Browsing by Author "Sitinamaluwa, HS"

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item: Conference-Abstract
Activated graphene oxide for removal of methylene blue from wastewater
(Department of Materials Science and Engineering, University of Moratuwa., 2023-07-28) Raveena, LAL; Viraji, HA; Rathnayake, RMSL; Sitinamaluwa, HS; Sivahar, V
Lately, activated oxidized graphene has sparked a lot of attention in the fields of wastewater treatment and water filtration. Here, the possibility for using activated graphene oxide (AGO) to remove methylene blue (MB) from water systems was investigated. Commercially available Graphene Oxide (GO) was obtained, and it was further modified by alkali-activation method to obtain AGO. The resulting AGO was tested as an adsorbent for methylene blue removal. Activation time was varied to optimize the MB removal of the adsorbent and then the adsorbents were characterized by using FTIR, SEM, BET and XRD analysis. Synthesized AGO shows prominent MB adsorption characteristics due to H-bonding, and electrostatic interactions. To evaluate the adsorption capacity, batch adsorption experiments were carried out and the effect of pH and temperature on dye adsorption were investigated. Maximum adsorption capacity of 123.47 mg/g was obtained for AGO sample which was activated for 1.0h and the data were well fitted to Langmuir isotherm model. These findings demonstrate the possibility for cationic dye removal from wastewater systems using an economically viable AGO.
item: SRC-Report
Deformation mechanisms of silicon electrodes in rechargeable Li-ion batteries
(2019) Sitinamaluwa, HS
Silicon has received a significant attention as a promising anode material for rechargeable Li-ion batteries owing to its high theoretical capacity (4200 mAhg-1) and relatively low operating voltage (0.4V vs Li/Li+). However, cycling performance of Si electrodes remains very limited due to large volume changes upon alloying and de-alloying with lithium, resulting in poor mechanical stability and early capacity fade. To address this issue, sound understanding of mechanical behavior of silicon electrodes during electrochemical lithium insertion is required. In this study, molecular dynamic simulation is employed to simulate the deformation behavior of lithiated amorphous silicon (a-Si) under nanoindentation at different stages of lithiation. The results are used to characterize the effect of Li concentration on hardness and modulus of the electrode, as well as the lithiation-induced plastic deformation. The effect of Li concentration on mechanical properties and deformation mechanisms are thoroughly explored during the nanoindentation process. The results indicate the transition of the properties of a-Si electrode with lithiation; from a hard, covalent solid into a soft, ductile alloy which can accommodate large plastic deformation. Obvious elastic and plastic deformations occur under the nanoindentation of a-Si and LixSi. Clearly different deformation mechanisms of Li-poor structures and Li-rich structures under indentation are revealed. Plastic deformation of a-Si is governed by the increasing fivefold coordinates of silicon network structure. In contrast, plastic flow of Li-rich structures is found to be governed by migration of shear transformation zones. Increased disorder of Li-Si alloys with electrochemical Li insertion might play a vital role on the formation of shear transformation zones in Li-rich LixSi alloys
item: Conference-Abstract
Determination of moisture content of wood using ultrasonic pulse velocity
(Department of Materials Science and Engineering, 2019-01) Vithanage, VSC; Wijesinghe, MPMC; Piyathilake, SAKVM; Sivahar, V; Sivahar, V; Sitinamaluwa, HS
Wood is one of the conventional materials still used in many engineering applications. As a natural material, it is subjected to dynamic property variations. One of the major reasons for the property variation of wood is the moisture absorption. The main aim of this research is to estimate the degree of decay in the compressive strength of selected wood types against the amount of moisture using ultrasound waves. Teak (Tectonagrandis), a hardwood and Pine (Pinusthaeda), a softwood are two types of wood which are commonly used in Sri Lankan wood industry. Samples of each wood type were kept for moisture absorption and the ultrasonic pulse velocities were measured in each sample. A 54 kHz normal probe was used. Through transmission technique was carried out in longitudinal and transverse directions. The corresponding compressive strength was also tested for each moisture level in the defined directions. In the transverse direction, ultrasonic velocity and compressive strength showed relatively lower values than those in the longitudinal direction. The ultrasound velocity was found to drop with the increase in moisture content. The rate at which the velocity drops changed at a particular moisture content. It was noted that this moisture content is the Fiber saturation point (FSP) of the wood tested. This phenomenon is common for both the wood types in both the directions. The fiber saturation point of each sample was confirmed with DSC (Differential Scanning Calorimetric) analysis. The established relationships can be used to estimate the compressive strength of wood nondestructively for a known moisture content.
item: Thesis-Abstract
Development Of A Guideline For Implementation Of Polymer Modified Biutmen For Hma Based On Empirical Test Methods
(2014-08-12) Sitinamaluwa, HS; Mampearachchi, WK
Polymer modification of bitumen has increasingly become the norm in designing optimally performing pavements. Pavements with polymer modification exhibits greater resistance to permanent deformation and thermal cracking, and decreased fatigue damage and temperature susceptibility. Polymer Modified bitumen (PMB) are effectively used in many countries over last three decades to construct pavements with superior performance and extended service life. This research was aimed at identifying the need to implement PMB in Sri Lanka, and also developing a testing procedure for PMB based on currently available empirical test methods. Five unmodified binders used in Sri Lanka was subjected to a series of laboratory testing in order to study their temperature susceptibility, high and low temperature behavior and moisture damage. The results were compared with the existing pavement conditions and it was understood that their performance is limited in above mentioned aspects. To understand the performance of PMB, a case study was done using two PE modified bitumen samples and two SBS modified bitumen samples. They were subjected to a series of laboratory tests which confirmed that the both types of PMB are suitable to overcome the limitations exhibited by unmodified binders. The necessity of having a proper testing procedure for PMB is discussed and a specification was proposed considering the available testing facilities in Sri Lankan Laboratories. The test methods were selected considering the adequate control of binder properties during application and usage. Penetration test is included to control the intermediate temperature properties and for the identification of binder grades. Softening point test controls the high temperature properties while viscosity test controls the mixing and compaction temperatures. Elastic recovery test and solubility test were employed in order to identify the amount of polymer in PMB. Storage stability test determines the separation tendency of polymer from bitumen. Flash point limits are set for the application safety. Thus all the essential parameters of bitumen are controlled by the proposed specification. The requirement limits are set considering different PMB specifications of several other countries, past research outcomes and laboratory test results. The proposed specification which is based on empirical test methods facilitates an adequate quality control of Polymer Modified Bitumen and it would be a useful guideline for implementation of PMB for HMA in Sri Lanka
item: Conference-Abstract
Development of a lab scale dynamic mechanical analyzer
(Department of Materials Science and Engineering, 2019-01) Rathnayaka, RMPC; Madushani, HDT; Weragoda, VSC; Sivahar, V; Sitinamaluwa, HS
Dynamic mechanical properties refer to the response of a material when it is subjected to a periodic strain. Dynamic mechanical analysis (DMA) is an important technique used to measure the mechanical and viscoelastic properties of materials such as thermoplastics, thermosets and elastomers. The aim of this research is to study the Dynamic Mechanical behavior of elastomer compounds by developing a lab-scale dynamic mechanical analyzer. The apparatus was designed to record a test specimen's reaction force when a systematically varying gradual strain development is applied. The phase difference between the applied strain and the material's response in terms of force was used to estimate the storage modulus and loss modulus to analyze the material properties. Furthermore, the dynamic modulus, dynamic loss modulus, and the mechanical damping coefficient of the elastomer could be estimated using the developed dynamic mechanical analyzer. The values obtained using the developed apparatus showed a fairly good agreement with the values for the same compound obtained from Prescott instruments ODR. The deviations were within 3.5%. One of the major shortcomings of the apparatus was the fact that the operating frequency was limited to IHz and there is no provision for carrying out measurements in varying temperature conditions.
item: Conference-Abstract
Development of a photosensor based on photo dielectric effect of cadmium sulphide
(Department of Materials Science and Engineering, 2019-01) Kumari, TID; Jayasumana, MASD; Attygalle, D; Sivahar, V; Sitinamaluwa, HS
A photosensor is an electronic component that detects the presence of visible light, infrared transmission (IR), and/or ultraviolet (UV) energy. A photosensor which changes its electrical capacitance in the presence of visible light was developed based on the photo-dielectric effect of Cadmium Sulphide (CdS). This photosensor was fabricated by depositing a CdS thin film on Fluorine-doped Tin Oxide glass (FTO glass). FTO acts as the front electrical contact and an aluminum sheet acts as the back contact, where a 2.0)im - 3.0)im thick CdS thin film acts as the photo-dielectric material. Chemical bath deposition method was used for CdS fabrication and the CdS thin film with optimum photovoltaic and micro structural properties was obtained at a bath temperature interval of 40 - 45 °C, annealing temperature of 180-220 °C. Film thickness was varied by adjusting deposition time and the number of coatings. Thickness variations were determined using a Scanning Electron Microscope (SEM). The transmittance and absorbance spectra are recorded in the range of 200 nm - 1100 nm. CdS thin film fabricated under optimum conditions resulted in a bandgap in the range of 2.30 eV-2.40 eV, which is closely agreeing to the theoretical value of 2.42eV. The photo-capacitance and photoconductivity were measured in a frequency range of 1 kHz to 5 MHz in dark and illuminated conditions. The Cole-Cole plots were analyzed to identify the most sensitive operational frequency for the device.
item: Article-Full-text
Development of a polymer-modified bitumen specification based on empirical tests – case study for Sri Lanka
(2016-05-24) Sitinamaluwa, HS; Mampearachchi, WK
Pavements with polymer modification exhibit greater resistance to permanent deformation, less thermal cracking, less fatigue damage and less temperature susceptibility. Implementation of polymer-modified bitumen (PMB) is currently taking place in developing countries and the absence of PMB specification has always been a constraint. This research was aimed at developing a testing procedure for PMB, based on test methods that are currently available in Sri Lankan laboratories. The test methods were selected considering the adequate control of binder properties during application and usage. Penetration test is included to control the intermediate temperature properties and identify binder grades. Softening point test controls the high-temperature properties while viscosity test controls the mixing and compaction temperatures. Elastic recovery test and solubility test were employed in order to identify the presence of polymer in PMB. Storage stability test determines the separation tendency of polymer from bitumen. Flash point limits are set for the application safety. Thus all the essential parameters of bitumen are controlled by the proposed specification. The acceptance limits are determined considering different PMB specifications of several other countries, past research outcomes and laboratory test results. The proposed specification which is based on empirical test methods facilitates adequate quality control of PMB and it would be a useful guideline for the implementation of PMB for hot mix asphalt in Sri Lanka.
item: Conference-Abstract
Development of a vibration and shock sensor using piezoelectric ceramics
(Department of Materials Science and Engineering, 2019-01) De Silva, HTTM; Dayananda, RKAS; Adikary, SU; Sivahar, V; Sitinamaluwa, HS
When buildings are exposed to vibration or shock, those buildings can be damaged partially or fully depending on the energy of vibration. Hence, quantitative analysis of building vibration has become popular among researchers. In this research, a vibration sensor was developed using a piezoelectric ceramic cantilever beam and a tip mass to confirm that the vibration frequency of the building does not exceed the cosmetic damage range. As the first step, a mathematical model was developed to calculate the resonance frequency of the cantilever beam with a tip mass. At the resonance frequency, maximum amplitude could be achieved resulting in a higher output voltage of the piezoelectric sensor. The developed mathematical model and finite element analysis were used to determine the accurate dimensions of the cantilever beam based piezoelectric sensor. According to the calculations, width, length and thickness of the piezoelectric material, copper beam and tip mass are 10x20x1, 10x100x0.3 and 10x30x3 mm respectively. Hence, the piezoelectric sensor output voltage was calculated using finite element analysis at the vibration frequency range that corresponds to the cosmetic damage. According to the calculations, threshold voltage level and frequency of the sensor to activate the alarm were 4.35 mv and 9.5 Hz respectively. Arduino software was used to analyze the output signal of the sensor. Vibration source was used to verify the calculation steps. Finally, liquid crystal display and small buzzer were added to show the frequency and give a warning when vibration frequency exceeds the required level.
item: Conference-Abstract
Development of cement, sand and sawdust based composite material to use as plaster for walls
(Department of Materials Science and Engineering, 2019-01) Ekanayaka, EMCHB; Fernando, KKA; Udayakumara, SV; Sivahar, V; Sitinamaluwa, HS
With the arisen development around the world, the demand for natural construction materials has been increased. Increasing consumption levels decrease the amount of available natural resources. The importance of material efficiency and the need to improve it can be studied from several perspectives. Limited availability or scarcity of materials may lead to threats to the economy, and the production processes of materials can have significant environmental impacts. This study was concentrated on the use of sawdust as a partial replacement for fine aggregates in cement-based wall plaster material. Mahogany sawdust produced in local timber mills was selected for the study. Sawdust was incorporated into the plaster mixture in the raw form as well as in burnt form (saw dust ash). Composites were prepared by incorporating 5% and 10% saw dust by weight and sawdust ash by weight. Prepared composites were tested for flexural strength and tensile strength according to BS EN 1015 standard. Lee's disc method was used to compare the thermal properties of the composites. Composite with 5% saw dust ash showed better properties compared to the composites with other sawdust combinations.
item: Conference-Abstract
Development of Graphene Oxide based capacitive gas sensor for NO2 detection
(Department of Materials Science and Engineering, 2019-01) Deemantha, MBA; Gunasena, RGSP; Amarasinghe, DAS; Sivahar, V; Sitinamaluwa, HS
Parallel plate capacitive gas sensor was assembled using Graphene Oxide (GO) as the transducer material. The sensor was tested with NO2 as the target gas. GO was synthesized according to the Improved Hummer's Method (Tours Method) in which vein graphite was sufficiently oxidized. Synthesized graphene oxide was characterized by Fourier Transform Inirared Spectroscopy (FTIR) and Thermogravimetric Analysis (TGA) ascertaining that products were well oxidized. Sensor was tested for capacitance variation in the fi^equency and time domains under the influence of constant temperature ramp. The results showed an average response time of about 2 minutes to reach the steady state signal and an equal time to reach the initial reference signal levels once the testing chamber was evacuated of the target gas.
item: Conference-Abstract
Development of nano silver impregnated food packaging materials
(Department of Materials Science and Engineering, 2019-01) Samarasekara, AMPB; Amarasinghe, DAS; Madhushan, WKP; Chathuranga, SN; Sivahar, V; Sitinamaluwa, HS
The growing demand for increased shelf-hfe of food and the need for protection against foodbome diseases, fiiel the development of new food packaging materials. Silver-nanoparticle (AgNp) impregnated packaging materials are promising candidates for active food packaging. These active packaging materials are capable of extending the shelf-life of foods and reducing the risk of pathogens. The current research work is focused on the development of AgNp incorporated coating for polymer-based food packaging. AgNp dispersed in polyvinyl alcohol solution was prepared by in situ reduction method, in which silver nitrate and polyvinyl alcohol (PVA) acted as precursor and capping agent respectively. Presence of silver nanoparticles in the solution was confirmed by photoluminescence spectroscopy and UV-Vis spectroscopy. In order to reduce coating solubility PVA solution was cross-linked. The compatibility of the coating with the substrate was enhanced by plasma treatments. Contact angle measurements were employed to monitor the wettability changes. The solubility of the coating was examined by gravimetric methods. The effects of cross-linked temperature and cross-linked agents on solubility were studied. The presence of silver nanoparticles in the coating was confirmed by surface plasmon resonance and electron micrographs. The modified Kirby-Bauer (disk diffusion) method was employed to measure the anti-bacterial effect of the coating.
item: Conference-Abstract
Development of polylactic acid (PLA) based biodegradable packaging materials
(Department of Materials Science and Engineering, 2019-01) Dhanushka, MKDT; Kaushalya, RANC; Samarasekara, AMPB; Sivahar, V; Sitinamaluwa, HS
The key purpose of packaging is to protect the contents or products from external factors. Synthetic polymers do not degrade completely in nature after the usage and create environmental issues. Therefore, there is a tendency to substitute such polymers with natural polymers that are easily biodegraded and less likely to cause environmental pollution. The main objective of this research is to develop a biodegradable packaging material based on Polylactic Acid (PLA) and locally extracted starch. Starch was extracted from cassava tubers by crushing, blending and sedimentation processes. The extracted product was characterized by Fourier Transform Infrared Spectroscopic technique (FTIR). Experimental results indicated that 25 wt.% of starch could be extracted from the cassava that was tested. Biodegradable PLA and starch-based blends were prepared by adding starch as the main additive. The dried starch was incorporated into the PLA and melt-blended using laboratory scale internal mixer. A mixing process was performed for various starch concentrations. The blended samples were then pressed to form thin sheets in a hydraulic press. Soil burial test was performed to analyze the biodegradability of the developed product. The tensile strength and elongation at break of the samples were determined by tensile testing. Weight loss in starch-containing samples gradually increased with time during the soil burial test. Experimental results also indicated that biodegradability of the products increased as the starch content is increased. The mechanical properties such as tensile strength and elongation also decreased as the starch content increased. These results indicated that the addition of starch to PLA is a better method to increase the biodegradability of the PLA -starch blends. These developed biodegradable materials can be used as a sustainable material to create safer environment.
item: Conference-Abstract
Development of polymer modified bitumen specification for Sri Lanka
(Department of Civil Engineering, University of Moratuwa., 2012-07) Sitinamaluwa, HS; Mampearachchi, WK; Pasindu, HR
Implementation of polymer modified bitumen (PMB) is a new movement of Sri Lankan highway industry and it has become a challenging task for many reasons. One is, currently used penetration grading system is inadequate for proper quality control of PMB. The improper use of PMB would result in poor pavement performance and will lead to serious maintenance and cost issues. And the lack of experience of Sri Lankan engineers is a problem since a very strict process control is required. Hence there is the need of a proper guideline to implement PMB in Sri Lanka. The Performance Grading system is considered as the most effective specification for bitumen since the test methods capture fundamental rheological properties of bitumen. This was successfully implemented in USA; but is lagging in other parts of the world due to the cost and complexity of the new test equipment. But the empirical tests also are taken as indirectly related to the road performance for centuries. In PMB specifications of countries such as Australia, UK, India, Brazil, China etc. it is evident that the used test methods does not necessarily measure fundamental rheological properties of bitumen, but the empirical tests which are indirectly related to the characteristics of bitumen. In this research, the possibility of developing a Sri Lankan Specification of PMB with available test methods was studied. The important bitumen properties that are necessarily needed to be controlled are identified and the test methods which can determine those characteristics are included in the specification. Requirement limits for each test are set according to literature findings. Here the controlling of mixing and compaction temperatures for PMB was specially considered since it is a major practical issue. Further development for this specification can carry out with the experience of SL engineers in future, and the developed specification would be a great assistance for earlier stages of PMB pavements in Sri Lanka.
item: Conference-Abstract
Development of thermal insulator based on phase change materials
(Department of Materials Science and Engineering, 2019-01) Jayawardhana, SHP; Umayanga, PKA; Attygalle, D; Sivahar, V; Sitinamaluwa, HS
Thermal Energy Insulation is very important, especially for energy saving purposes. The use of Phase change material (PCM) for Thermal Energy Insulation (TEI) is technique That is being studied extensively for building temperature regulation Phase change material (PCM) generally used for this purpose have low melting temperature and high latent heat of melting-solidification. Latent heat thermal energy insulates (LHTEI) with phase change materials (PCMs) deserves attention as it provides high energy density and small temperature change interval upon melting/solidifying and provide thermal regulation at particular phase change temperatures. This study aimed to modify thermal insulator based on commercially available paraffin with melting point (Tm) around 60 ? . A series of experimental data were collected irom a representative prototype construction, observing the temperature variation of enclosed system to identify the cutoff temperature. Using paraffin oil and coconut oil modified paraffin under different mass fi^actions of paraffin were studied to find the optimum combination. DSC/TGA and Lee's disc methods used to characterize the modified PCM to select better material for study.
item: Conference-Abstract
Effect of carbon content on the correlation between ultrasonic attenuation and corrosion of plain carbon steel
(Department of Materials Science and Engineering, 2019-01) Metthananda, SHGK; Tennakoon, GAAI; Sivahar, V; Piyathilake, SAKVM; Sivahar, V; Sitinamaluwa, HS
The field of Metallurgical Engineering includes a vast range of applications from tiny mechanical components to massive construction applications. The service life of metals is highly concerned and studied extensively. Among all industrial metals, plain carbon steel plays a considerable role. Detecting the actual amount of corrosion has become very vital and critical since the failures occurring due to corrosion is still a substantial problem. Ultrasonic Testing is one of the modem methods which can be used to identify the degree of corrosion of a metallic component accurately, without causing any destruction. This study sought to contribute the field of metallurgical engineering by identifying the effect of carbon content and ultrasonic attenuation towards the corrosion of plain carbon steels. Plain carbon steel samples of different carbon contents were allowed to corrode under accelerated environment and periodically tested for ultrasonic attenuation and weight loss measurements. In addition, corrosion penetration of the samples was examined under optical and scanning electron microscopes. Observations were taken for both destructive and nondestructive testing and were correlated so that, using this correlation, the degree of corrosion can be determined in a non-destructive way without damaging the components and hence the remaining service lifetime could be predicted.
item: Conference-Abstract
Effect of penetration of corrosion on the load-bearing capacity of mild steel
(Department of Materials Science and Engineering, 2019-01) Jayasooriya, ED; Munasinghe, RGNDS; Sivahar, V; Sitinamaluwa, HS
The field of Metallurgical Engineering associated with the estimation of the service life of corroded structural members which has been studied in extensive detail, the world over. Most of the research work in this area have focused on the general attack (uniform corrosion) faced by steels across a range of atmospheres. This study sought to contribute to this field by examining whether the penetration of corrosion beyond the general attack has a significant effect on the load-bearing capacity of mild steel. Mild steel samples were corroded in an aggressive atmosphere over a 5-month period, subjected to periodic tensile testing and corrosion mass-loss analyses and examined under optical and electron microscopy. Through the identification and measurement of the penetration of corrosion using scanning electron microscopy, this research managed to correlate corrosion mass-loss and tensile load-loss data with said microscopic measurements. The results showed that the actual fracture loads deviated negatively from the expected load- bearing capacity, which was determined through conventional methods. This deviation showed a close correlation to the increase of penetration of corrosion with time. As a result of this correlation, the research concluded that allowances ought to be made for the penetration of corrosion when the remaining service life of corroded load-bearing members has to be calculated more accurately.
item: Conference-Abstract
Electrode – electrolyte interface analysis by molecular dynamics simulation
(Department of Materials Science and Engineering, University of Moratuwa., 2021-12) Virajini, RLAC; Sitinamaluwa, HS; Abeygunawardana, AAGA
The research for renewable energy generation methods requires the development of novel, sustainable energy storage methods. Supercapacitors are much promising for future energy storage applications, owing to their high energy density and rapid charge-discharge time. supercapacitors are widely used in the following ways: firstly, the largest proportion of commercial supercapacitors are used in consumer electronics, in which they mainly serve as backup sources for memories, system boards, clocks and microcomputers; secondly, supercapacitors are used as the main power source, such as fail-safe positioning devices and starter applications. The performance of supercapacitors can be improved by using high surface area electrode materials, which could increase the energy density of the device. In this regard, nanomaterials are much advantageous owing to their high surface to volume ratio. In this study, graphene and titanium dioxide nanotube arrays are studied as a supercapacitor electrode material, using molecular dynamic simulation. This study focuses on mathematical modeling of electrode-electrolyte interface, to study the charge storage mechanism of the electrode when in contact with the electrolyte. Firstly, the molecular dynamic simulation (MD simulation) method was used to study graphene-electrolyte system using a planar electrode model. There, the formation of electric double layer with different charge levels are studied. secondly, molecular dynamics simulations have been conducted to study the interaction between anatase TiO2 (100) surface and water. The effect of surface orientation of the TiO2 surface on the interface properties was studied.
item: Conference-Abstract
Evaluation of feasibility of polymer modified asphalt binders for Sri Lankan conditions
(Department of Civil Engineering, University of Moratuwa., 2011-07) Sitinamaluwa, HS; Mampearachchi, WK; Pasindu, HR
Polymer modification of asphalt binders has increasingly become the norm in designing optimally performing pavements. Pavements with polymer modification exhibits greater resistance to permanent deformation and thermal cracking, and decreased fatigue damage and temperature susceptibility. Polymer Modified binders (PMB) are effectively used in many countries, such as USA, Europe, Australia and India over last three decades to construct pavements with the superior performance and Extended service life. In Sri Lanka 80/100 and 60/70 penetration grade bitumen has been used and it is observed that both binders cannot perform satisfactorily due to their temperature susceptibility. Modification of bitumen decreases the temperature susceptibility and therefore now it's time to Sri Lanka to move forward from conventional binders to modified binders. Initial step of this research was to study about functionality of polymer modified bitumen and evaluating the need of polymer modified binders for Sri Lanka. After reviewing available data, it was identified that most suitable polymer modifiers for Sri Lanka are SBS, EVA, SBR, PE and Crumb rubber. Modification up to 4% - 8% of polymer is recommended and the modification level can vary with the desired properties of binder. That depends on the factors such as temperature, moisture level and other climatic conditions of the area and also traffic level. PMB has to be characterized differently from penetration grade bitumen and the improved performance properties are difficult to demonstrate with conventional empirical rheological tests. This research is focused on reviewing the available PMB specifications and finally come up with a set of required properties for modified binders relevant to Sri Lankan roads, required testing methods and handling procedures for PMB. The final outcome of this research would become a good initiating point for local highway engineers to move from conventional binders to modified binders.
item: Conference-Abstract
Evaluation of feasibility of polymer modified asphalt binders for Sri Lankan conditions
(Department of Civil Engineering, University of Moratuwa, 2011-07) Sitinamaluwa, HS; Mampearachchi, WK; Pasindu, HR
Polymer modification of asphalt binders has increasingly become the norm in designing optimally performing pavements. Pavements with polymer modification exhibits greater resistance to permanent deformation and thermal cracking, and decreased fatigue damage and temperature susceptibility. Polymer Modified binders (PMB) are effectively used in many countries, such as USA, Europe, Australia and India over last three decades to construct pavements with the superior performance and Extended service life. In Sri Lanka 80/100 and 60/70 penetration grade bitumen has been used and it is observed that both binders cannot perform satisfactorily due to their temperature susceptibility. Modification of bitumen decreases the temperature susceptibility and therefore now it's time to Sri Lanka to move forward from conventional binders to modified binders. Initial step of this research was to study about functionality of polymer modified bitumen and evaluating the need of polymer modified binders for Sri Lanka. After reviewing available data, it was identified that most suitable polymer modifiers for Sri Lanka are SBS, EVA, SBR, PE and Crumb rubber. Modification up to 4% - 8% of polymer is recommended and the modification level can vary with the desired properties of binder. That depends on the factors such as temperature, moisture level and other climatic conditions of the area and also traffic level. PMB has to be characterized differently from penetration grade bitumen and the improved performance properties are difficult to demonstrate with conventional empirical rheological tests. This research is focused on reviewing the available PMB specifications and finally come up with a set of required properties for modified binders relevant to Sri Lankan roads, required testing methods and handling procedures for PMB. The final outcome of this research would become a good initiating point for local highway engineers to move from conventional binders to modified binders.
item: Conference-Extended-Abstract
Extraction and usage of pectin to enhance biodegradability of LDPE blends
(2010) Sitinamaluwa, HS; Somasiri, GWD; Samarasekara, AMPB
Blends of pectin and low density polyethylene (LDPE) were prepared and the effect of pectin on biodegradability was analyzed Pectin was extracted front passion fruit peels hy hot acid extraction with a yield of 20 wt.%. I he physical, mechanical and chemical properties of the blends were investigated using Fourier Transform Infrared spectroscopy (f IIR). tensile test, water absorption test and optical and electron microscopy. The biodegradability wits evaluated by time dependent weight loss using soil burial test. The test results showed that weight loss up to 4.5% in 14 weeks period. Pectin addition had a positive impact on enhancement of biodegradability of LDPE blends.