This research examines the structural integrity of asphalt pavements in urban areas of Gulf Cooperation Council (GCC) cities—Riyadh, Dammam, and Dubai—through Falling Weight Deflectometer (FWD) testing. The study shows a general under-design of base layers with average back-calculated moduli ranging from 200–300 MPa, which is lower than the design standard of 400 MPa. A strong reverse correlation is found between Equivalent Single Axle Loads (ESALs) and asphalt modulus; with every increase of 1 million ESALs, there is a decrease of 10% in modulus. Moreover, ambient temperatures above 45 °C are responsible for a 15% reduction in asphalt stiffness, adding to fatigue and rutting hazards. For solution of these requirements, the paper suggests modified FWD thresholds within the climatic conditions of the Gulf: central deflection (D₀) below 120 µm and Surface Curvature Index (SCI) higher than 0.7. The approach covers a quantitative, non-destructive experimental framework by utilizing FWD surveys in shortlisted urban road corridors with a high volume of traffic. Data analysis entails back-calculation of layer moduli and statistical modeling to determine the effect of traffic loading and temperature fluctuations. The results highlight the need for region-specific pavement design and maintenance practices, incorporating FWD data into Pavement Management Systems (PMS) to improve infrastructure resilience and performance in the GCC region.

This study evaluates the compressive strength performance of Nipa Palm Fibre Reinforced Concrete (NPFRC) as a sustainable alternative for low- to medium-strength construction. Using Central Composite Design, the research examined how varying fibre content and length influence compressive strength. NPFRC compressive strength ranged from 9.17 to 21.96 MPa, compared to 26.12 MPa for conventional concrete. Higher fibre content and length generally reduced strength due to poor workability, compaction, and increased porosity. Fibre dosage had a more significant impact than fibre length. Interaction plots revealed that fibre content and length had interdependent, not additive, effects on strength. Response Surface Methodology (RSM) optimized the mix design, identifying 0.5% fibre content and 34.25 mm fibre length as ideal, yielding a predicted strength of 20.98 MPa with 92.30% desirability. A confirmatory test recorded 19.87 MPa, a 5.58% deviation from the prediction, within acceptable limits. Although the optimized compressive strength does not meet structural-grade standards (ASTM and EN 206), the results demonstrate NPFRC’s potential for non-load-bearing and light structural applications. The study highlights the importance of fibre treatment, optimal proportioning, and quality control, reinforcing NPFRC’s viability in eco-friendly construction where moderate strength and sustainability are prioritized.

Municipal Solid Waste Management (MSWM) remains a crucial environmental and public health concern in most of the fastest urbanizing areas, even in Nepal. An exploration of public opinion and economic feasibility of MSWM using sustainable strategies in Gaindakot Municipality, an expanding urban municipality of the Nawalparasi (East) District, is carried out. Employing a mixed-methods study design that comprises household surveys, interviews with stakeholders, field observation, and qualitative waste composition analysis, the current study presents an integrated analysis of the waste management system in the municipality. The findings indicate that despite 82% of the residents citing solid waste as the major problem, organized waste management practices are not consistently followed. Although 65% of the households utilize the municipal waste collection service, 16% still follow hazardous practices such as open dumping. This behavior pattern is also sustained by infrastructural deficits, such as the absence of engineered landfill facilities and composting facilities. Field surveys indicate that the city generates approximately 16.14 metric tons of waste daily, of which more than 60% is organic in composition, representing a gigantic potential for composting as well as energy production. The estimated daily revenue from recyclable waste material is NPR 63,760, i.e., it is economically worth implementing a circular model of waste management. There are, however, institutional problems like an absent master plan for integrated waste management, no technical capacity, and poor coordination among the stakeholders. In order to fill these ambiguities, the study makes the following practical suggestions: implementation of source segregation, facilitation of public-private partnerships, provision of economic incentives, and institutional capacity building through tailor-made training and policy support. The research provides policymakers, planners, and development agencies critical findings centered on the necessity for a socially inclusive, economically feasible, and environmentally sound MSWM system responsive to the condition of secondary cities in the Global South.

This paper addresses the concept of sustainable urban design by examining three prominent theories: New Urbanism, Compact City, and Green Urbanism. It analyzes the application of these theories through three significant urban projects: Celebration, Florida (New Urbanism), Hammarby Sjöstad (Compact City), and Atlanta BeltLine (Green Urbanism), based on six core principles of sustainable urban design, including mixed-use integration, sustainable mobility, social equity, environmental efficiency, quality of life, and urban resilience. The analysis reveals that the application of these principles faces considerable challenges. For instance, Celebration demonstrates success in improving public spaces and supporting sustainable mobility but fails to address social equity and environmental responsiveness. Hammarby Sjöstad, on the other hand, integrates urban density with sustainable systems, but economic challenges remain in fully implementing environmental solutions. Atlanta BeltLine offers a strong example of how green urbanism can repurpose old infrastructure into green networks, although social challenges, such as real estate inflation, threaten its social equity goals. The paper concludes with a discussion on the gap between theory and practice, highlighting how social and economic factors play a significant role in limiting the realization of sustainable urban design goals. Finally, it emphasizes the need for collaboration between urban planners, designers, policymakers, and local communities to develop flexible design solutions that balance environmental, social, and economic considerations. This research underscores the complexity of sustainable urban design, emphasizing the importance of adapting theories to real-world challenges in order to create cities that are resilient, inclusive, and sustainable for future generations.

This study examines the effect of Low-Density Polyethylene (LDPE) modification on the brittleness and stiffness of bituminous concrete mixtures and develops a regression model to predict the brittleness ratio (SR). Experimental results reveal that adding LDPE significantly increases stiffness, with brittleness ratios ranging from 1.998 to 3.169. While higher stiffness improves resistance to permanent deformation and rutting, brittleness ratios above the critical limit of 3.0 indicate a risk of premature cracking, especially at low temperatures. This highlights the need to optimize LDPE content to balance stiffness and ductility. A regression model was created to predict brittleness based on proportions of granite (Z₁), sand (Z₂), bitumen (Z₃), and LDPE (Z₄). The model showed good statistical validity, with an F-calculated value of 1.382 (below the critical 2.48 at 5% significance) and an R² of 70.38%, explaining a significant portion of brittleness variability. The Mean Absolute Percentage Deviation of 7.2% between predicted and experimental values confirms its accuracy within acceptable engineering limits. These findings suggest that LDPE-modified bituminous concrete offers improved mechanical performance but requires careful LDPE dosage control to avoid excessive brittleness. The validated model serves as a practical tool for designing durable, sustainable asphalt pavements balancing stiffness and flexibility across diverse environments.