Journal of Studies in Civil Engineering

Assessment of Groundwater Quality for Drinking Purposes in Herat Province, Afghanistan: A Water Quality Index Approach

Kaywan Othman Ahmed — 2026-06-03

Understanding groundwater quality is essential for ensuring access to safe drinking water. This study investigates the suitability of groundwater for drinking purposes, employing the Water Quality Index (WQI) and analyzing various physicochemical parameters. The study was conducted from 2017 to 2021 in Herat, Afghanistan, a city facing numerous environmental challenges due to its arid climate and excessive groundwater extraction. To do this, the WQI was derived from data collected from 10 observation wells. A comprehensive analysis was performed on 13 physicochemical parameters, including pH, temperature, and various contaminants. The results showed that the groundwater WQI ranged from 26 to 131 across the region. The results of the physicochemical analysis showed that no groundwater in the Herat Basin exhibits excellent quality; 70% was classified as good, 20% as poor to very poor, and 10% as unsuitable for drinking, particularly in the Koshk Kohna district. The findings shed light on the overall quality of groundwater in the region, highlighting areas where water quality may pose risks to human health and emphasizing the importance of effective management strategies.

Performance Evaluation of Pervious Concrete Incorporating Dual-Sized Tire-Derived Aggregates: Mechanical, Thermal, and Permeability Perspectives

Mohammed Robitan Jalal — 2026-06-30

The incorporation of waste tire rubber into pervious concrete presents a sustainable solution for recycling end-of-life tires while improving stormwater management performance. This study investigates the novel use of dual-sized tire-derived aggregates (TDAs) as partial replacements for coarse aggregate in pervious concrete to evaluate their combined effects on mechanical behavior, permeability, density, and thermal durability. The results show a trade-off between strength and performance. At 28 days, compressive strength decreased from 19.85 MPa in the control mix to 7.02 MPa at 30% replacement, representing a reduction of approximately 64.6%, while splitting tensile strength declined from 4.10 MPa to 1.12 MPa and flexural strength from 2.02 MPa to 1.20 MPa. In contrast, permeability increased from 0.058 cm/s in the control mix to 0.102 cm/s at 30% rubber content, accompanied by a reduction in concrete density from 2062 kg/m³ to 1805 kg/m³, resulting in a lighter and more permeable material. Exposure to elevated temperatures up to 200°C further reduced compressive strength, particu-larly in rubber-modified mixtures. Overall, the results confirm a clear trade-off between strength and functionality. Rubberized pervious concrete with dual sized TDAs is suitable for non-structural uses where permeability and sustainability are prioritized overload capacity.

Structural Integrity Assessment of Plastic Sand Blocks under Thermal and Mechanical Stresses

Adutwum Marfo — 2026-06-30

This study presents a comprehensive evaluation of the fire performance of plastic-sand blocks (PSBs), addressing a key gap in understanding their safety under extreme conditions. Fire endurance, thermal insulation, and postfire hose-stream tests were conducted to assess their structural integrity and resistance to heat exposure. The equivalent thickness method was applied to determine the fire rating of the combustible PSBs and to benchmark their performance against conventional cement-sand blocks. In addition, both mechanical strength and thermal behavior were examined under fire conditions. The results reveal important performance trading-offs: compressive strength declined significantly from 7.8 MPa at ambient conditions to 3.2 MPa after fire exposure, and the thermal insulation capacity was lower than that of conventional blocks, indicating limitations in their structural fire performance. Empirical results demonstrated a stark contrast in fire resistance: the control cement specimen achieved a fire rating of 4 h 25 min, whereas the PSB failed rapidly at just 21 min. Furthermore, the plastic-sand composite significantly reduced the water absorption rate by 1.8% compared with the control, which showed a 4.2% increase. The postfire hose-stream test showed inward then outward wall deflection, highlighting key failure mechanisms and providing valuable data for assessing the structural safety of this alternative material.

Assessing Bus Service Quality in Dhaka City Using Structural Equation Modeling: A Comparison Between Users’ Perception and Expectation

Md. Nasif Hossain Imon — 2026-06-30

This study evaluates bus service quality in Dhaka City by comparing users’ perceptions and expectations using Structural Equation Modeling (SEM), addressing a key gap in quantitative urban transport assessment. Data were collected from 956 bus users across 11 major routes, covering 29 service-quality attributes related to comfort, safety, accessibility, and operations. Four SEM models were developed, with the final best-fit model (M4) comprising three latent variables: Physical Appearance, Safety and Security, and Service Features. Results reveal a pronounced gap between perceived and expected service quality. Approximately 42–50% of users rated seat comfort, riding safety, punctuality, and bus stop conditions as poor or very poor, whereas only 37–41% were satisfied with travel costs and lighting facilities. SEM results indicate that Service Features have the strongest influence on perceived convenience (standardized loading>0.90), followed by Physical Appearance. In contrast, Safety and Security exhibit weaker effects, indicating deficiencies in user protection and trust. Model fit indices confirm robustness (RMSEA = 0.080 for perception; 0.098 for expectation; SRMR<0.065). Overall, the findings highlight significant shortfalls between expected and experienced service quality, particularly in safety, driver quality, and reliability, providing quantitative evidence to guide targeted policy interventions improving Dhaka’s bus system.

A Physics-Informed Machine Learning Framework for Structural Damage Detection: Integrating Modal Analysis with SHAP-Based Feature Importance

Bibek Pokhrel — 2026-06-30

Structural health monitoring systems increasingly rely on machine learning, yet these models often function as black boxes that obscure the physical meaning of their predictions. This study addresses this gap by developing a novel Frequency Importance Weighted Damage Index (FIWDI) that bridges physics-based modal analysis with interpretable machine learning through SHAP value integration. The framework was validated using the Z-24 Bridge benchmark dataset, where we extracted modal frequencies from 45 test configurations spanning healthy and progressively damaged states. A CatBoost classifier achieved perfect classification accuracy (100%), with SHAP analysis revealing that the fourth vibration mode contributed 34.54% to damage detection—an unexpected finding that challenges conventional assumptions about lower-mode dominance. The FIWDI demonstrated superior sensitivity compared to traditional frequency-based indices. Statistical validation confirmed robustness across environmental variations. This work demonstrates that interpretable machine learning can enhance rather than replace physics-based understanding in structural engineering applications.

Flood Susceptibility Mapping in Erbil City Using Machine Learning Techniques

Kaifi Chomani — 2026-06-30

The objective of this research was to evaluate the performance of various machine learning approaches for identifying flood-risk areas in Erbil City, the Kurdistan Region of Iraq. In this study, three machine learning methods, Maximum Likelihood Classifier (MLC), Support Vector Machine (SVM), and Random Forest (RF), were compared to identify flood risk areas and assess their performance using historical flood data. Multiple factors such as Normalized Difference Vegetation Index (NDVI), aspect, Topographic Wetness Index (TWI), distance to roads, lithology, soil data, Normalized Difference Built-Up Index (NDBI), Land Use Land Cover (LULC), flow accumulation, rainfall, slope, Stream Power Index (SPI), drainage density, and elevation have been used to create susceptible flood areas. The results of different approaches for very high flood susceptibility were as follows: 22.7% (206.4 km²) for SVM, 26.5% (241.7 km²) for RF, and 9.1% (83.2 km²) for MLC. The Receiver Operating Characteristic – Area Under the Curve (ROC–AUC) accuracy assessments reported the following AUC values for flood susceptibility mapping: 87.3% for the MLC, 88.8% for RF, and 94.1% for SVM. The comparison analysis showed that SVM effectively maps flood susceptibility. This study offers insights into assessing flood hazards across different scales and data conditions, aiding better risk understanding and mitigation planning.

Hybrid Precast Systems Using UHPC and ECC: A Review of Mechanical and Durability Performance

Kummara Siva Prasad — 2026-06-30

Hybrid precast systems utilizing the synergistic properties of Ultra-High-Performance Concrete (UHPC) and Engineered Cementitious Composites (ECC) represent an advanced approach in civil engineering. UHPC provides exceptional compressive strength and very low permeability, while ECC offers high tensile ductility, strain-hardening behavior, and effective crack control. The strategic integration of these materials in precast elements, using UHPC in high-strength zones and ECC in critical connection regions, enhances structural performance and service life. This paper reviews the current state of research on the mechanical and durability performance of such hybrid systems, focusing on connection behavior, structural response under various loading conditions, and resistance to aggressive environments. The findings indicate that hybrid UHPC–ECC systems significantly improve ductility, energy dissipation capacity, crack control, and seismic performance, while reducing residual deformation. In addition, their combined properties enhance durability by limiting permeability, controlling micro-cracks, and improving resistance to chloride penetration, freeze–thaw cycles, and chemical attack. Overall, these systems demonstrate strong potential for developing resilient and long-lasting precast infrastructure, although challenges such as high material cost and the lack of standardized design guidelines remain.