Champika Ellawala Kankanamge

This study examines how economic crisis-driven water tariff reforms aimed at cost recovery distributed the financial burden across households with heterogeneous consumption patterns. Using 43 months of data from over 20,000 urban households in Galle (January 2021–July 2024), tariff-related consumption adjustments and revenue impacts were analyzed across three clusters identified through pre-reform patterns. The clusters operated at mean monthly consumption levels of 11.29 ± 5.46, 20.89 ± 6.31, and 33.25 ± 11.46 units (1 unit = 1 m3). Revenue share of low-consumption households (40% of consumers, 25% of consumption) increased from 13.8 to 21.8%; Moderate-consumption households (47% of consumers, 52% of consumption) increased from 45.7 to 49.4%; High-consumption households (13% of consumers, 23% of consumption) declined from 40.6 to 28.7% with minimal changes in consumption share. This divergence stemmed from tariff structure design rather than behavioral adjustment. Fixed service charges increased 300–500%, while volumetric rate progression weakened in upper blocks (400% increases for 0–15 units versus 70–80% for 26–40 units). Although reforms achieved cost recovery goals, they failed the equity principles by imposing disproportionate burdens on low-consumption households.

Material scarcity and environmental concerns have strengthened interest in waste glass utilization in concrete, offering enhanced mechanical properties through pozzolanic reactions. However, the high reactivity of glass waste presents significant durability challenges through the Akali-Silica Reaction (ASR). This comprehensive review systematically analyzes ASR development mechanisms in glass-mixed concrete, evaluating the influence of particle size, glass content, and colour on ASR susceptibility. Critical findings reveal that particle size emerges as the primary ASR susceptibility factor, with fine particles (1 mm) demonstrating high reactivity. Glass colour significantly influences ASR potential, with chromium-rich green and brown glasses showing superior resistance compared to clear glass due to modified chemical composition. Increased glass content correlates with enhanced ASR risk, though fine glass particles ( fly ash (30%) > Ground Granulated Blast Furnace Slag (GGBFS) (60%), effectively limiting alkalinity and controlling moisture availability. Chemical inhibitors using lithium/aluminum compounds modify ASR gel composition, while mechanical reinforcement through steel fibers and rubber particles reduces post-ASR internal stresses. Despite promising mitigation approaches, significant knowledge gaps persist in long-term performance data, scale-dependent behavior understanding, and standardized testing protocols. Future research must prioritize predictive model development, protocol standardization, and comprehensive field validation studies. Successful glass waste integration requires systematic research, bridging laboratory findings with field performance requirements, while ensuring structural durability and safety.

Slurry trench cutoff walls have been used since the 1970s and have come into widespread usage since the 1980s as a component in overall remedial systems to control groundwater flow, particularly for seepage mitigation in earthen dams. Different types of slurry trench cutoff walls, such as Soil-Bentonite (SB), Cement-Bentonite (CB) and Soil-Cement-Bentonite (SCB) are used to control seepage. Although numerous methods have been adopted, there is still a question about the most effective method to control seepage. As such, this research study reviews the possibility of using Soil-Cement-Bentonite (SCB) cutoff walls for seepage control in earthen dams. This paper discusses the available construction procedures and required engineering characteristics of SCB backfill such as gradation, unconfined compressive strength, permeability and durability. SCB backfill is composed of soil, cement, and bentonite. Most literature indicates that cement and bentonite contents directly affect the strength and permeability characteristics of SCB cutoff walls. SCB cutoff walls become more economical as trench excavated soil is used as the backfill material. It was noted that in order to get the maximum benefit of SCB, fines content of backfill material should be 10%-30%. The addition of cement and bentonite to the SCB mix delivers moderate strength and lower permeability in the cutoff wall. Cement enhances strength, while bentonite reduces permeability. The basic design strength of SCB cutoff walls is 100 kPa, which can be increased up to 1000 kPa by varying the cement and bentonite content. In terms of permeability, values of less than 1 × 10−6 cm/s can be achieved in SCB cutoff walls. However, there are many incompatibilities between the cement and bentonite ratio suggested after conducting laboratory experiments and those applied in the field. Therefore, it is necessary to investigate the optimum cement and bentonite contents to deliver the most economical and best-performing SCB cutoff wall. Additionally, it is essential to study the influence of alternative wetting-drying condition on the performance of SCB cutoff walls.

The use of personal protective equipment (PPE) is compulsory when accessing public places due to the ongoing COVID-19 pandemic in many countries. Facemasks are the most common PPE used, however, some people use face shields and gloves. Frequent hand sanitizing is also recommended aiming to control the spread of the disease. All these activities generate a large amount of plastic waste daily. In Sri Lanka, it is estimated that 12 million facemasks are used daily, while 0.22 million gloves and 0.29 million face shields are used. Out of 12 million facemasks, 10 million are surgical or N95 masks. In addition, 0.79 million sanitizer bottles are used in a day, leaving empty plastic bottles. The most common method of disposing of facemasks in Sri Lanka is open burning by the users at their homes (55%). The rate of burning is comparatively low for other PPE. Although nearly 30% of people handover used facemasks to the municipal solid waste collection, there are no special precautions taken for separate collection and safe disposal. Guidelines are in place for handling healthcare waste generated in households under self-quarantine, but they are not applied for PPE waste generated in other households. Major drawbacks in PPE waste management is identified and mitigation measures were proposed. The estimate of waste plastics generated due to PPE use is 88.5 tonnes per day in the country. Energy recovery via pyrolysis may be a viable alternative to landfilling and affordable for developing countries.