Abstract Interlayer bonding in flexible pavements has an essential influence on their structural strength and performance. In this study, the combined outcome of application rate of tack coat and the condition of geotextile coverage on the interlayer shear strength (ISS) and the rutting resistance of double-layer asphalt systems is investigated. Specimens of binder and wearing courses were prepared with CSS-1H (cationic slow-setting asphalt emulsion, low-viscosity grade, with harder asphalt residue) emulsified tack coat at amounts of 0, 0.3, 0.6, 0.9 and 1.2 L/m 2 . Three interface patterns of geotextile coverage were tested; unreinforced, 50% and 100%. The bonding between layers was assessed by direct shear bond test, and the rutting resistance was evaluated by wheel tracking test. Results revealed that the optimal amount of tack coat was highly dependent on the interface condition. Unreinforced specimens achieved the maximum ISS of approximately 1083.89 kPa at 0.3 L/m 2 , while the geotextile-reinforced mixes required higher tack coat rates to develop sufficient bonding due to emulsion absorption by the geotextile. In general, control specimens showed higher ISS values compared to specimens compromising geotextile between layers, but there is a significant enhancement in resistance to permanent deformation for specimens modified with geotextile with a sufficient amount of tack coat. The full geotextile coverage with 1.2 L/m 2 tack coat resulted in the best rutting performance, reducing the rut depth by approximately 28% when compared with the optimum unreinforced condition. At its optimum tack coat application rate of 0.9 L/m 2 , partial geotextile coverage achieved a 17.4% reduction in rut depth relative to the optimum unreinforced condition, indicating a potentially economical alternative. The results emphasize the need to optimize the application rate of tack coat and geotextile coverage to provide balanced interlayer bonding and rutting resistance of asphalt pavements.
Abstract This study presents a detailed experimental investigation of rigid concrete pavement slabs constructed with high-performance concrete (HPC) reinforced using steel, polypropylene, and hybrid fibres under simulated earthquake loading conditions. The research aims to evaluate the energy dissipation capacity, crack resistance, and structural behaviour of fibre-reinforced HPC slabs subjected to seismic actions. Fiber reinforcement, especially steel fibres, has been recognized as an effective method for enhancing the durability and service life of concrete pavements due to its positive influence on mechanical properties and load-transfer performance. Rectangular slab specimens measuring 1000 × 800 × 50 mm were prepared using HPC mixtures containing different volumetric percentages of steel fibres (0.25%, 0.75%, and 1.0%). Control specimens without fibre reinforcement were also tested for comparison. The results from hysteretic loop analysis under cyclic loading demonstrated that hybrid slabs reinforced with 0.25%–0.75% steel–polypropylene fibers achieved improved post-yield behaviour and greater energy absorption capacity. In addition, fiber bridging across cracks maintains load transfer after initial cracking, leading to gradual and ductile failure rather than sudden brittle collapse. Overall, the findings confirm the effectiveness of hybrid fibre reinforcement in improving the seismic performance and durability of HPC pavement slabs.
Abstract This study examined the effects of the amount and particles size of Crumb Rubber (CMR), surface treatment with NaOH, and inclusion of micro hook-end steel fiber (MSF) on the performance of lightweight self-compacting concrete (LWSCC). Two types of lightweight aggregates (Lightweight Expanded Clay Aggregate (LECA) and Artificial Attapulgite Aggregate (ATG)) were used as coarse aggregates, with CMR (two particle sizes: 1–3 mm and 3–5 mm) replacing natural sand at a volume percentage of 10–30%. A portion of the rubber was surface treated with NaOH, and 0.5% MSF was added to some mixtures. The findings revealed that the ATG-based mixtures exhibited acceptable mechanical properties, with approximately 11% and 21% higher compressive strength and modulus of elasticity than the LECA-based mixtures, respectively for structural lightweight concrete application. The strength decreased by 35% with an increase in the CMR content, whereas the impact ductility improved notably (up to 83%). Finer rubber particles exhibited better performance. While NaOH treatment partly recovered strength and improved ductility, the addition of MSF boosted the impact resistance and improved the tensile and flexural strengths by up to 29%. All mixtures met the EFNARC standard requirements for fresh properties, proving that ATG-based LWSCC with CMR and steel fibers provides a more impact-resistant, structurally sound, and sustainable solution for structural applications.
Abstract In this study, steel waste is used as a sustainable replacement for quartz sand in high-performance concrete (HPC). Fifteen concrete mixes were prepared with 0%, 25%, 50%, 75%, and 100% as volume replacement of steel waste, with steel fibres added at 1%, 2%, and 3%. The experimental program included workability, compressive strength, splitting tensile strength, direct tensile strength, flexural strength, and density tests, in addition to microstructure analysis using scanning electron microscopy. The results showed that optimal performance was achieved when 50% of the steel waste was replaced with 3% steel fibres. The compressive strength of this mix was 118.6 MPa, the direct tensile strength was 16.62 MPa, the splitting tensile strength was 16.61 MPa, and the flexural strength was 20.16 MPa. Compared to the reference mix, compressive strength, direct tensile strength, and splitting tensile strength increased by 22.6%, 25.9%, and 36.7%, respectively. Higher replacement levels (75–100%) led to strength reductions due to weaker interfacial bonding and increased mix heterogeneity. In addition, steel waste increased concrete density, reaching heavyweight concrete at high replacement ratios. Overall, the findings indicate that a 50% replacement of quartz sand with steel waste provides the best balance between sustainability and mechanical performance in HPC.
Abstract One of the main reasons for pavement deterioration and shortened service life in road networks is adhesion failure. The application of additives has been shown to be a successful strategy for increasing pavement durability and resistance to such failures. The purpose of this study is to assess the performance characteristics of an asphalt concrete (AC) mixture that has been submerged in water for an extended period utilizing the Tough Fix Hyper (TFH) addition. In order to do this, the Dynamic Shear Rheometer (DSR) and standard binder tests were used to evaluate the conventional properties of TFH modified asphalt binder. The findings showed that the binder's mechanical, rheological, and physical characteristics are not considerably changed by the addition of TFH. A stripping test was used to evaluate binder film retention on aggregate surfaces to determine moisture susceptibility. Interestingly, The TFH-treated mixtures showed no stripping even after being submerged in water for a whole year at 25°C. Marshall Stability (MS) and Flow, moisture damage resistance, Wheel Tracking (WT), and Indirect Tensile (IDT) strength tests under long-term water immersion were used to further assess the mechanical performance of AC mixtures including the TFH additive. When compared to the control mixture, the results showed that the TFH-modified mixtures' physical performance significantly improved. In particular, IDT strength rose by almost 33% and rut depth decreased by about 28.8%. Furthermore, the TFH additive demonstrated increased resistance to moisture-induced damage by improving the mixture's IDT strength during prolonged water immersion. Overall, the results show that adding 0.15% TFH to AC mixtures greatly improves their longevity and performance when compared to unmodified mixtures.
Abstract When constructing tunnels through dense hard rock, it is common for the adjacent rock strata to sustain fracturing. Such damage can readily precipitate severe underground construction mishaps, including occurrences of rockburst, spalling, and substantial deformations within the surrounding geological material. Employing in-field monitoring results from a subterranean research facility and numerical simulations conducted with the CASRock software, this study examines the developmental behavior and damage mechanisms inherent in the surrounding rock mass of a deep, hard-rock tunnel experiencing excavation-induced perturbations. The analysis reveals: Time-dependent rock fracturing occurs mainly in high differential stress areas with distinct directionality, driven by directional crack propagation under a true triaxial stress field; stress corrosion further promotes directional crack extension when stress reaches a critical level, enhancing this directionality. Rock mass damage is significantly correlated with its strength and integrity: high-strength intact rock masses (Grade II, RMIBT 0.75–0.90) show excavation-induced new crack propagation, while low-strength fractured ones (Grade III, RMIBT 0.50–0.75) are dominated by existing fracture expansion. During tunnel excavation, spandrel and haunch areas are core maximum principal stress concentration zones where stress accumulates with advancement; targeted advanced support or reinforcement here can effectively reduce rockburst risk and ensure construction safety. Three typical surrounding rock fracture modes (single-zone, zoned, deep-seated) are regulated by the coupling of rock mass physical-mechanical properties and excavation-induced stress redistribution. The excavation damage zone (EDZ) evolves in four distinct stages with clear quantitative thresholds, providing a scientific basis for optimizing excavation speed and determining support timing.
Abstract This study investigates a non-contact detection method that combines Laser Doppler Vibrometry (LDV) with acoustic excitation to efficiently identify the locations of cavities within tunnel linings. By comparing the vibration response characteristics of hammer excitation and acoustic excitation, it is found that acoustic excitation is better than traditional hammer excitation in terms of vibration stability, frequency distribution range and non-damaging. The study further examined the vibration behaviour of specimens containing cavities of different sizes, depths, and measurement distances. The results show that the increase of cavity size leads to a significant increase in vibration amplitude and a decrease in bending resonance frequency, while the increase of depth leads to a decrease in vibration amplitude and an increase in characteristic frequency, showing obvious correlation with geometric parameters. Furthermore, in long-distance detection scenarios, while vibration amplitude exhibits exponential decay with distance, the resonance frequency shift remains consistently small. This demonstrates that frequency characteristics can serve as a stable defect identification criterion. Ultimately, velocity analysis enables precise detection of void boundaries, validating the method's effectiveness. This study provides a high-precision, non-contact technical solution for diagnosing hidden defects in concrete structures. Experimental data shows its cavity recognition accuracy rate is notably high, demonstrating significant engineering application value.
Abstract Widespread usage of concrete and increasing construction waste have negative environmental impacts. Therefore, reducing concrete consumption and recycling construction waste has become essential for improving the environment and promoting sustainability. This study adopts a sustainability approach by reducing concrete consumption in slabs, the largest structural elements, and reusing recycled concrete. Five identical slab specimens were cast. One was solid, and four were longitudinally hollow. Results of comparing longitudinal and transverse voids' direction showed that the longitudinal voids achieved the highest load and the least deflection. Four proportions of recycled concrete aggregate (RCA) for replacing the normal coarse aggregate (NCA) at 0, 25%, 50%, and 75% was adopted. Test results show that the solid slab failed in flexural, while hollow-core slabs failed in shear. The high reinforcement ratio of the hollow-core slab increased its loading capacity and decreased deflection. The cracking and peak loads of the hollow slab with no RCA were approximately 13% and 23.5% lower than those of the solid slab, while the deflection was identical. Replacing 25% and 50% of the NCA with RCA did not significantly affect the hollow-core slab's peak load. A 75% RCA content had a more significant impact on loading capacity, resulting in a 25% decrease. Therefore, the weight reduction compared to the loading capacity reduction was economical and more sustainable. The numerical analysis results showed that when the reinforcement ratio was reduced by 60%, the failure mode of all hollow-core slabs shifted from shear to flexure, and the cracking load decreased by 10% to 16% compared to slabs with a high reinforcement ratio. The analysis reveals that increasing the ultimate load by shortening the void length shifts the failure mode from shear to flexure, with higher ductility and energy absorption.
Abstract This study explores making sustainable bio-bricks using materials readily available in the local environment: clay, sand, lime, termite mound soil (TMS), and rice husk. The present study examined these materials, both individually and when combined, to understand their microscopic structure, mineral composition, and thermal stability. Scanning electron microscopy (SEM) revealed a dense, tightly bonded structure in the composite bio-brick, with well-fitted particles enhancing its strength. X-ray diffraction (XRD) confirmed this, identifying the main crystalline phases in the bio-brick: quartz, kaolinite, portlandite, and amorphous silica. The presence of these minerals suggests excellent chemical compatibility among the components, enabling the material to undergo effective reactions that promote hardening and strength development. Thermogravimetric analysis (TGA) revealed the material's thermal stability, showing it remains stable even above 540°C. This composite performs well under high temperatures, but it excels when the mixture is precise: 45% clay, 22% sand, 6% termite mound soil, 12% lime, and 15% rice husk. At these ratios, it absorbs the least amount of water—just 14.15%—and achieves a compressive strength of 7.56 MPa. Importantly, these bio-bricks demonstrated a significant reduction in global warming potential, decreasing CO 2 emissions by 95% compared to traditional bricks. This study highlights the potential of utilizing local resources to produce sustainable building materials, contributing to eco-efficient construction practices and reducing reliance on non-renewable resources. The findings suggest that bio-bricks could offer a viable alternative for low-income housing, fostering local economic development and promoting environmentally sustainable building solutions.
Abstract Use of hybrid-polymer binders is important to minimize the failure of asphalt pavements due to temperature variations. So, this research assesses the performance of asphalt mixtures with the modification of styrene-butadiene-styrene (SBS) and polyethylene glycol (PEG) as single and hybrid-polymer binders. The SBS content in the asphalt binder was 2%, 3%, and 4% and the PEG content, 1.5%, 2.5%, and 3.5% by weight of binder. Further, SBS-PEG blend binders were also developed to assess the effect of their combination on the properties of asphalt binder and mixture. Asphalt binder tests were done to measure the change in consistency and tensile strength of the asphalt binder. While, testing of the mixtures' performance was done via splitting test in dry and wet conditions to measure their water resistance, as well as wheel tracking test to measure rutting resistance. It was observed that the mixtures containing 4% SBS and 3.5% PEG (SP3) had the highest softening point and the lowest penetration value, suggesting increased strength and thermal stability. Hybrid modified mixtures demonstrated improved strength and moisture resistance, with SP3 mixture showing the maximum splitting strengths (1588 and 1470 kPa under dry and wet conditions, respectively) and a better strength ratio than the control mixture. The rutting test also showed an improvement in permanent deformation, with rut depths of 1.4–1.44 mm for the modified mixtures compared to 4.49 mm for unmodified mixture. The hybrid polymer method could be a potential solution to increase the life of pavements in areas with high traffic and harsh climatic conditions.
Abstract The strategic use of replaceable structural fuses is pivotal for achieving seismic resilience, as it localizes damage and facilitates post-earthquake repair. This study addresses a critical gap in the design of steel Knee-Braced Frames (KBFs) by systematically quantifying the influence of the knee element's length a key yet poorly understood parameter on the global seismic performance. Through a detailed finite element parametric study in ABAQUS, validated against experimental results, we demonstrate a fundamental performance trade-off: while longer knee elements successfully protect primary columns by concentrating plasticity, they precipitate a severe degradation in initial stiffness (up to 41%) and energy dissipation capacity (up to 79%). To mitigate this limitation, we propose a novel enhanced KBF system incorporating supplemental supports that enable a dual-phase response. This system functions as a conventional KBF under moderate seismic demands, while the supports engage during intense shaking to provide a secondary stiffening mechanism and enhance energy absorption. Nonlinear dynamic analysis under the Northridge earthquake record confirms the superiority of the proposed system, showing a 38.14% reduction in peak lateral displacements compared to the conventional configuration. Our findings provide both a critical understanding of KBF geometry-performance relationships and a practical, optimized design solution for enhancing structural resilience.
Abstract Base isolation (BI) is a proven technique for reducing seismic demands on buildings, enhancing resilience, and maintaining post-earthquake functionality with minimal repairs. However, its effectiveness on soft soil remains uncertain due to soil–structure interaction (SSI), which can alter the building’s fundamental period and compromise the benefits of BI. This issue is critical, as many densely populated, high-seismicity cities are located on soft soil. This study investigates a 13-story building equipped with a lead–rubber bearing (LRB) isolation system on soft soil using nonlinear time-history analysis (NLTHA) that explicitly incorporates SSI effects. The results show that the BI system significantly increased the fundamental period by approximately 114% and reduced base shear by up to 47%. In addition, inter-story drift and peak acceleration were reduced by up to 49% and 48%, respectively. On the other hand, SSI increased base shear by up to 52% in the fixed-base model and approximately 76% in the base-isolated model. SSI also increased peak acceleration by up to 14% and 13% in the fixed-base and base-isolated models, respectively, highlighting its adverse impact on structural performance. Nevertheless, the BI system remained effective in mitigating seismic demands even in the presence of SSI. These findings emphasize the importance of incorporating SSI in seismic analysis and support the applicability of BI systems for high-rise buildings on soft soil.
Creep effects in rock engineering have long been the focus of attention and key research contents for civil engineers at home and abroad. In this manuscript, the Dadu River Crossing Bridge Chengdu bank engineering slope in southwest China was taken to be the research object. In this slope, the high geostress and tectonic stresses caused the rock layers to crush each other, thus forming crushed rock. Which may undergo creeping deformation under long-term loads. Firstly, in this manuscript, the creep patterns of rock mass under different stress states (Ratio of rock stress to rock strength) was summarized based on the octahedral strength theory. Secondly, an accurate calculation of the rock mass strength parameters (uniaxial compressive strength) was realised based on the Hoek-Brown strength criterion. Thirdly, synthesized the theoretical study of the rock mass creep patterns and the calculation method of rock mass strength parameters, and then combined it with numerical analysis, an analytical model for rock mass creep patterns at different burial depths was established. Finally, the model was used to evaluate the rock mass creep behaviour of the research object at different depths of burial. The research results can provide a reference for the creep analysis of crushed rock and provide a basis for the safe construction of engineering slopes.
Recent climate events have become increasingly unpredictable, emphasizing the need for climate model projections with reliable performance. Future climate projections derived from the Shared Socioeconomic Pathways of Coupled Model Intercomparison Project Phase 6 require careful evaluation against historical observations to ensure their applicability. This study evaluates six CMIP6 historical simulations namely ACCESS-CM2, CNRM-CM6-HR, EC-Earth3, EC-Earth3-Veg, HadGEM3-GC31-MM, and MPI-ESM1-2-HR using cases in Indonesia. Model performance was assessed using the SA-OBS dataset with a horizontal resolution of 0.25 degrees. Five evaluation metrics were applied namely Taylor Skill Score, Interannual Variability Score, normalized Mean Absolute Error, Kling Gupta Efficiency, and Willmott Index. These metrics were synthesized using the Bergen Metrics framework to provide an integrated measure of model performance. In addition, a rank based weighting approach was employed as a comparative assessment. Results indicate that all models show limited skill in simulating precipitation, while minimum, mean, and maximum temperatures are reproduced more accurately. Across all variables, EC-Earth3-Veg consistently achieved the best overall performance, followed closely by EC-Earth3. The remaining models exhibited comparable performance but ranked lower. These findings are consistent with previous regional evaluations over Southeast Asia. The relatively strong performance of EC-Earth3-based models is likely associated with their finer spatial resolution. Overall, this study demonstrates that Bergen Metrics provide a robust and flexible framework for climate model evaluation, while rank based weighting offers complementary insight into relative model consistency.
This study presents an experimental investigation on the rehabilitation of fire-damaged reinforced concrete (RC) columns through the removal of the deteriorated concrete cover, its replacement with new normal-strength concrete (NSC), and subsequent full wrapping using carbon fibre-reinforced polymer (CFRP) sheets. The columns were tested under an eccentric load with an eccentricity of e = 90 mm. The experimental program consisted of nine short RC column specimens classified into two groups according to fire exposure temperatures of 500 degrees C and 700 degrees C, using a specially designed furnace. In addition, one unexposed control column was tested for comparison. Two fire exposure durations, namely 60 and 120 min, were considered. During fire exposure, the columns were subjected to a pre-applied axial load equal to 50% of the ultimate load capacity of the unexposed control specimen. The experimental results showed that the ultimate load-carrying capacity of the columns decreased with increasing fire temperature and exposure duration. Specifically, columns exposed to 500 degrees C and 700 degrees C for 60 and 120 min showed reductions in load-carrying capacity of (11.65%), (14.11%), (20.85%), and (36.8%), respectively, relative to the control column. After rehabilitation using the adopted technique based on NSC replacement and CFRP wrapping, the fire-damaged columns showed improvements in ultimate load-carrying capacity ranging from (32.14%) to (66.02%) relative to the corresponding fire-exposed specimens.
To study the catastrophic mechanism of water inrush and mud outburst disasters encountered during tunnel excavation involving pipe-like water-rich structures, the research combined theoretical analysis with model experiments to construct a three-dimensional experimental model. This study investigated the catastrophic mechanisms of water inrush and mud outburst in pipe-like water-rich structures, analyzed the evolution laws of these disasters during their formation process, and achieved the following main results: 1) Throughout the entire process of water inrush and mud outburst disasters, the evolution of the disaster mainly consists of three stages, including the initiation of water-conducting channels, erosion and enlargement of water-conducting channels and instability stage, reflecting the formation, development, and disaster-causing evolution of water inrush and mud outburst. 2) Tunnel excavation caused a gradual decrease in the permeation water pressure of the surrounding rock under the initially stablewater pressure field. Meanwhile, as the disturbance from tunnel excavation progressed, the permeation water pressure in the filling medium also gradually decreased, with an increasing rate of decline. 3) During the occurrence of water inrush and mud outburst, there were noticeable stage-like changes in displacement, permeation water pressure, and stress-strain parameters in the tunnel and karst channels. The displacement and stress-strain information of the surrounding rock before the occurrence of water inrush and mud outburst in the tunnel was particularly sensitive, serving as a predictive standard for the precursory information of tunnel water inrush and mud outburst.
Additive manufacturing is increasingly being used in areas not traditionally associated with this type of technology, such as 3D printing of concrete or clay. This study focuses on the experiences with the 3D printing process for these materials. The goal was not to create final construction or artistic works, but rather to verify the capabilities of the equipment and solutions, prepare basic material recipes, and explore the practical challenges of working with printing mixtures and materials. As part of the experiments, architectural test samples were printed from both clay and geopolymer composites, which were used to verify the behaviour of the material during printing and after curing.
Owing to the reduced shear stiffness of corrugated steel webs (CSWs), shear deflection must be accounted for in estimating the total deflection of box girders with CSWs (BGCSWs). Most existing investigations into the deflection behaviour of such girders are based on prismatic girder models, in which the CSWs are presumed to resist the entire external shear force - thus contributing to shear deflection - while the concrete flanges provide only flexural rigidity, leading to bending deflection. In contrast, in tapered BGCSWs, bending moment induces a redistribution of shear stresses within the cross-section, resulting in a deflection mechanism that fundamentally deviates from predictions by conventional methods. Furthermore, unlike prismatic girders, the moment of inertia in tapered girders varies continuously along the span, significantly increasing the complexity of bending deflection computation. To extend classical beam theory to the analysis of tapered BGCSWs, this paper introduces the concept of an equivalent effective moment of inertia derived via Simpson's integration. A general methodology is proposed to determine this equivalent inertia for arbitrarily tapered cross-sections. By incorporating the influence of shear deflection, a comprehensive analytical framework is established for predicting the deflection of tapered BGCSWs. The accuracy of the proposed theoretical method is validated through experimental tests and finite element (FE) simulations.
