Al-Rafidain Journal of Engineering Sciences

This review examined the effects of construction joints, particularly cold joints, on reinforced concrete beams' structural performance and integrity. Cold joints, which form when concrete is poured in stages rather than continuously, are often seen as weaknesses that can compromise the strength and durability of concrete structures. The review explored how cold joints impacted key properties like flexural strength, ductility, and energy dissipation capacity, drawing on numerous experimental studies. It was found that cold joints generally reduced the flexural strength of beams, with the extent of the reduction varying depending on the joint's location, orientation, and the time between pours. Additionally, factors like the type of reinforcement and joint angle played a significant role in mitigating the adverse effects of cold joints. The paper also discussed the importance of proper surface preparation and specific reinforcement techniques to enhance the performance of construction joints. The review of early and recent studies highlighted how cold joints affected tensile strength, shear, and bending capacities in reinforced concrete beams.

This research focuses on the evaluation of static buckling response of FG beams via Euler-Bernoulli and Timoshenko beam models. Loaded simply supported FG beams are loaded with axial compressive force and the properties of FG beam depend on the thickness and follow power-law distribution for all mechanical properties with constant Poisson’s ratio. The governing equations are obtained by minimizing the total potential energy and numerical solution is for the critical buckling load is obtained by using Navier-type approximation. The results show that as the slenderness ratio and power-law exponent increase, the critical buckling load reduces which is a sign of the mechanical change of the FG beam to resemble a uniform aluminum beam. The numerical findings are comparing with existing literature and have reasonable accuracy and usefulness for studying the structural behavior under different scenarios

Municipal solid waste (MSW) is currently one of the most significant environmental and public health concerns in rapidly growing cities like Kirkuk, Iraq. This study aims to determine residents' willingness to pay—financially and behaviorally—to improve MSW management practices through sustainable interventions. Based on a structured questionnaire completed by 329 residents, the study examines levels of awareness, acceptance of payment, behavioral willingness, and the influence of demographic and social determinants. The results reveal that most citizens, the sampling method used appears to be stratified sampling. The gender category includes 221 males and 108 females, showing that both genders are represented. The education levels are distributed among Bachelor’s degree holders (184), Master/PhD degree holders (122 in total, combining 121 and 1), and Baccalaureate graduates (23), covering various academic backgrounds. Age groups are also stratified, with participants aged 18-25 years (75), 26-35 years (103), 36-45 years (74), and above 45 years (77). Regarding employment, different job types are included such as employees (215), freelance workers (76), housewives (17), municipal employees in Kirkuk (9), students (8), and free business owners (4).This stratification helps ensure that the sample accurately reflects the population diversity of Kirkuk city in terms of gender, education, age, and occupation, making the findings more reliable and generalizable. A total of 75.4% of respondents showed a strong willingness to separate their waste, pay a small fee, and support waste reduction initiatives led by both government and community organizations. These results highlight the significant potential for participatory and decentralized municipal solid waste (MSW) management reforms in Kirkuk. The study suggests implementing incentive-based waste programs alongside focused awareness campaigns to boost public engagement in achieving sustainable urban sanitation.

This study focuses on the effectiveness of a laboratory-scale horizontal subsurface flow built wetland (HSSFCW) intended for phytoremediation of simulated residential wastewater using two ornamental plant species: Fittonia argyroneura and Syngonium podophyllum. The system was built using a transparent acrylic tank coated with coarse gravel, fine gravel, sand, and clay to mimic natural subsurface wetland conditions and encourage root-zone interaction. Over a 5-day period, experimental procedures were carried out to assess the removal of Total Dissolved Solids. Fittonia argyroneura consistently reduced TDS more effectively than Syngonium podophyllum, and its effectiveness remained reasonably steady over time. Syngonium podophyllum, on the other hand, revealed a considerable rise in TDS content with prolonged contact durations, which might be attributed to organic leaching or microbial imbalance. Statistical analysis revealed substantial (p < 0.05) differences between the two systems. These findings emphasize the significance of plant species selection in improving engineered wetland performance. The system's modular architecture and low-cost materials make it suitable for decentralized wastewater treatment, especially in small-scale or rural applications. Overall, Fittonia argyroneura showed increased flexibility and promise for application in sustainable phytoremediation systems aimed at nutrient-rich residential effluents.

This study examined the impact of corrosion on the ultimate strength of composite concrete beams and assessed the effectiveness of Glass Fiber Reinforced Polymer (GFRP) bars applied using the Near-Surface Mounted (NSM) technique. Five composite beams were cast and tested, each comprising a self-compacting concrete (SCC) web and a normal-strength concrete (NC) slab connected by vertical steel links. The primary variables were corrosion level and the location of GFRP strengthening. One specimen was used as a control, while the remaining four were exposed to either partial corrosion (50 mm into the slab) or full-depth corrosion across the entire cross-section. GFRP bars were applied through the NSM technique at two positions: within the slab region and in the tensile zone of the beam. Experimental results showed that corrosion significantly reduced load-carrying capacity, especially in fully corroded specimens, which failed earlier. However, NSM-GFRP bars enhanced the structural execution of corroded beams. Strengthening applied in the tensile zone yielded greater recovery in strength compared to slab-region application. The findings highlighted the importance of both corrosion severity and reinforcement placement in determining structural behavior. The study offered practical guidance for strengthening deteriorated composite beams using NSM GFRP systems.

In the resent decade, the composite materials became commonly used in different fields and sectors, specially in the airplane industry, military industry and spacecraft manufacturing. This widespread of using composites make scientists focusing their attention on studying the methods for improving the mechanical properties. In this research, the study concerned the growth and degradation in tensile and impact strength when curing the fiberglass with N. silica and used these fibers as a reinforcement material with epoxy in composite material. The methodology that adopted in research is preparation nanoparticle suspension that contains (1wt%, 3wt% and 5wt% SiO2 respectively) and H2O. The mixing of SiO2 and H2O done by using magnetic stirring and ultrasonic for disperse nano particles after that drying the fibers to remove the moisture, after that using the fibers as a reinforcement material with epoxy. The key findings were increasing the impact strength with percentage 43% as compared to control case (EP+2layers fiberglass) in the case of using samples fabricated of epoxy and 2 layers fiberglass immersed in (N.P.S) contains 1wt%SiO2 and 99wt% H2O. In general results of tensile decreased after curing the fibers with (N.P.S).

This study focuses on assessing the quality of groundwater wells in Iraq, analyzing the diffusion of high sulfate and chloride concentrations and their impacts on public health and the environment. The results highlight the necessary importance of these water sources in meeting the needs of rural areas, especially with increasing pressure on surface water resources. A comprehensive review of previous studies indicates frequent exceedances of these two ion concentrations above international standards World Health Organization (WHO) in several regions, calling for a more in-depth analysis of both natural (such as geochemical dissolution of sulfate-rich rocks) and human (such as unsustainable agricultural practices and sewage and industrial infiltration) sources of contamination. On the health front, the study highlights the clear link between the consumption of water contaminated with these ions and the spread of chronic diseases, such as kidney and gastrointestinal disorders, as well as their negative impacts on soil and infrastructure due to salt accumulation. The paper concludes with a call for strengthening water resource management policies and adopting innovative treatment solutions.

Structural behavior of ten RC slabs with dimensions of (900x900 mm), strengthened with CFRP and non-strengthened were evaluated experimentally, under concentrated load at the top fibers of their centers. All slabs were a simply supported of clear span (820x820 mm), which were made by normal and high strength self-compacting concrete; NSSCC, HSSCC. It was found that the tested slabs of HSSCC, e.g. from 30 to 60 MPa provide more resistance capacity of 18-23% than their counterparts made of NSSCC. Also, the latter increase is related to the decrease in the corresponding deflection under ultimate loads by (11-18%). In similar manner to the effect of HSSCC, the increase of reinforcement ratio results in the increase of resistance capacity by (21-27%). This leads to decrease in the corresponding deflection under the ultimate loads by (15-22%). In terms of the strengthened specimens with CFRP sheet, they also provide more resistance capacity by (25-33%) and a decrease in the corresponding deflection under ultimate loads by about (20-26%) as compared with non-strengthened specimens. Moreover, the obtained results indicated that the strengthened slabs along 50% of span length have a higher load capacity than those strengthened slabs along 25% of span length by (25%-33%). Further, the failure type of specimens was found to be in punching shear in all cases. However, the CFRP failures were found to be demolition, debonding, CFRP fracturing and peeling off.

This study investigates the synthesis and application of eco-friendly activated biochar derived from peach kernels (PK) for the removal of phenol from wastewater. The PK material was chemically activated using phosphoric acid and characterized using FTIR, SEM, BET, and XRD techniques. The activation process significantly enhanced the adsorbent’s surface area (from 0.54 to 928.47 m²/g) and porosity, as confirmed by BET analysis. Batch adsorption experiments revealed that phenol removal efficiency improved dramatically after activation, reaching over 99% under optimal conditions (pH 3–5, 200 rpm, 0.8 g dose, and 90–150 min contact time). Adsorption isotherm studies indicated that the Langmuir model best fit the experimental data (R² = 0.9973), suggesting monolayer adsorption. Kinetic analysis showed that the adsorption followed a pseudo-second-order model (R² = 0.999), indicating that chemisorption was the dominant mechanism. The findings highlight the potential of peach-kernel-derived activated biochar as an efficient and sustainable adsorbent for phenol removal in water treatment applications.

This review describes the new methods of wastewater treatment based on magnetic forces, showing their efficiency and effectiveness of pollutants removal. Different approaches are discussed such as magnetic separation, magnetically responsive materials, and magnetic field-assisted processes. It reviews their governing principles, functionality against various pollutants, and the benefits over conventional wastewater treatment processes. It also combines some of the problems and limitations hindering the implementation of the magnetic field technologies in practical applications. In addition, by merging the present research results and case studies, this review seeks to deliver aspects of how magnetic field-based approaches could be applied to improve wastewater treatment processes and also assist sustainable environmental management.