This research aimed to evaluate the impact of using brick waste powder (BWP) and varying lengths of polyester fibers (PFs) on the performance properties of asphalt concrete (AC) mixtures. BWP was utilized as a replacement for traditional limestone powder (LS) filler, while PFs of three lengths (3 mm, 8 mm, and 15 mm) were introduced. The study employed the response surface methodology (RSM) for experimental design and analysis of variance (ANOVA) to identify the influence of BWP and PF on the selected performance indicators. These indicators included bulk density, air voids, voids in the mineral aggregate, voids filled with asphalt, Marshall stability, Marshall flow, Marshall quotient, indirect tensile strength, wet tensile strength, and the tensile strength ratio. The findings demonstrated that BWP improved moisture resistance and the mechanical performance of AC mixes. Moreover, incorporating PF alongside BWP further enhanced these properties, resulting in superior overall performance. Using multi-objective optimization through RSM-based empirical models, the study identified the optimal PF length of 5 mm in combination with BWP for achieving the best AC properties. Validation experiments confirmed the accuracy of the predicted results, with an error margin of less than 8%. The study emphasizes the intriguing prospect of BWP and PF as sustainable alternatives for improving the durability, mechanical characteristics, and cost-efficiency of asphalt pavements.

The main objective of this work is to study the performance of prestressing steel (PS) bars as reinforcements in the reinforced concrete (RC) elements strengthened by the near-surface mounted method (NSM). The work includes two parts. In the first part, direct pull-out tests are performed in order to study the bond performance between PS reinforcement and concrete. The influences of groove sizes and PS surface conditions (smooth and sand coated) are evaluated. The results show that the sand coated PS (PS-Sc) reinforcement has the best adhesion behavior compared with the smooth bar, and its pull-out force is increased by 48%. For this reason, the PS-Sc bars are used in the second part of this work as NSM reinforcement to strengthen RC beams subjected to bending forces. Then, four-point bending tests are carried out to understand the flexural behavior of strengthened RC beams with PS-Sc reinforcements of different lengths and ratios. The obtained results demonstrate that the use of NSM-PS-Sc bars strengthening technique leads to important enhancement in the load carrying capacity of the RC beams. The first crack load and ultimate load of the strengthened RC beams attain 71.41 and 65.67%, respectively, which are higher than those of the control beam. Furthermore, the experimental values show a good agreement with the analytical values in both the ultimate deflection and the ultimate load. This proves that the NSM-PS-Sc bars studied in this work are promising reinforcement of the RC beams.

This paper presents an experimental and numerical study for the effect of the cavity on the behaviour of a strip footing positioned on a reinforced sand slope. This study used a new type of geosynthetics called fiber carbon and fiber glass. These components have the potential to isolate the soil inside the geosynthetic and prevent shears stress mobilization. The investigation aimed to determine the effect of cavity depth (h) and the number of reinforcing layers (N) on the bearing capacity and settlement characteristics of footing, empirically for investigating the effect of cavity on the bearing capacity, some parameters were assumed constant in all tests, for example, relative density, a distance of the footing from the slope edge, and length between layers of reinforcement. The variable parameters are the distance between footings and centre of cavity and the number of reinforcing layers. The results show that the settlement behaviour of footing adjacent to a soil slope is significantly affected by h and N. It is observed that qu, which represents the ultimate bearing capacity, improves with an increase in N. The influence of the cavity appeared insignificant when it was positioned at a depth equal to twice the width of footing.

Experimental tests on confined concrete specimens are essential to characterize the mechanisms activated under varying degrees of confinement. Such characterization is critical for understanding how full, partial, and non-uniform wrapping configurations influence strength and ductility enhancements. This study investigates the compressive behavior of concrete cylinders (160 mm × 320 mm) confined using full, partial, and non-uniform carbon fiber-reinforced polymers (CFRP) configurations. In the first phase, all wrapping schemes were applied with equivalent quantities of CFRP, enabling a direct performance comparison under material parity. The results indicate that non-uniform confinement (NUC) achieved approximately 15% higher axial strength than full confinement (FC2) using the same amount of CFRP. In the second phase, the NUC configuration was tested with 25% less CFRP material, yet the reduction in strength was limited to about 3%, demonstrating its superior efficiency. A new predictive model was developed to estimate peak axial stress and strain in CFRP-confined concrete cylinders. Compared to existing models, the proposed model demonstrated greater predictive accuracy (R² = 0.98 for stress and 0.91 for strain) and reduced error metrics (RMSE and scatter index). ANOVA confirmed the statistical significance of the model’s predictions (p < 0.00001 for stress, p = 0.002 for strain). These findings highlight the performance advantages and material efficiency of non-uniform CFRP confinement and support the utility of the proposed model as a practical design tool for developing advanced confinement strategies in structural engineering.

This study investigates the prediction of immediate settlement (Uz) in soft clay improved with Deep Soil Mixing (DSM) columns under heavy aircraft loading. Two key design parameters were considered: column spacing (2.25 m to 3.75 m) and column length (6 m to 20 m), with both rectangular and triangular arrangements analyzed. The datasets obtained from numerical simulations were modeled using Response Surface Methodology (RSM) and Artificial Neural Networks (ANN), with model calibration and validation performed through k-fold cross-validation. The statistical analysis revealed that both approaches achieved excellent predictive capability, with R² values exceeding 0.999. For the rectangular arrangement, RSM yielded slightly lower errors (RMSE = 0.0636 cm, MAE = 0.0553 cm) compared to ANN (RMSE = 0.0828 cm, MAE = 0.0682 cm), suggesting that a second-order polynomial approximation can effectively describe the settlement response in this configuration. Conversely, for the triangular arrangement, ANN clearly outperformed RSM, reducing RMSE from 0.0725 cm to 0.0265 cm and MAE from 0.0615 cm to 0.0111 cm, thereby capturing the nonlinear stress redistribution associated with isotropic column layouts more effectively. Observed–predicted plots confirmed the high predictive accuracy of both methods, with ANN showing superior generalization in triangular grids. Overall, the findings highlight that RSM remains a robust and computationally efficient tool for rectangular layouts with relatively linear responses. In contrast, ANN provides enhanced accuracy for triangular configurations where nonlinear interactions dominate, making it particularly suitable for DSM design optimization in airport pavement foundations.

Improving saline soils’ properties by incorporating limes is a practical technique, generally due to cation exchange, pozzolanic reaction, and carbonation. This study explores how soil salinity, measured by electrical conductivity, affects untreated and lime-treated saline soils. An Algerian sebkha soil (from Ain M’lila) with an original high salinity (ECe3 = 23.2 dS.m⁻¹) was used. The same soil was washed to create medium (ECe2 = 8.3 dS.m⁻¹) and low (ECe1 = 2.32 dS.m⁻¹) salinity soil samples. The results of this study indicate that salinity influenced the shape of the particle size distribution curve, particularly in the silt range. Salinity also had a significant effect on carbonate content (CaCO₃) and unconfined compressive strength (UCS). For the untreated soil, when salinity decreased, the UCS and CaCO₃ content increased. However, when salinity decreased for the treated soil, the UCS increased, while the CaCO₃ content decreased. X-ray diffraction (XRD) analysis of untreated soils showed halite (NaCl) disappearance and gypsum (CaSO₄ 2H₂O) reduction with decreasing salinity in ECe1. In treated soil at ECe3, these mineral phases remained constant. While XRD detected no new cementitious phases in treated ECe3 or ECe1 samples, thermogravimetric analysis confirmed the presence of portlandite in both. As Ain M’lila sebkha is a chloride–sulfate soil, the dissolution of the halite and gypsum phases released more Cl⁻ and SO₄²⁻ ions into the interstitial solution. In a low fraction of clay, these ions obstructed and slowed the pozzolanic reaction in the ECe3 soil. Identifying the season when this type of soil has lower salinity can be beneficial for treatment from a technical, economic, and environmental point of view.