Browsing by Author "Perera, MAP"

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    item: Conference-Full-text
    Investigation on compressive strength of masonry blocks manufactured using crushed coconut shells
    (2013-11-26) Singhapura, SDKG; Perera, MAP; Chathushka, PGS; De Silva, GHMJS
    Coconut shells are produced in significant quantities in Sri Lanka as coconut tree has a large amount of usage in the country. Although coconut shell has different usages, considerably large amount of them remain in the environment as waste. Coconut shells dumped improperly to the environment provide breeding places for disease vectors such as rats and mosquitoes. Utilization of coconut shell as building material will be an important step to improve sustainability. In this study, an attempt was made to utilize Crushed Coconut Shell (CCS) in the manufacturing of masonry blocks as for the replacement of coarse aggregate (i.e., chips). Solid masonry blocks having the sizes of 360 mm ×100 mm ×170 mm were casted with the mix proportion of 1:5 Cement: Sand. Coconut shells were crushed, sieved and added to the mixture in different proportions to determine its optimum percentage of utilization. The blocks were experimented for 7, 14 and 28 day compressive strength. Compressive strength of crushed coconut shell based sand cement blocks with 20%, 25%, 30% (volume basis) of CCS have been examined, so as to investigate whether crushed coconut shell can be used as fully replacement of coarse aggregates and its optimum percentage. The structural performances of crushed coconut shell based sand cement blocks were compared with the same percentage of coarse aggregate sand cement blocks (i.e., control blocks). Water absorption capacity was investigated for this CCS based masonry blocks and was compared with conventional cement sand block with coarse aggregate.The optimum percentage of utilization of CCS was identified by considering maximum compressive strength that was obtained using laboratory experiments. It was found that the maximum compressive strength of CCS based cement sand block is achieved at 25% replacement level. The water absorption capacity was below the 12%, which is the requirement of maximum percentage of water absorption in masonry blocks.
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    item: Conference-Abstract
    Potential of applying Built-Operate Transfer (BOT) system for Sri Lankan highways- case study on Colombo-Katunayaka Expressway (CKE)
    (Department of Civil Engineering, University of Moratuwa., 2018-08) Perera, MAP; De Silva, D; Pasindu, HR
    The Sri Lankan transport network had a massive development during the last decade, experiencing highway infrastructure with the utilization of foreign concessions and local government funds of the country. The Road Development Authority holds the pioneer authority to operate and maintain the system periodically. The user benefits generated with these highways include travel time saving, developed infrastructure and living standards, also social benefits which are not counter measured quantitatively. As a developing country, the lack of financial stability for infrastructure of the government may lead to foreign loans and concessions. The concessions lead to rapid involvement in the fund involvement for mega infrastructure projects as the necessity and demand of the country. The Build - Operate and Transfer (BOT) concession model is becoming a major trend in the privatization of the infrastructure projects, the concession period and interest rate are the critical parameters for BOT contracts. A model for the evaluation of the potential of applying BOT system for the highways is developed in the study. The demand estimation, operation and maintenance cost, and toll income are used as the inputs for this model and financial viability is observed with different scenarios. The concession period, interest rates and optimality of the selection of BOT are decided with different criterions based on financial viability. As the Colombo-Katunayake Expressway (CKE), meets the highest demand for traffic in the Sri Lankan highway network, it is used to demonstrate the applicability of the proposed methodology. To minimize the ridership guarantee, the gap in-between the accumulated revenue and accumulated costs, optimum subsidy level is eliminated by differentiating acceptable criterions. Also, the BOT model is further expanded with risk assessment with the current trends, applying the suitability of applying to the expected income gain interconnecting with the Outer circular highway (OCH), Southern Expressway and ongoing Central Expressway to the CKE with different scenario analysis by minimizing the ridership guarantee.