Browsing by Author "Meegahage, JN"

Now showing 1 - 9 of 9

item: Conference-Abstract
Challenges of wearing course mix design for Hambanthota International Airport
(Department of Civil Engineering, University of Moratuwa., 2012-07) Meegahage, JN; Mampearachchi, WK; Pasindu, HR
Hambanthota international Airport (HIA) is a major ongoing development project in Sri Lanka. Since an Airport is a very important location for a country, durability and long term performance with least maintenance is fully ensured in the selection of material to the design and the construction methods in airport runways. In HIA, wearing course of runway has been decided to construct using Polymer Modified Bitumen (PMB) which is currently unfamiliar to Sri Lankan Highway industry. The modified binder to be used in the construction is PG 76-22 SBS modified binder. Further more the specified aggregate gradation for the design is coarser than the ones currently using in Sri Lankan highway industry. So it’s a challenging task to prepare a mix design for the wearing course. Polymer modified binder properties are different from conventional bitumen with high resistance to deformation at elevated temperatures and cracking at low temperatures. Some additional tests are included for the SBS modified binder to ensure its quality such as elastic recovery test and separation tendency test which are currently unfamiliar. Establishment of Viscosity ranges of the modified binder for compaction and mixing temperatures was a challenging task since the polymer modified binder behavior is non Newtonian.. In HIA the aggregate gradation selected for the mix design is coarse than the normally used aggregate gradation for asphalt wearing course. The maximum aggregate size is 31.5mm and the minimum size is 0.063mm. The aggregate was blended to avoid the maximum density line of Thompson and fuller curve and the Superpave restricted area to meet the design criteria. The mix design for asphalt concrete was done using the marshal mix design. The asphalt mixing and compactions were conducted at different temperatures to obtain the optimum temperature for mixing and compactions. The gradation has considerable effect on satisfying the specification limits of air voids (VTM) and void in mineral aggregate (VMA). Effect of gradation, mixing and compaction temperatures were studied in the mix design using PMB binders.
item: Conference-Abstract
Evaluation of temperature susceptibility measures in penetration grade bitumen used in Sri Lanka
(Department of Civil Engineering, University of Moratuwa., 2013-07) Meegahage, JN; Mampearachchi, WK; Pasindu, HR
In the recent years Sri Lanka has experienced a massive evocation in highway construction than any other period in the history. This leads to enhance the quality of ride and minimize the cost and time incur with transportation industry. Most of these highways are being constructed with Hot Mix Asphalt (HMA) where bitumen is a major constitution. The increase in demand for bitumen has lead the way to increase bitumen production and import significant amount of bitumen. In order to have good quality long lasting pavements one should ensure the usage of bitumen with desired properties. In Sri Lanka 60/70 penetration grade bitumen is used for HMA. One of the major problems in penetration grade bitumen is the absence of temperature susceptibility measures within the grading system. In this study the bitumen used in Sri Lankan roads are evaluated using several temperature susceptibility measures. They are Penetration Index (PI), Viscosity Temperature Susceptibility (VTS) and Pen-Vis Number (PVN). Bitumen samples collected from various highway projects around the country was evaluated using the above temperature susceptibility measures. The result of these measures has been analyzed for the correlation and with the limits specified in literature. It was found that there no good correlation between penetration and softening point of bitumen samples. About 50% of the samples tested showed lower penetration than the required penetration and similar behavior was obtained with their consistency. Penetration Index related to softening point showed that many samples tested were in highly temperature susceptibility region. VTS values for the test samples were scattered throughout and out of the VTS limits. PVN values obtained for the test samples were scattered closely at the temperature susceptibility region. Using the findings of the literature the behavior of PVN was approximated to PI which shows further evidence of temperature susceptibility nature of Sri Lankan bitumen. The results of temperature susceptibility measures of PI, PVN and VTS highly vary among the samples.
item: Conference-Abstract
Indoor thermal performance of green roof in a tropical climate
(2016-10-12) Dareeju, BSSS; Meegahage, JN; Halwatura, RU
The concept of Sustainable building development has been promoted to overcome the issues occurring due to the energy crisis, environment impacts and rapid urbanization. Minimization of energy usage for achieving a comfortable indoor thermal environment in a building is one of the key elements of sustainable development. However, it is very important to assess the performance of buildings with sustainable elements in tropical countries, where warm humid climatic conditions prevail. As a result, green roof is proposed as a sustainable element for buildings in tropical climatic conditions and its indoor thermal performance was determined experimentally using small scale models. Using those experimental results and literature, large scale buildings were modelled to simulate the indoor thermal performance of sloping traditional roofs, reinforced flat concrete slabs and green roofs. The results have proved that green roofs provide acceptable indoor thermal performance with respect to the other traditional roofs. It was found that the green roofs act as resistive and capacitive insulators, which result in more indoor thermal comfort to the occupants while re-establishing the relationship between human and environment, which have been destroyed due to the rapid urbanization. In addition to the indoor thermal performance green roofs also provide cyclone resistance, aesthetics and higher robustness to the building.
item: Conference-Extended-Abstract
Indoor thermal performance of turf roof slabs
(2010) Halvvatura, RU; Dareeju, BSSS; Deshappriya, KA; Meegahage, JN
In the past few decades the scientists had focus their attention more on sustainable development because of the energy crisis, while has reached to an alarming level. Energy requirement of urbanized arrears is rising at an increasing rate. Since people are more concern about thermal comfort, it can further accelerated with expected global climatic changes. The impact of the environment due to urbanization lead us way towards sustainable development. The traditional construction methods are replacing with new innovations and trends shows that the traditional sloping roof are replaced by flat slabs, since it can create another usable space at the roof level and also a green environment at the roof level. Buildings coupled with greenery will be an ideal solution for many environmental and social issues face by the occupants mainly in urban areas. The life cycle performance can be used to access its long term performance of the grass roof slabs and can be used to compare the new system with existing arrangements. It was shown that green roof slabs could have a desirable behavior with respect to life cycle performance in addition to providing other benefits such as cyclone resistance, aesthetics, use as an outdoor living space, and higher robustness to the building.
item: Conference-Full-text
Influence of grass cover on flat reinforced concrete slabs in a tropical climate
(2013-11-27) Dareeju, BSSS; Meegahage, JN; Halwatura, RU
Reinforced concrete slab is a better alternative to regain the land due to the buildings because available land is insufficient for usage with respect to the rate of urbanization. However, the reinforced concrete roof slabs do not perform in acceptable level in tropical countries with warm humid climate condition and tend to act as heated bodies which emit long wave radiation to the occupants. As a solution, a green roof is proposed and its thermal performance was determined experimentally using small scale models. Using experimental results, large scale building models were developed to simulate the indoor thermal performance of green roofs and it is shown that the green roof provide satisfactory indoor thermal performance while providing many other benefits such as enhancing aesthetic and regaining lost land for the building.
item: Article-Abstract
Performance of green roof against the global warming
(2016-10-13) Dareeju, BSSS; Meegahage, JN; Halwatura, RU
In the past few decades, scientists are seeking to overcome issues; occurring due to global warming, which has reached into an alarming level. Global warming has led to many environmental issues including rising sea level and increasing indoor thermal discomfort. These sudden changes badly affect the occupants; living in the tropical climate condition which leads to enhance the heat discomfort in the buildings. As a result, researchers are forced to move towards the concept of sustainable building development for achieving better indoor thermal comfort. As a reason, the green roofs are accepted as a better alternative for overcoming impacts of global warming. However, the performance of the green roofs in a tropical climate is not addressed in Sri Lanka under the effects of global warming. This study emphasized on experimental approach of the green roof and its performance was measured by using small scale models. Using these results, large scale buildings were developed to simulate the performance of green roof under the effects of global warming. It was discovered that green roof provides an acceptable indoor thermal performance for global warming analysis than traditional roof types in Sri Lanka and green roof can be proposed as an ideal solution for achieving better indoor thermal comfort against the global warming effects.
item: Thesis-Abstract
Review of penetration grading system and suitability of the viscosity grading system for asphalt binders in Sri Lankan highways
(2015-06-26) Meegahage, JN; Mampearachchi, WK
Road development has become a dominant component in modern Sri Lanka. As a developing nation durability and long term performance of roads are very much important to the country. In Sri Lanka flexible pavements are the frequently used for road construction. In flexible pavement bitumen and aggregate are the main ingredients for surface layer. The quality of bitumen for roads is assessed using penetration grading system which was initiated in early 19th century. The quality of bitumen and the method of grading bitumen in Sri Lanka have made several discussions among the professionals because of the premature failures on some major roads. In this research twenty three bitumen samples were collected from various construction sites and tests were carried out to assess their quality. A sample of test reports issued by the bitumen suppliers were also taken in to consideration. Penetration test, Softening point test and Viscosity test were carried out using the collected samples. Penetration and Softening Point were assessed using the local bitumen specifications and viscosity was assessed based on the requirements of viscosity grading system. The Quality of bitumen was further analysed using the temperature susceptible measures such as Penetration Index, Viscosity Temperature Susceptibility and Pen-Vis Number. Relationship of temperature susceptibility measures were carried out using statistical means. Behaviour of bitumen at operation level was analysed using equi-viscous method of Asphalt Institute MS-2. Indirect methods were used to obtain the stiffness of bitumen and asphalt concrete. Stiffness measures were analysed with climatic considerations and traffic loading. Based on the test results and analysis, modifications for the standard of bitumen selection are recommended. Testing of bitumen properties at construction temperature range is essential. So, addition of kinematic viscosity at 135 C to the current specification in selecting bitumen for road construction in Sri Lanka and the importance of viscosity based grading system in bitumen selection was emphasized in this study.
item: Conference-Abstract
A review of penetration grading system and the suitability of alternate grading system for asphalt binders in Sri Lankan highways
(Department of Civil Engineering, University of Moratuwa., 2011-07) Meegahage, JN; Mampearachchi, WK; Pasindu, HR
Grading of asphalt cement is a very important factor in usage hot mix asphalt. It allows selecting the correct bitumen for road construction work. Bitumen or asphalt grading systems have changed from simple fundamental tests to more scientific methods in the past century. The development of grading of asphalt cement has lead to improve the performance of the road against the increasing traffic in last few decades. The fundamental test as chewing or penetration has been replaced by viscosity and aging properties of asphalt cement which gives more data about performance of roads. However, number of countries in the world including Sri Lanka still using the traditional penetration grading system while developed countries have advanced to viscosity and superpave grading system. In Sri Lanka, 80/100 asphalt cement was used for road construction up to the year 2003. Due to high surface undulation problems, 60/70 binder asphalt cement was introduced. However, surface undulation problems still remain. Sri Lanka is a country with different temperature zones and penetration grade system is more susceptible for temperature. This research attempts to review the use of penetration grading asphalt cement that is using Sri Lankan road construction and propose a possible alternative grading system. The important properties (viscosity, aging) of asphalt cement have not been tested in penetration grading system. There is no evidence for the performance of the properties of asphalt cement in mixing and laying temperatures. The research will penetrate through these facts and seek for better performance asphalt cement for Sri Lankan road construction.
item: Conference-Abstract
A review of penetration grading system and the suitability of alternate grading system for asphalt binders in Sri Lankan highways
(Department of Civil Engineering, University of Moratuwa, 2011) Meegahage, JN; Mampearachchi, WK; Pasindu, HR
Grading of asphalt cement is a very important factor in usage hot mix asphalt. It allows selecting the correct bitumen for road construction work. Bitumen or asphalt grading systems have changed from simple fundamental tests to more scientific methods in the past century. The development of grading of asphalt cement has lead to improve the performance of the road against the increasing traffic in last few decades. The fundamental test as chewing or penetration has been replaced by viscosity and aging properties of asphalt cement which gives more data about performance of roads. However, number of countries in the world including Sri Lanka still using the traditional penetration grading system while developed countries have advanced to viscosity and superpave grading system. In Sri Lanka, 80/100 asphalt cement was used for road construction up to the year 2003. Due to high surface undulation problems, 60/70 binder asphalt cement was introduced. However, surface undulation problems still remain. Sri Lanka is a country with different temperature zones and penetration grade system is more susceptible for temperature. This research attempts to review the use of penetration grading asphalt cement that is using Sri Lankan road construction and propose a possible alternative grading system. The important properties (viscosity, aging) of asphalt cement have not been tested in penetration grading system. There is no evidence for the performance of the properties of asphalt cement in mixing and laying temperatures. The research will penetrate through these facts and seek for better performance asphalt cement for Sri Lankan road construction.