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Engineer : Journal of the Institution of Engineers, Sri Lanka
Number of Followers: 0  

  This is an Open Access Journal Open Access journal
ISSN (Print) 1800-1122
Published by Sri Lanka Journals Online Homepage  [48 journals]
  • Geotechnical Engineering Properties of Fly Ash and Bottom Ash: Use as
           Civil Engineering Construction Material

    • Abstract: Norochcholai coal power plant is the largest coal power plant in Sri Lanka and during the combustion of coalit annually generates about 250,000 metric tons of coal ash which consists of fly ash (FA) and bottom ash (BA). Almost all the generated ash is disposed into ash dumps except a small quantity of FA (30%) that is effectively utilized. Therefore, use of coal ash for construction purposes will offer a sustainable solution for reducing its by-products and overcoming the scarcity of raw materials required for construction work. The main aim of this research was therefore to determine the geotechnical engineering properties of FA and BA to find out the feasibility of using them as light weight embankment or backfill material. A series of laboratory experiments were conducted on FA, BA and FA-BA co-mixed samples to determine their particle size distribution, specific gravity, index properties, compaction characteristics, shear strength parameters and California bearing ratio (CBR). The experimental results reveal that the particle size of coal ash (FA and BA) is predominantly silt sized while containing some sand-sized fractions as well. This coal ash has a low maximum dry density (MDD) and a high optimum moisture content (OMC) compared to typical granular soils used in embankments. In addition, this ash has a higher friction angle and higher cohesion than most types of construction fills. Thus, both FA and BA can be used as light weight embankment or back fill material in civil engineering construction work. Published on 2018-01-31 00:00:00
  • From the Editor Vol. 51 (1)

    • Abstract: No abstract available Published on 2018-01-31 00:00:00
  • Investigating the Teleconnection between Warm ENSO Phases and Seasonal
           Rainfall over Kotmale Catchment in Sri Lanka

    • Abstract: Seasonal rainfall over Kotmale reservoir is changing at an alarming rate due to atmospheric oscillations taking place over Sri Lanka. Therefore, this study focused on the teleconnection between warm El-Nino Southern Oscillation (ENSO) phases and rainfall over the Kotmale catchment. Daily rainfall data obtained from 11 meteorological stations were used to identify the behaviour of the annual rainfall climatologies of the catchment. Inflow data of the Kotmale reservoir obtained for the period 1984 to 2012 were analysed to understand reservoir inflow trends. Sea surface temperatures were obtained from Japan Meteorological Agency to determine the warm El- Nino Southern Oscillation phase. The rainfall at the stations and the inflow to the reservoir have declined over the period selected. However, the rate of decrease has varied from station to station. Seasonal rainfall at all the stations considered between December and September showed a negative correlation with the mean sea surface temperature of the Nino 3 region. Warm El-Nino Southern Oscillation caused below average seasonal rainfall over the catchment between December and September. The northeast and southwest monsoon rainfall over the catchment has weakened because of warm El-Nino Southern Oscillation phase in the Nino 3 region. However, the effect has got reduced with the onset of monsoons. Published on 2018-01-31 00:00:00
  • Three - dimensional Numerical Simulation and Validation of Load-settlement
           Behaviour of a Pile Group under Compressive Loading

    • Abstract: Settlement of pile foundation is one of the controlling pile design parameters and its numerical simulation is one of the techniques widely used to predict the settlement behaviour of piles. This study was on the settlement behaviour of a pile group located in silty-sand deposits using the finite element (FE) approach which is based on the static pile load test. Three different types of analyses were investigated: (1) a linear elastic (LE) analysis in which the soil was assumed to be linear elastic, (2) a complete nonlinear analysis in which the soil adjacent to the pile shaft as well as the soil between the piles were modelled using the Mohr Coulomb (MC) or hardening soil (HS) model, and (3) a combined analysis in which the soil close to the pile shaft was modelled using the HS model while the soil in the remaining area was modelled using the LE or MC model. Numerical results obtained for the load-settlement behaviour of the pile group were validated using the popular RATZ analytical approach. The results of the FE analysis suggest that incorporating a nonlinear zone of soil close to the pile shaft as an interface and leaving the soil beyond this zone as linear elastic give a more reasonable estimation and a much better prediction of the pile group settlement. It is also suggested that for a typical pile group, a nonlinear interface of thickness equal to the pile diameter and extending from the pile shaft to the edge of the zone would be sufficient to capture the load transfer mechanism. The group settlement ratio predicted in this study is in good agreement with the findings made in the previous studies. Published on 2018-01-31 00:00:00
  • Service Road Construction Using Cement Stabilized MSW at the Karadiyana
           Open Dumpsite, Sri Lanka

    • Abstract: Dumping of municipal solid waste (MSW) on low-land is a waste disposal method used by most of the municipal councils in Sri Lanka. Rapid economic development, population growth, inadequate infrastructure and land scarcity have made it necessary to introduce improvements to MSW dump sites in the country. Setting up of new dumping sites is now being discouraged due to public pressure and steps are underway to optimize the existing dump yards. In this regard, the heights of the fills will have to be increased after the locations have been completely filled up with MSW although owing to poor style of dumping and very low bearing capacity of the fill, most of these locations will not be able to accommodate any further filling up. The situation at the dump site at Karadiyana is also same. Thus, a decision has been taken to have cement stabilized service roads as access roads to this dump site. Several samples were collected along the proposed service road stretch and basic studies on them were undertaken using Proctor compaction and California bearing ratio (CBR) tests to classify and investigate their present capacities. The values obtained are far below the values stipulated by ICTAD. After the MSW samples were stabilized with different cement proportions, it was observed that compared to the CBR of unimproved MSW, the CBR of cement stabilized MSW is significantly higher and that it exceeds the minimum value specified by ICTAD. Published on 2018-01-31 00:00:00
  • Cinnamon Firewood as a Biofuel for Electricity Generation

    • Abstract: Biomass based electricity generation is now a well-established concept and in Sri Lanka, gliricidia has been accepted as the most suitable biofuel. Considering this and the fertilizer displacement benefits, the Government of Sri Lanka has given prominence for cultivating gliricidia on a large scale by declaring it as the fourth plantation crop. The objective of this paper is to discuss the use of cinnamon firewood as a biofuel for electricity generation. Thus, analysing cinnamon wood’s heat characteristics, examining its availability and assessing its potentiality for electricity generation are matters of paramount importance. Cinnamon wood is the residue left from peeling the cinnamon bark. The villagers in cinnamon growing areas were the first to identify the superior heat generating properties of cinnamon wood as compared to other types of firewood. However, its effectiveness as a biofuel for electricity generation could be best assessed by comparing its heat characteristics and other properties with those of gliricidia. Cinnamon grows in most parts of the country and cinnamon wood is available year-round as a byproduct. The process is sustainable, and the 32,345ha of cinnamon plantations presently available have the potential to add at least 80GWh annually to the national grid. Hence, there may not be a need to devote land purely for cultivation of biofuels. Published on 2018-01-31 00:00:00
  • Mitigation of Hospital Acquired Infections in Developing Countries through
           the Provision of a Better IAQ

    • Abstract: Indoor Air Quality (IAQ) determines the functionality and economics of a building. Thus, healthcare facilities are under pressure to maintain good IAQ as many people are at risk because of the infectious diseases that can spread through air quite easily. When infections caught by hospitalized patients are not controlled, Hospital Acquired Infections (HAIs) could develop. HAIs relate to those infections that are not present at the time of admission of a patient but which develop during the course of his/her stay at hospital. HAIs directly affect patients, their caretakers and employees. Hence, the healthcare sector is highly concerned about IAQ since airborne microorganisms present in indoor air can cause HAIs. In this study, a qualitative approach was used with semistructured interviews and a documentary review to collect data from three identified cases. Resulting findings were validated by four experts. Initially, the importance of IAQ in the healthcare sector was identified through semi-structured interviews. Sources affecting IAQ such as human activities, equipment etc., were recognized from the literature survey and validated through semi-structured interviews. Consequently, the impact and causes of HAIs like inadequate ventilation, poor hand hygiene, poor housekeeping etc., were investigated and a framework to assist in mitigating HAIs by improving IAQ was proposed. Published on 2018-01-31 00:00:00
  • A Study on Reinforced Concrete Columns Partially Confined with Carbon
           Fibre Reinforced Polymer (CFRP)

    • Abstract: Although the use of carbon fibre reinforced polymer (CFRP) materials is considered as a very effective retrofitting technique for reinforced concrete columns, still it is the identification of cost reduction strategies that draws most of the attention since the use of CFRP materials is considered as more expensive than any other retrofitting method. Providing partial confinement in place of full confinement which is the current practice may be a viable option that allows for considerable cost savings while maintaining the required structural capacity. Although CFRP technology has been in use for several decades, some countries still do not have adequate technical know-how to use this technique effectively. As there are several design guidelines available globally, it is quite unclear which design guideline will provide an economical design while maintaining the required factor of safety. This paper presents an experimental study conducted using 17 specimens to investigate the strength increments due to external CFRP confinement of reinforced and unreinforced concrete columns. Reinforced concrete columns were provided with both full and partial confinement to study their strength and ductility increments. The volumetric ratio of CFRP was kept constant for partially confined columns to study the effect of the jacket arrangement pattern. The experimental failure loads obtained were reviewed against the theoretical values calculated using ACI and fib guidelines, to investigate the overall safety factors available when using each design guideline. The experimental results showed considerable strength and ductility increments in all of the fully and partially confined specimens. Although the volumetric ratio of CFRP was kept same for all partially confined columns, it was observed that depending on the jacket location, the strength and ductility increments would vary. It was also observed that both design guidelines give for fully confined reinforced concrete columns, a factor of safety exceeding 1.5. Published on 2017-10-31 00:00:00
  • Impact of Cost Control Techniques on Cost Overruns in Construction

    • Abstract: Construction industry plays an important role in the development of a country. The success of any project will depends on how that project can achieve its objectives in terms of cost, quality and duration. In order to achieve success in a project, it would be essential to plan that project well and have a proper monitoring mechanism in place. Cost overrun is a major problem encountered by many contractors as it makes the profit of a project less secure for the contractor in addition to causing many other problems to all the parties involved. Good cost control techniques would be essential to solve those problems. Thus, it is important to identify cost controlling techniques and their impact on cost overruns. This study was done using a questionnaire survey conducted among C1-C5 grade contractors. The data collected were analysed by converting them into quantitative values using percentage analysis and weighted score analysis. The results indicate the cost controlling practices that are in frequent use and their importance in minimizing the cost overruns in order to reduce over budget and overheads while securing anticipated profits. Finally, it is suggested that CIDA (ICTAD) should encourage contractors to use cost controlling techniques, by conducting training programs, awareness programs, etc. It is also suggested to make the use of some of ICTAD documents mandatory. Published on 2017-10-31 00:00:00
  • From the Editor Vol.50 (4)

    • Abstract: No abstarct available Published on 2017-10-31 00:00:00
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