, 1%, 2%, and 3%). The objective was to improve both the mechanical properties and fracture behavior of these soils, while reducing the environmental footprint associated with cement use. Accordingly, an experimental program was carried out, including geotechnical tests (maximum dry density, optimum moisture content, and CBR at 95% compaction) and mechanical characterizations (unconfined compressive strength, indirect tensile strength, Young’s modulus, and full stress–strain behavior under uniaxial compression). The results revealed substantial improvements when 20% aggregates and 3% cement were added to the raw soil: the maximum dry density increased by approximately 5%, the CBR by 2253%, the compressive strength by 134%, the indirect tensile strength by 85%, and the Young’s modulus by 195%. Regarding fracture behavior, the same mixture showed an enhanced energy absorption capacity, with increases of approximately 40% for fracture energy, 65% for peak energy, 87% for elastic energy, 18% for plastic energy, and 5% for post-peak energy. These findings confirm that the combination of crushed aggregates and low cement content produces a synergistic effect, yielding a material that is stronger, stiffer, more water resistant, and more ductile. Thus, innovative stabilization approach represents a promising alternative for sustainable road construction
Multi-Spring Model and Pushover Analysis of Masonry-Infilled Wall in RC Frame Under Tsunami Loading
No full textThis study investigated the behavior of masonry-infilled walls (MIWs) within reinforced concrete (RC) frames when exposed to hydrodynamic forces from tsunamis by employing a multi-spring modeling approach across different inundation levels. The proposed analytical model divided the MIW into 1 to 5 horizontal nonlinear spring elements that were allocated along the wall's height. Each spring represented a segment of MIW and was defined by a tri-linear force–displacement relationship. The model was calibrated with the experimental data from previous studies and was analyzed using pushover assessment under uniformly distributed hydrodynamic forces corresponding to four tsunami inundation levels (0.25H, 0.50H, 0.75H, and 1.00H). The models, which had employed four or five horizontal springs, had most effectively replicated MIW behavior under tsunami loading at all inundation depths. Conversely, single-spring models tend to overestimate lateral resistance by up to 50%, particularly when the frame is only partially submerged. This discrepancy arises because less force is transmitted through the MIW, with a greater amount of it being transferred directly to the foundation. The utilization of several spring elements provided a realistic load path, improved the interaction between the frame and MIW characterization, and optimized the precision in simulating lateral resistance and post-peak behavior
Recycled Steel Fiber-Reinforced Mortar with Embedded Structural Health Monitoring for Sustainable Construction
No full textThe study examines the mechanical and microstructural performance of eco-friendly mortar mixes that incorporate Recycled Steel Fibers (RSF) derived from waste tires. Four mortar formulations with varying RSF content (0%, 0.5%, 1%, and 1.5% by volume) were evaluated for compressive strength, flexural strength, and electrical conductivity. Experimental results revealed that a 1.5% RSF mixture exhibited remarkable improvements in flexural strength, achieving a 67% increase compared to the control formulation while delivering a 12.6% enhancement in compressive strength. However, the 0.5% RSF mix showed reduced performance due to poor fiber dispersion, underscoring the importance of proper fiber distribution. Specific resistance decreased with RSF addition, indicating enhanced electrical conductivity, with the lowest specific resistance observed at 0.5% RSF on day 28. An empirical model using a fiber reinforcing index (ξ) was developed to predict strength behavior. A quadratic relationship was found to best describe compressive strength gains, while a linear model effectively captured the flexural strength trend. The models were calibrated using both experimental data and literature values, achieving high predictive accuracy. Electrical conductivity increased with RSF addition, and the slope of the specific resistance during loading correlated strongly with mechanical strength, highlighting its potential as a non-destructive structural health monitoring (SHM) indicator. SEM analysis confirmed improved matrix integrity and fiber–matrix interaction at the optimal 1% RSF content, which balanced strength gains and sensing capability. The study establishes RSF as a viable sustainable alternative to virgin steel fibers, providing both mechanical enhancements and self-sensing properties. This novel integration of electrical monitoring with mechanical testing and modeling provides new insights into recycled-fiber composites by enabling simultaneous enhancement of structural performance and real-time damage monitoring
Experimental Assessment of Ground Thermal Properties for Shallow Geothermal Energy
No full textGeothermal energy, being clean and renewable on both large and small scales, has become a field of interest for researchers in several areas such as cooling-heating systems, geothermal piles, and geothermal electricity. The purpose of this study is to explore the ground thermal behavior and relevant thermal soil properties for key regions in Jordan. These regions represent either major cities or areas with optimal seasonal temperature variations suitable for such applications. Three key locations were investigated: Tabarbour-Amman, Shafa-Badran-Amman, and Mafraq. Geotechnical soil investigations were conducted using hollow stem auger drilling, with soil samples collected at each meter of depth. Each sample was tested in the laboratory for thermal diffusivity, heat capacity, specific heat, and thermal conductivity. Additionally, thermocouples were installed in each borehole, and the holes were backfilled with the soil cuttings produced during drilling. Seasonal temperature profiles were developed for each site based on the measurements from the thermocouples. Temperature variations were also analyzed using the measured thermal soil properties within a mathematical heat transfer model, with results showing good agreement with the recorded measurements. Thermal diffusivity ranged from 0.315 to 0.365 mm²/s near the ground surface, and from 0.135 to 0.257 mm²/s at a depth of six meters. Thermal conductivity ranged from 0.197 to 0.351 W/m·K near the surface to 0.468 to 0.875 W/m·K at six meters depth. Ground temperature varied from a maximum during the hot season at the surface to a minimum during the cold season at six meters depth. The extreme temperature difference (4.4 to 5.25 °C), along with the observed values of diffusivity and heat capacity, indicates significant potential for energy extraction in the form of heat, in a cost-effective and time-efficient manner
Improving the Performance of Shallow Footing Subjected to Uplift Loading Using Structural Skirt
No full textThe increasing demand for internet and phone services had required the construction of transmission towers in various terrains, including loose sand, which was often found in desert areas and exposed to wind loads that can pull out these towers. This study aims to improve the uplift resistance of shallow footings subjected to pure uplift forces. In this research, a loading system with a data logger, a shallow footing model, and skirts with different shapes, lengths, and inclination angles was used. The performance and behavior of unskirted footing resting on loose sand with 30% relative density were analyzed and compared with skirted footing under uplift loads. The results showed that increasing the L/B (where L is the footing length and B is the footing width) up to 2 and the inclination angles up to 45° of the skirt gave a significant increase in uplift resistance for skirts with straight corners by 26 times and 19 times for chamfered corners, compared with unskirted footing. It is noted that increasing L/B has less effect than increasing inclination angles by recording 6 times with L=2B and 0°. Skirt footing with straight corners demonstrates better performance than chamfered corners
Bio-Based Modification of Natural Rubber-Modified Asphalt Using Hard Resin from Yang
No full textThis study investigates the potential of hard resin derived from the Yang tree (HY), a renewable bio-based byproduct, as a performance-enhancing additive in natural rubber-modified asphalt (NRMA). HY-modified binders (HYMA) containing 3%, 7%, and 15% HY by weight were evaluated through a multi-scale experimental program, including physical, rheological, thermal, chemical, and mechanical tests. Standard binder characterizations (penetration, ductility, softening point, viscosity), spectroscopic analyses (FT-IR, NMR), microstructural observations (ESEM, XRD), thermal profiling (DSC), and performance assessments (DSR, Marshall) were conducted. The results demonstrated that HY improved binder properties at optimal concentration by introducing additional hydrocarbon structures without chemical cross-linking. HYMA3 achieved the most favorable balance of stiffness, flexibility, and compaction efficiency, whereas higher HY contents (≥7%) impaired structural integrity and deformation resistance. Microstructural and thermal evidence confirmed surface modifications and altered thermal transitions, which influenced viscoelastic response. These findings provide new insights into bio-resin–asphalt interactions and establish the viability of HY as a sustainable alternative to synthetic polymer modifiers. Beyond performance improvement, HY promotes circular construction by transforming agricultural byproducts into functional pavement materials, supporting the development of climate-adaptive infrastructure
The Effect of Fiberglass Paint Coating on the Shear and Flexural Strength of Concrete Blocks
No full textThis study uses an experimental method to investigate the behavior of concrete blocks coated with fiber paint, focusing on their shear and flexural strength, ductility, stiffness, and energy dissipation to enhance their mechanical performance. The fiber paint coatings used in this study were applied in different thicknesses, namely 1 mm, 2 mm, and 3 mm. The results show that a 3 mm coating provided the highest improvement, with shear and flexural strengths increasing by 47.36% and 66.06%, respectively. Flexural ductility improved by up to 32%, while stiffness increased by 12% in flexure and 13% in shear. Energy dissipation also showed significant enhancement; total flexural energy increased from 1.38 kNmm to 10.76 kNmm at 3 mm, and shear energy dissipation reached 50.72 kNmm at 3 mm. These results confirm that fiber paint can enhance the shear and flexural strength, ductility, stiffness, and energy dissipation of concrete blocks. This study introduces fiber paint as a practical reinforcement method for concrete block materials, offering a simple, easy-to-apply, and cost-effective alternative that improves both mechanical and aesthetic performance
Life Cycle Assessment of Phosphogypsum as Filler Material for Coal Fly Ash-Based Geopolymer
No full textThe global accumulation of phosphogypsum (PG), with annual generation exceeding 175 Mt/year, presents significant environmental challenges. While studies have demonstrated PG's potential as a filler material in geopolymer composite, comprehensive environmental impact assessments of such valorization approaches remain limited. This study presents the first comparative life cycle assessment (LCA) of acid- and alkali-activated PG-CFA geopolymers in the context of sustainable industrial waste management. Geopolymer technology can eliminate the need for traditional landfilling of PG in coastal areas and, therefore, reduce their negative environmental impacts. LCA was conducted to assess the impacts of repurposing 1kg functional unit of PG as geopolymer precursors coupled with acid- and alkali-based activators compared to the current disposal practices of these solid wastes. The inventory was modeled after a phosphoric acid plant using the wet dihydrate process, a coal-fired power plant, and a laboratory-scale coal fly ash-phosphogypsum geopolymer (FAPG) synthesis upscaled for industrial application. The most number of environmental benefits was observed for acid FAPG particularly via reductions in CO2-eq emissions by 40%, 90% in energy consumption, and 36% in mineral resource extraction. Alkali FAPG excelled in water acidification and scarcity by 60% and it could outperform acid FAPG environmentally via sensitivity analysis under a similar formulation blend. Further research can focus on optimizing FAPG formulation, finding alternatives for the acid and alkali activators, and reviewing industrial standards for widespread FAPG applications. These results imply the potential of integrating FAPG manufacturing in PG- and CFA-generating industries to emulate a circular economy