Institutional-Repository, University of Moratuwa
Welcome to the University of Moratuwa Digital Repository, which houses postgraduate theses and dissertations, research articles presented at conferences by faculties and departments, university-published journal articles and research publications authored by academic staff. This online repository stores, preserves and distributes the University's scholarly work. This service allows University members to share their research with a larger audience.
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Recent Submissions
item: Thesis-Abstract
Lean integrated carbon financing model for construction industry
(2026) Wijayawardena, DSI; Ranadewa, T
The construction industry accounts for over one-third of global greenhouse gas emissions, urging the need for sustainable construction methods. However, almost all sustainable construction methods struggle to balance financial returns with environmental benefits. Carbon financing offers a promising solution by providing financial incentives for reducing carbon emissions, making it an environmentally and economically friendly option. Despite the benefits, practical applications of carbon financing in construction are challenged by many inefficiencies, redundancies and non-value adding activities. Lean principles directly address these challenges by emphasising value maximisation for stakeholders and encouraging a culture of continuous improvement. Hence, this study aims to develop a lean-integrated carbon financing model for the construction industry. A mixed-method approach was employed, combining a questionnaire to quantify the significance of financial impact for sustainable construction, with two rounds of expert interviews to explore the sector-specific carbon financing factors and lean integration. Quantitative data were collected from 388 respondents selected through snowball sampling and analysed using random forest regression. The qualitative data were collected from 18 experts selected through purposive sampling and code-based content analysis was employed to analyse the data. The study identified that financial challenges can influence and be influenced by sustainable construction challenges. Furthermore, carbon financing was defined based on the five notions and 4 primary carbon financing methods were identifed and described. The findings also identified 22 benefits and 19 challenges specifically associated with the implementation of carbon financing in the construction sector. The study has developed a comprehensive definition of carbon financing and identified that the best carbon financing method for construction industry would be combining carbon financing methods. A lean-integrated carbon financing model was developed to identify the most suitable carbon financing method for construction projects after validating it through focus group interviews. The research concludes that integrating lean principles with carbon financing can significantly reduce carbon financing challenges and improve adoption in construction. The study contributes to the academic discourse by deriving a definition for carbon financing and identifying sector-specific carbon financing factors, including benefits, challenges, and methods. Application of random forest models for sustainable construction research and potential use of lean principles for carbon financing are also key contributions of the study.
item: Thesis-Abstract
Analysis of the effect of heat column generation on energy performance of split AC units in high-rise residential buildings
(2026) Harithkhan, VM; Nissanka, NAID; Manthilake , MMID
In recent high-rise residential building constructions, air-cooled split-type air conditioners are popular due to their cost-effectiveness and installation flexibility. However, placing outdoor units in restricted building re-entrants creates heat columns along the height of the building. This phenomenon adversely affects energy efficiency and contributes significantly to the overall power consumption of the A/C units. I recent years, the escalating use of air conditioners due to global warming highlights the substantial energy dedicated to space cooling. Hence, improving air conditioning efficiency is vital in managing end-user electricity consumption. This research examines split air conditioning performance in a tropical high-rise residential building, focusing on heat column generation in re-entrants. The study assesses system efficiency under different loads and outdoor temperatures. A numerical framework was developed to optimize condenser layouts, allowing simulation of various scenarios. By analyzing outdoor wind conditions, individual usage, and room cooling loads, the research aims to predict the impact of heat columns generation on Split A/C performances in high rise residential buildings. The study reveals that elevated ambient temperatures in re-entrants significantly degrade performance due to heat column effects. CFD simulations demonstrated that condenser placement and re-entrant geometry critically influence temperature distribution, with upper-floor units experiencing severe accumulation, causing COP reduction up to 62% and elevating consumption by 75%. Simulations showed that under no-wind conditions, locating units 1.5 m from the exterior wall minimized heat column buildup, while 2.0 m proved optimal at 2 m/s outdoor wind conditions. Introducing a perforated slab improved thermal management, lowering peak temperatures from 64°C to 59.5°C at no-wind conditions. The findings underscore strategic importance in optimum layout of outdoor units in re-entrants to enhance efficiency and reduce costs, providing insights for architects and engineers. This study contributes insights into factors influencing heat column strength and emphasizes the mathematical framework for optimizing condenser arrangements.
item: Thesis-Abstract
Bond characteristics of carbon fiber reinforced polymer strengthened concrete member exposed to acidic solution
(2023) Thushanthan, K; Gamage, JCPH
Deterioration of construction materials due to aggressive environments is becoming a serious issue nowadays. Concrete is a widely used construction materials however, due to its alkaline nature, it is highly susceptible to acidic corrosion. Therefore, the concrete structures lose the aesthetic appearance and become structurally unsafe even before it’s intended service life. In order to rehabilitate these deteriorated structures fiber composites were introduced in the civil engineering industry. Several types of fiber composites are available for the civil engineering application, however, due to the superior engineering properties Carbon Fiber composites are commonly used to strengthen buildings which may experience aggressive environments. Carbon Fiber Reinforced Polymer (CFRP) composites consist of carbon fibers which are relatively immune to the aggressive environmental conditions and epoxy resin matrix which is highly susceptible to environmental degradation. Extensive researches were conducted all around the world to investigate structural strengthening and load transfer mechanisms of CFRP strengthened system however, environmental degradation of these systems were studied comprehensively. Especially, very minimum research studies were conducted to investigate the degradation of CFRP to concrete strengthened system in acidic environment.
This study aims to address the lacuna regarding the deterioration behaviour of CFRP to concrete strengthened system in acidic environmental conditions. Extensive literature review was conducted to identify available research studies and limitations in CFRP to concrete strengthened system in aggressive environmental conditions. At the beginning, a case study was conducted at Awissawela wastewater treatment, which was renovated from a near collapse condition by CFRP composite. Later experimental studies were conducted to study the degradation behaviour of CFRP, concrete and CFRP-Concrete interface under various acidic condition. These acidic conditions were simulated in order to achieve actual conditions identified in several locations. Series of accelerated environmental exposure were conducted and several tests were carried out.
Finally, the obtained results were statistically analysed and conclusions were presented.
item: Article-Full-text
Why Traffic Signals Fail in Sri Lanka: Reviewing the Realities of Heterogeneous Traffic Dynamics
(The Institution of Engineers Sri Lanka) Salawavidana, SAST; Pasindu, HR; Bandara, JMSJ; Munasinghe, R
Traffic signal design in developing countries frequently underperforms due to the direct application of classical models—Webster's delay formula, HCM, ARR123, and ORN13— developed for homogeneous, lane-disciplined traffic conditions. Sri Lankan intersections exhibit fundamentally different characteristics: heterogeneous vehicle streams comprising motorcycles, threewheelers, non-motorized vehicles, and pedestrians operating without strict lane discipline under geometric constraints. This systematic review synthesizes empirical evidence explaining why conventional signal design methods fail in such contexts. Following PRISMA principles, 138 records were screened, yielding 41 high-quality references spanning foundational theory, classical assumptions, regional adaptations, and Sri Lankan empirical data. The review demonstrates that local intersections systematically violate foundational assumptions regarding lane usage, headway uniformity, start-up behavior, and pedestrian compliance. Observed saturation flows reach 2574 pcu/h/lane—substantially exceeding HCM benchmarks—while behaviors such as motorcycle seepage, lateral filtering, initial surge, and dynamic clustering create discharge patterns that static PCU values cannot capture. A mathematical framework is presented mapping these deviations to quantifiable variables: lateral efficiency, surge discharge dynamics, dynamic vehicle equivalence, headway expansion, and geometric constraints affecting intersection capacity. The paper concludes by proposing context-sensitive design pathways incorporating dynamic PCU factors, behavioral modeling, and simulation-based calibration using SIDRA and SUMO to support locally relevant signal control methodologies..
item: Article-Full-text
Mineralogical Evolution and Geo-mechanical Characterization of Weathering Profiles Along the Central Expressway (CEP 3), Sri Lanka
(The Institution of Engineers Sri Lanka) Sanjeewa, KWD; Nawagamuwa, UP; Abeysinghe, AMKB
This research investigates the mineralogical and geo-mechanical factors influencing slope stability along Section 3 of the Central Expressway Project (CEP 3), Sri Lanka. Through a combination of borehole logging, petrographic analysis, and X-ray diffraction (XRD), a comprehensive weathering profile was established. Results delineate a transition from stable, fresh metamorphic gneissic rocks to highly unstable residual soils (SM and ML types). Petrographic data reveal the progressive alteration of primary minerals, specifically Feldspar, Biotite, and Hornblende, into secondary Clay phases. XRD analysis identified the presence of Smectite and Kaolinite, with the former presenting significant risks for moisture-induced volume changes and rotational slides in high-cut sections. The study concludes that the thickness and stability of the residual mantle are directly governed by the modal mineralogy of the metamorphic parent rock, providing a critical framework for geotechnical risk mitigation in hilly terrains