Hot Mix Asphalts (HMA) may lose their stiffness over time due to traffic loads and environmental effects, leading to structural deformations. The Indirect Tensile Stiffness Modulus (ITSM) test, which is commonly used to determine such properties, requires coring and measurements conducted in laboratory environments using specialized equipment. Therefore, it is both costly and damaging to the pavement structure. This situation necessitates the investigation of faster, more economical, and non-destructive alternative methods. In this study, statistical and artificial intelligence-based relationships between ITSM and various non-destructive testing (NDT) methods (PQI, NDG, LWD, UPV, BP) were examined. The fieldwork was carried out on a 16 km section of the highway between Antalya and Burdur in Turkey. A total of 80 core samples were taken from 20 different locations at one-year intervals, and various non-destructive tests were also performed at the same points. The ITSM results obtained from the core samples were estimated using the non-destructive test data collected from the field. Both classical correlation analyses and Artificial Neural Network (ANN) models for multivariate prediction were employed in the analyses. The findings revealed that certain non-destructive test methods could estimate ITSM values with high accuracy. In particular, data obtained from LWD and UPV devices showed strong linear relationships with ITSM, yielding correlation coefficients above r>0.75 in single-variable correlation analyses. Among the ANN models developed in the study, the most successful model, M6, was structured using all non-destructive test data collectively. This model demonstrated a remarkable performance with an R² value of 91.18% for ITSM prediction. On the other hand, models based on individual test methods were observed to have relatively limited prediction success, generally ranging between 58% and 66%.
This study aims to quantify architectural design features and predict and explain their relationship with contract prices. This work focuses on the random forest algorithm, one of the machine learning algorithms. This algorithm is enhanced through parameter optimizations and compared with Shapley Additive Explanations (SHAP) to measure each architectural feature's contribution to the model's prediction. The combined evaluation of feature importance and SHAP significantly enhanced the model's interpretability. The results showed that the roof area and the number of doors had a significant impact on project costs among the building's architectural features. The performance evaluation metric outputs obtained, with R² at 0.8725, NSE at 0.8709, MAE at 0.6510, and RMSE at 0.9615, align with the developed prediction model. The study reveals the relationship between contract costs and their sub-variables using predictive models and explainable machine learning methods to build architectural features.
The significant amount of plastic waste generated globally has prompted the exploration of alternative uses for materials that create challenges for society. One such alternative is fiber-reinforced concrete (FRC) enhanced with recycled plastic fibers, which can improve the mechanical performance of concrete. Previous studies have mainly focused on the behavior of FRC under compressive loads, examining aspects such as workability, ultimate compressive strength, and modulus of elasticity, but they often lack a thorough analysis of various recycled plastic materials. This study provides a comprehensive analysis of the mechanical properties of FRC using different types of recycled plastic reinforcements, specifically PET rings, PET fibers, and plastic straws, at two different fiber dosages (5 and 10 kg/m³). A total of 33 specimens were tested under standard axial compression to assess workability, ultimate compressive strength, modulus of elasticity, Poisson's ratio, failure modes, and toughness. The performance of the recycled materials was compared to that of unreinforced concrete and FRC reinforced with industrial materials. The findings contribute to the advancement of green engineering practices across different construction sectors. Importantly, the study demonstrates that incorporating recycled plastic fibers into concrete yields mechanical properties comparable to those of FRC with industrial plastic reinforcements, especially at low fiber dosages.
This study investigates the effect of a novel supplementary cementitious material called kaolin-limestone blend (KLB) on the mechanical and fracture performance of high-strength self-compacting concrete of M60 grade. The KLB, composed of 66% calcined kaolin, 33% limestone powder, and 1% gypsum, was incorporated as a partial replacement of cement at 0%, 10%, 20%, 30%, 40%, and 50%. The experimental program evaluated impact energy, flexural strength, fracture energy, and critical stress intensity factor (KIC), along with brittleness through characteristic length. Microstructural investigations were conducted using a scanning electron microscope and X-ray diffraction analyses. The results showed that incorporating KLB effectively reduced the clinker factor, with KLB.5 exhibiting a 15-20% higher impact resistance than conventional SCC (CONV) at 28 days, 13.63-13.04% at 56 days, and 17.39-12.5% at 90 days. Flexural strength improved by 14.03% at 28 days, 12% at 56 days, and 10.24% at 90 days. Fracture energy peaked at KLB.4, surpassing CONV by 6.33%, 2.105%, and 2.41% at 28, 56, and 90 days, respectively. Whereas KLB.5 fell below CONV. This suggests that while the reactivity of the materials stabilizes at higher replacement levels, the filler and packing effects contribute to a dense and cohesive microstructure. At higher replacement levels, a reduction in KIC and characteristic length indicates increased brittleness, attributed to rapid crack propagation after peak load. However, prolonged curing partially mitigates this effect due to continued pozzolanic reactions. Overall, the KLB system demonstrated optimal performance at 50% replacement and shows strong potential for application in high-performance and sustainable concrete structures, particularly in high-rise buildings and precast elements where enhanced workability and strength are required.
Reactive powder concrete (RPC) is a high-performance concrete that contains very high amount of binder. With increase in the structural use of RPC, recognition and standardization of its mechanical and fracture behavior are needed. Although many studies have been conducted on material development, studies investigating bending behavior and fracture mechanism of reinforced RPC beams are limited. Acoustic emission (AE) technique can provide information on development and motion of cracks under load and significant amount of work has been conducted to characterize damage process of conventional (normal-strength) concrete. This study focuses on the research gaps regarding AE based fracture monitoring of large scale (125x250x1500 mm) reinforced RPC beams. Mechanical and acoustic emission tests were systematically and comprehensively evaluated in order to link AE indices to ductility and failure mode of structural beams incorporating three different steel reinforcement details. According to the findings, the instances where the average frequency decreases and the AE energy increases represent significant damage in the beams. The more ductile RPC beam generates a greater number of micro-cracks releasing low acoustic emission energy with low amplitude values. Even in the cases where the RPC beams showed a general shear-type failure, steel fibers retard the development of macro-cracks and thus, contribute to a more ductile behavior, which is justified by the resultant gradual increases in AE graphs. Long duration AE activities were observed when the fracture mechanism turned into a brittle performance. The critical points in the graphs representing the major changes in energy, average frequency, duration, and amplitude with elapsed time are following each other.
Unsaturated soil mechanics is a crucial area of geotechnical engineering that has gained increasing importance in recent years. However, despite its relevance, no standard guidelines have yet been implemented to study unsaturated behaviour in laboratories. This gap limits professionals’ ability to address practical challenges in arid and tropical regions, particularly in problematic soils under shallow foundations, as well as in collapsible and expansive soils. In addition, critical geotechnical structures such as earth dams, slopes, and pavements require expertise in this field. In this context, the main objective of this study was to analyse the influence of varying suction conditions on the shear strength of a problematic clayey silt soil, which exhibits a macrostructure and microstructure with highly compressible characteristics and sensitivity to moisture variations. The research was conducted following ASTM standards for physical and compressibility characterisation. Specific methods included the consolidated drained triaxial compression test with controlled suction (CID-CA-CS) and the unconsolidated undrained (UU) triaxial test for unsaturated mechanical characterisation. The PRISMA model was also applied to define the strength parameters of saturated soil and estimate the linear failure envelope of unsaturated soil. The key findings include an increase in shear strength to 102.8, 128.8, and 157.4 kPa for matric suction values of 81.3, 160.2, and 246.9 kPa, respectively. This research concludes that suction plays a fundamental role in soil strength and stiffness. Additionally, when suction is lost, the soil undergoes significant deformations under loading. Finally, the reconstituted state of the material and unconsolidated undrained conditions are not representative to evaluate its unsaturated soil behaviour.
The digitalization of the AEC sector, while steadily progressing, has been largely driven by technological adoption rather than by a transformation of its organizational structures. Within construction 5.0, the AEC organizations have not been investigated in depth. For this reason, exploratory research is currently underway to examine the mutual impact between digital transformation and organizational structures, but it has not yet been fully developed. For this reason, this research examined a joint conceptual model between digital transformation and organizational structures. Based on a previous conceptual model, a panel of industry and academic experts will conduct an assessment. This assessment was conducted using the Delphi method, bringing together 40 academic experts and industry-leading professionals to provide a holistic view of digital transformation, both theoretical and practical. The experts' responses were analyzed using statistical methods, including Kendall's concordance, level of importance, consensus, and Mann-Whitney analysis. The main findings from this study show a consensus among the experts in the conceptual model, having as the most relevant variables Transformational Leadership, Data Integration and Analytics, Knowledge Management, and Integrated Organizational Innovation (IOI) are critical in a joint digital-organizational implementation, this conceptual model provides a vision to construction companies to improve their productivity and achieve their goals through digital transformation and organizational redesign in the context of construction 5.0.
This study employs both experimental and numerical methods to investigate the blast resistance of ceramic fiber-reinforced geopolymer concrete (CFGC), a cement-free material often referred to as green concrete due to its environmentally friendly nature compared to Portland cement concrete (PCC). Geopolymer concrete specimens, formulated with ground granulated blast furnace slag, silica fume, and varying proportions of ceramic fibers, were subjected to blast tests using 50, 100, 150, 200, and 250 grams of trinitroglycerin (TNG). A standard PCC specimen was utilized as a control. The results demonstrate that the incorporation of 10% ceramic fibers significantly enhances the blast resistance of the geopolymer concrete, reducing crater diameters by up to 20% compared to conventional PCC. Furthermore, the finite element model developed in ANSYS Workbench exhibits a strong correlation with the experimental data, validating the predictive capability of the numerical simulations. Overall, this research highlights the immense potential of CFGC as a sustainable, highly durable alternative for structures exposed to blast loads.
Reinforced concrete (RC) structural elements could be exposed to impact loads due to several reasons in their expected service lives. However, impact loading is often overlooked in the design phase of RC elements, unlike quasi-static or other dynamic loads, such as earthquake and wind loads. Because sudden impact loads can cause significant damage to structural systems within a short period, they may result in substantial damage to a structural element or the collapse of the entire structure. Structural engineers tend to investigate the effects of impact loads both experimentally and numerically. This study aims to determine the dynamic responses and failure modes of prestressed concrete slabs. For this purpose, an improved finite element analysis that incorporates prestress effect and strain-rate effects for concrete and steel materials has been developed to investigate the impact behavior of prestressed concrete slabs. To validate the finite element analysis, maximum impact force and displacement values, as well as the residual displacements and energy absorption capacities of the two specimens, were compared with the experimental results reported in a previous study. Subsequently, a parametric study was conducted using different analysis inputs, and the results were evaluated at the end.
Glass fibre reinforced polymer (GFRP) rebar is an alternative material to traditional rebar. GFRP rebar exhibits superior ductility and corrosion resistance compared to steel reinforcement. This study investigated the flexural behaviour of eight GFRP-and steel-reinforced concrete beams with dimensions of 150mm x 200mm x 2500mm, subjected to two-point loading. The flexural behaviour of RC beams reinforced with High-Strength Concrete (HSC) was investigated. The control and optimum average cube compressive strengths are 81.64 MPa and 83.42 MPa, respectively. Both steel and GFRP RC beams were examined, with the addition of 0.6% steel fibre. The main objectives of this study encompassed thespecimens' load-carrying capacity, failure mode, ductility, stiffness, and energy absorption capacity. Notably, GFRP RC beams demonstrated superior load-carrying capacity and ductility compared to steel RC beams. Additionally, the mid-span deflection of the RC beams was evaluated using two codes: ACI 440.1R and CSA S806. Furthermore, proposed a method to predict mid-span deflection, and our experimental results closely aligned with the predictions.
This paper presents a laboratory study of the effect of naturals (hemp fibers) and synthetics fibers (glass fibers) on the mechanical behavior of sandy soil (natural Chlef sand). A series of shear direct tests were carried out on medium dense (RD= 50%) and dense (RD= 80%) Chlef samples sand with different naturals and synthetics content fibers ranging from 0, 0.25, 0.5, 0.75 and 1% and under three normal stress of 50, 100 and 200 kPa. The test results show that the addition of fibers has a significant effect on the shear strength of the sand-fiber mixture, however, this shear strength increases with the increase of the fibers content, the normal stress applied and the relative density until up an optimal fibers content of 0.5% for the glass fibers and 0.75% for the hemp fibres. Beyond these optimal fibres content, the shear strength decreases. The internal friction angle and the cohesion are significantly influenced by the fibres content.
In recent decades, the production of waste engine oil (WEO) and waste cooking oil (WCO) has risen, primarily attributed to shifts in human lifestyles and advancements within the automotive industry. In light of growing environmental concerns and efforts to enhance asphalt mixtures, researchers have investigated integrating these waste materials into traditional bitumen formulations. Thus, this study examines the laboratory investigation of varying proportions of WCO and WEO on the rejuvenation effect, including chemical, rheological, performance grading (PG), and resistance to permanent deformation of asphalt. A total of 7 blends were prepared, consisting of the base bitumen and different proportions of WEO (7%, 10%, and 13%) and WCO (3%, 6%, and 9%) by weight of bitumen. The rheological properties of high-temperature PG bitumen and the rutting depth of asphalt mixtures were evaluated using the Dynamic Shear Rheometer and Cooper Wheel Tracker Test. The research outcomes confirm that incorporating an appropriate dosage of WCO and WEO meets the criteria for conventional bitumen physical properties. Furthermore, the lower dosage of the WCO blend exhibited adequate tensile properties, thermal susceptibility, PG, and resistance to permanent deformation compared to WEO blends. Meanwhile, introducing WCO and WEO does not trigger additional chemical changes. However, excessive incorporation of waste oil can result in an undesirable reduction in the bitumen phase angle, thereby prolonging the construction timeframe. Therefore, based on rigorous statistical analyses, it is recommended that WCO and WEO be incorporated at dosages of 3% and 7%, respectively. This study highlights the potential of recycling WEO and WCO by incorporating them into bitumen for use in the asphalt pavement sector, thereby expanding the utilization of waste oils.
Geotechnical engineering frequently encounters soils exhibiting insufficient mechanical strength or undesirable hydraulic properties, necessitating the implementation of soil improvement techniques. In the contemporary context of escalating global energy demands and rapid population growth, the selection of stabilization materials must rigorously prioritize sustainability, environmental compatibility, and cost-effectiveness. Furthermore, the expansion of energy infrastructure, often involving near-surface heat transfer mechanisms, requires a comprehensive understanding of soil behavior under elevated thermal regimes. This study investigates the potential of dried Zostera marina (seaweed) biomass as a novel, sustainable, and low-cost alternative additive for soil stabilization. Historically recognized for its thermal insulation capabilities in cold climates, Zostera marina represents a readily available waste product of marine origin. The research focused on evaluating the thermo-hydraulic conductivity performance of mixtures formulated by incorporating Zostera marina into a base matrix of zeolite and bentonite. Hydraulic conductivity tests were systematically conducted under two distinct thermal conditions: ambient laboratory temperature (RT) and an elevated temperature of 40 degrees C, allowing for the isolation of additive and thermal influences on permeability. The experimental results demonstrate a critical dual behavior. At ambient temperature, the inclusion of Zostera marina effectively reduced the hydraulic conductivity of the mixtures. However, under the 40 degrees C thermal regime, a discernible increase in permeability was recorded, a finding consistent with established literature concerning the temperature-dependent hydro-mechanical response of organic-rich or clay-based matrices. These findings highlight the ne-cessity of considering service temperature when developing sustainable stabilization techniques utilizing marine biomass additives.
Rapid urbanization and the global climate crisis have intensified the challenges of sustainable transportation and urban drainage. Inadequate storm water infrastructure in many developing cities often results in severe water accumulation on road surfaces, increasing the risk of aquaplaning and freeze-related accidents. This study investigates fiber-reinforced permeable concrete (FRPC) as an alternative rigid pavement material capable of enhancing both drainage capacity and structural performance. Experimental mixtures incorporating polypropylene fibers at 0.5-1.0 kg/m3 were evaluated in terms of mechanical strength, durability, and permeability. The results demonstrated that the inclusion of fibers increased compressive strength by up to 77%, splitting tensile strength by 65%, and flexural strength by 40%, while abrasion resistance was significantly improved. However, permeability decreased slightly with fiber addition, and freeze-thaw resistance remained limited. Microstructural analyses confirmed that fiber bridging contributed to improved crack control and residual strength. The findings suggest that FRPC can effectively mitigate surface water accumulation and improve road safety, particularly in light-traffic areas, pedestrian and bicycle paths, and parking facilities. Overall, unlike previous studies, it explicitly addresses the simultaneous optimization of drainage capacity and mechanical performance, providing a novel integrated approach to FRPC as a sustainable pavement solution. Polypropylene fiber reinforcement provides a practical and sustainable approach to balancing permeability with mechanical durability in pavement design tailored to urban drainage needs.
Pavement surface deformations are related to design deficits, or problems of stability of the materials pavement. To have a sustainable material that ensures a long enough life for the pavement, several research have been developed. This work focuses on the effect of crumb rubber on the static creep behavior of asphalt mixtures, aiming to improve their mechanical performances and rutting resistance on the one hand, and to contribute to environmental sustainability on the other. Crumb rubber was incorporated into asphalt mixtures at varying percentages (0.25%, 0.5%, and 0.75%) using a dry process. Samples of asphalt mixture compacted with gyratory compactor and Marshall Method were tested at two temperature levels, (20 degrees C and 60 degrees). The modification of asphalt, temperature and mode of compaction are parameters that influence creep properties and rutting resistance. During the static creep test, total deformation (epsilon Tot), initial deformation (epsilon In), permanent deformation (epsilon Per), creep stiffness and Creep compliance were recorded. Results showed that the presence of crumb rubber at low content in asphalt mixture improve their performances, while at high content of crumb rubber, a decrease in the performance of the asphalt mixtures was observed. Also, the properties of static creep recorded during the creep test are better for the specimens compacted with Gyratory compactor comparing with those compacted with Marshall Method. Aiming to predict creep stiffness and creep compliance as a function of crumb rubber content and Axial micro deformation, a model was developed using adaptive neuro-fuzzy inference system (ANFIS) approach. The results demonstrate that the developed ANFIS models provide accurate predictions with strong agreement with experimental results.
To contribute to sustainable environmental protection studies, the durability and strength properties of geopolymer, which is known as more eco-friendly than ordinary Portland cement, have been a phenomenon among many searchers in recent years. In this study, the durability properties of geopolymer mortars containing C Class fly ash (FA) added with silica fume (SF) were investigated under the influence of sodium sulfate (NS) and magnesium sulfate (MS). Within the scope of the study, FA geopolymer mortar samples were produced with fixed ratios of potassium hydroxide (KOH) and sodium hydroxide (NaOH) and 3 different ratios of silica fume additive (5%, 10%, 15%). The samples were kept at room temperature for up to 28 days after production. Their physic-mechanical properties were examined. The samples were placed in NS and MS solution. Length and weight changes, flexural and compressive strengths of the samples were measured for 30 days, 90 days and 180 days. As a result of the experiments, it was observed that the samples produced by activating with NaOH didn't lose strength at a high ratio, while the compressive strength (CS) of the samples produced by activating with KOH and under the influence of sulfate increased on the 30th day. It was determined that the CS of the samples under the influence of NS reached 75.14 MPa at 30 curing days and the samples under the influence of MS reached 64.31 MPa. In general, the produced samples were found to be resistant to sulfate effects.
In this study, the influence of creep was comprehensively investigated for both prismatic and non-prismatic reinforced concrete beams using finite element analysis, while taking a prior experimental study into consideration. The research was conducted in two stages. In the first stage, the reliability and accuracy of the finite element modeling approach were assessed, and it was concluded that this method is suitable and effective for examining the creep behavior of reinforced concrete beams. In the second stage of the research, a comprehensive parametric study was conducted to determine the effect of each parameter (such as load values, load types, compressive strength, tensile reinforcement ratio, water-cement ratio, aggregate-cement ratio, relative humidity, and shear span-to-depth ratio) on the creep behavior of both prismatic and non-prismatic beams. The results indicate that creep deformation is more pronounced in non-prismatic beams, where the inclination angle notably influences the structural response. Consequently, the load-to-capacity ratios were adjusted to account for the increased creep effects.
In this study, the earthquake performance evaluation of a 4-storey residential building was investigated. The residential building was designed according to studies on T & uuml;rkiye's building stock and the Turkish Earthquake Code 1997 (TEC-1997). The building was considered as an existing building, and its earthquake performance was evaluated according to the Turkish Earthquake Code 2007 (TEC-2007) and the Turkish Earthquake Code 2018 (TEC-2018). Pushover (POA) and nonlinear time history (NTHA) analyses, which are given in TEC-2007 and TEC-2018, were used in evaluating the earthquake performance of the building. The main purpose of the study is to compare both earthquake codes and analysis methods. The study is valuable and original because it uses a building that represents T & uuml;rkiye's low-rise building stock and conducts a detailed performance evaluation according to different codes and methods. The performance of the building was evaluated under the design earthquake. The analyses of the structural system were accomplished by using SAP2000 software, incorporating inelastic material behavior for concrete and steel. The software of RESPONSE2000 was used for sectional analyses of the structural system and the moment-curvature curves. Ground motion records were taken from the PEER Ground Motion Database, and the records were edited with the help of SEISMOSIGNAL software. The numerical results were given in tables and figures comparatively and discussed. It was determined that TEC-2018 is safer than TEC-2007 in terms of determining ground motion records and damage limits of the structural system elements. Moreover, the results showed that when POA and NTHA were compared, although NTHA provided more realistic results, POA can also provide acceptable results.
This research uses numerical analysis to evaluate the ultimate load-carrying capacity and deflection behaviour of reinforced concrete (RC) 90 and laced reinforced concrete (LRC) 45 beams under high reverse cyclic loading conditions. Due to practical limitations, this field has not been explored experimentally. The beams were modelled using ANSYS employing sophisticated nonlinear material models, such as the Mene-trey-William model for concrete to take cyclic loading effects into account and a tangent modulus approach for reinforcing steel to predict post-yield behaviour. The analysis revealed that LRC 45 outperformed RC 90, exhibiting 30% less deformation and 18% higher maximum principal stress at 500 kN, demonstrating its enhanced stiffness and structural integrity. Additionally, LRC 45 exhibited the highest ultimate load (137 kN) and lowest deformation (12.86 mm) among the tested beams, with an average ductility factor of 2.08, making it the most suitable for dynamic and seismic applications. The systematic assessment of ductility, energy absorption, and failure mechanisms under a well-designed cyclic loading procedure and the verification of numerical findings against experimental data represent the uniqueness. The study's innovative use of cyclic and monotonic loading methods in conjunction with thorough stress-strain analysis offers insightful information on the robustness of reinforcement setups, allowing more precise forecasts of beam performance in dynamic real-world situations.
In this study, commercially available cattle bone ash (CBA) was utilized as a partial cement replacement to evaluate its near-term and practical applicability in mortar production. CBA was incorporated into mortar by replacing Portland cement in 5% increments, up to a maximum of 30%. The research assessed both the fresh properties (such as table flow) and the hardened properties (including density, water absorption, compressive strength, drying shrinkage, and ultrasonic pulse velocity) of the mortar. The findings showed that while increasing CBA replacement rates generally led to a decline in mortar properties, replacements up to 10% had negligible effects. Specifically, mortar with a 10% CBA replacement exhibited a density only 0.1% lower than that of standard mortar, a 7-day compressive strength 2.3% higher, and a 28-day compressive strength 3.8% lower. Furthermore, even with 30% of Portland cement replaced by CBA, the mortar still met industry standards for both 7-day and 28-day compressive strengths, making it suitable for applications in brick and flooring. These findings highlight the feasibility of using CBA as a supplementary cementitious material and provide practical guidance for its rapid field application.
