2A12 aluminum alloy is widely used for tail pipe suspension attachment tools due to its low density, high strength and good drillability. However, it is prone to corrosion in harsh drilling environments—specifically at high temperatures (220°C), high salinity (30% salt), and strong alkalinity (pH 14)—leading to tool failure and compromising the safe operation of oil and gas wells. To address this issue, a composite coating was developed using supersonic flame spraying of WC and a sealing layer of Si-Ni applied via magnetron sputtering. The coating’s performance was evaluated through full immersion corrosion tests and quartz sand experiments, as well as characterized using Scanning Electron microscope, Energy Dispersive Spectrometer and X-Ray Diffraction techniques. The results show that the composite coating exhibits excellent corrosion and scour resistance. After 48 hours of corrosion exposure, the weight gain was reduced from 32.25% to 4.1%, and the aluminum alloy substrate remained uncorroded. During high-speed sand scouring (17.5 m/s), the coating was only partially detached without furrow formation, and the scour rate dropped from 24.74 mg/(cm2*h) to 0.544 mg/(cm2*h). The coating maintained full coverage of the substrate. SEM analysis revealed a WC coating thickness of 30-50 mm. While the rel-atively large WC particle size (average 12.58 mm) created surface cavities and pores, the subsequent Si-Ni sealing formed dense spherical clusters that reduced the surface porosity from 21.78% to 5.63%. In summary, the WC-Si-Ni composite coating effectively mitigates corrosion and scouring issues in 2A12 aluminum alloy under extreme conditions, thereby enhancing tool reliability in oil and gas well operations.
This experimental study investigates the compressive behavior of cylindrical concrete specimens internally confined with Polyethylene Fiber Geogrid Mesh (PFGM). A total of 60 specimens were prepared using two concrete cover thicknesses (10 and 20 mm), three PFGM confinement levels (1, 1.5 and 2 layers), and three curing ages (7, 14 and 28 days). The main scientific contribution is the experimental quantification of how an embedded polymeric geogrid modifies the post peak response of concrete, especially ductility, energy absorption and crack propagation, while causing only limited changes in compressive strength. The results indicate that PFGM confinement changes compressive strength by approximately +/-5% on average, but markedly improves deformation capacity. Energy absorption increased by about 90%, ductility by about 50%, and the strain corresponding to maximum stress by about 30%. The embedded mesh also delayed brittle failure by limiting surface crack propagation toward the concrete core and reducing concrete fragmentation after peak stress. These findings show that PFGM can serve as an effective secondary reinforcement for improving ductility, crack control and post peak integrity in concrete members.
Stainless steel reinforcement has attracted growing interest in structural engineering due to its superior durability, yet existing reviews remain limited and fail to integrate material behavior, structural performance, numerical modeling, and emerging data-driven approaches. This review addresses that gap by providing an integrated evaluation of experimental findings, analytical insights, and finite element modeling (FEM) strategies related to stainless steel rebars. Its contribution lies in offering a comparative evaluation of stainless-steel grades, a critical examination of their structural response under varied loading and environmental conditions, a consolidated assessment of constitutive and modeling practices in FEM, and an exploration of recent machine-learning applications for property prediction and behavioral modeling. The review further highlights limitations in current testing methods and design provisions, underscoring the need for improved constitutive models capable of representing nonlinear, anisotropic, and path-dependent behavior. Finally, it identifies future directions centered on hybrid experimental-numerical methods, high-performance computing, and data-driven frameworks to enhance the accuracy and reliability of stainless steel reinforced concrete design.
This study presents a comprehensive statistical evaluation of the compressive strength (CS) of recycled aggregate concrete (RAC) using predictive modeling. A dataset of 262 samples from various RAC mixtures was analyzed to assess the influence of key variables, including cement, water, natural and recycled aggregates, sand, and superplasticizer. Descriptive statistics, correlation, and sensitivity analyses revealed that cement content is the most influential parameter, followed by sand and water content, while recycled coarse aggregates had a negligible effect on CS. Several predictive models were developed, including Linear Regression (LR), Non-linear Regression (NLR), Quadratic Regression (QI and QII), and Cubic Regression. Model performance was evaluated using R², RMSE, and MAE. The results indicate that the non-linear regression model provides the most reliable predictions, achieving balanced performance on both the training (R² = 0.75, RMSE = 4.73 MPa) and testing (R² = 0.67, RMSE = 5.23 MPa) datasets. Although RAC offers sustainability benefits through waste reduction, its application remains challenging due to the limited mechanical contribution of recycled aggregates. The findings highlight the importance of optimized mix design and careful material selection for effective implementation of RAC in construction.
This study presents an assessment of the seismic vulnerability of a road bridge, designed before the introduction of the RPOA-2008, representative of a bridge type that is potentially vulnerable and widespread in the Algerian road network. The seismic vulnerability of the bridge was assessed using analytical fragility curves. The curves were developed using incremental dynamic analysis (IDA) and assuming a log-normal cumulative distribution. The curves were generated for the key components of the bridge and then for the entire bridge by adopting a series system approach. The results revealed that the fragility of the bridge as a whole is governed primarily by the fragility of the columns of its central pier. Compared to the seismic demands of RPOA-2008, the damage state of the bridge would be light to moderate, except in extreme seismic situations where it would be significant.
