Browsing by Author "Christopher, W.A.P.P."
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Item Characterisation of “Dummala” Origin in Sri Lanka by XRF, XRD and FTIR(Uva Wellassa University of Sri Lanka, 2019) Subasinghe, H.C.S.; Bandara, T.G.T.A.; Christopher, W.A.P.P.; Hewathilake, H.P.T.S.; Pitawala, H.M.J.C.The term Dummala is a traditional name given to the naturally occurring substance that can be found, either at uppermost crustal levels, mostly under the freshwater swampy areas or as a dried resin like gums from the Dummala tree (Shorea oblongifolia), which is endemic to Sri Lanka. The history of Dummala is dated back to more than 2000 years, where it was used in ayurvedic medication and to make flares in exorcisms and processions. Dummala which is taken out from ground, physically appears as peat-like carbonaceous matter with agglomerated coarse-grained particles. Though, this variety of Dummala is naturally occurring material found in Sri Lanka a firm scientific analysis has not yet been conducted. Therefore, this study aims to characterise the Dummala extracted from the ground, in order to investigate the chemical composition and special properties that might be suitable for the advanced applications. Initially, natural Dummala was dried and 50 g of sample (<53 µm) was obtained by mechanical sieving. X-Ray Fluorescence (XRF) spectroscopic analysis were conducted to identify the chemical composition. Further, Dummala was characterised with X-Ray Diffraction (XRD) analysis for the phase identification and the results showed that this material is partially crystalline. XRF data together with XRD analysis confirmed that Dummala which is taken out from the ground is composed mainly with Magnesium Carbonate, Silica and Sulphur. Further, the present study suggests a carbon content analysis in order to interpret the origin of Dummala.Item Substitution of Rice Husk Ash for Grout Additive to Decrease Shrinkage of Cement Grouting(Uva Wellassa University of Sri Lanka, 2019) Anojan, K.; Amaraweera, T.H.N.G.; Christopher, W.A.P.P.; Sarathkumara, W.Rice husks are the protecting covering of grains of rice. They are formed from hard materials, including opaline silica and lignin, to protect the seed during the growing season. Rice milling industry generates substantial amounts of rice husk during milling of paddy, which is mostly used as a fuel in rice milling industry. Rice Husk Ash (RHA) is about 25% by weight of rice husk when burnt in boilers. Chemicals used in grouting may be replaceable with waste material from the rice milling industry when it is processed to RHA to decrease the shrinkage while increasing the strength. This study aims to substitute RHA as a grout additive in cement grouting and identify an optimum amount of RHA. First rice husk was burnt in a muffle furnace under controlled temperature which started at room temperature and was gradually increased up to 680 ℃ for about 6 hrs before it was allowed to cool down to room temperature (25 ℃). RHA sample was sieved by using 150 µm sieve. The cement: grout additive: water mixing ratio 2000:9:840 respectively. Then RHA was added replacing varying amounts of grout additive. The grout mixture was prepared manually by hand since the samples were too small to mix using a mixing machine. The proto type samples made were passed the strength tests according to the British Standard 1881. Mixing with a mixer would decrease the variation of results. According to the compressive strength, samples which contain high rice husk ash content were having a high compressive strength. Furthermore, the strength increased after 28 days was 49 MPa. Thus, the conclusion can be drawn that substitution of RHA for grout additive is possible and positive with gained strength.Item Synthesizing Electro - conductive grease using graphite(Uva Wellassa University of Sri Lanka, 2015) Christopher, W.A.P.P.; Cooray, J.T.; Attanayake, A.N.B.Graphite as we all know is well renowned for its ability to conduct electricity as well as its lubricant nature. The carbon atoms in graphite are sp2 hybridized. Each carbon atom bonds with three other carbon atoms via the three sp2 hybridized atoms to form a sheet of carbon atoms lying in a hexagonal pattern or a honey comb structure and carbon atoms are bound together by strong covalent bonds. And each of these sheets of carbon is bound together by weak van der Waals bonds. The fourth electron in a p orbital is left free and its these electrons that contribute towards the electrical conductivity of graphite. Grease is a semi solid lubricant widely used in the industrial world to reduce ware and tare. Grease is made of three principal components known as a base oil, thickener and additives. Thus combining graphite with grease would preferably transfer the electro-conductive nature of graphite to grease forming an electro-conductive grease. Usage of such a product would be, grounding static discharges, providing electrical continuity between irregular or pitted surfaces, ensuring electrical contact between loose or vibrating parts and small gaps, application to ball bearings in computer equipment where it allows static discharge to pass through the bearing instead of building up and arcing. Synthesizing such a graphite based grease product was the main objective of this study. Materials and methodology Natural vein graphite was used to make graphite powder under 75 microns. Basic grade grease was used as the substrate. Different weight ratios of both graphite and grease were mixed by blending to generate the sample series. The samples were tested for electrical conductivity using the impedance analyzer. A standard cell was made to hold the sample. The conducting length was kept to a minimum assuming that in real world applications (12 millimeters). The cell electrodes were designed in such a manner that two over rings were placed to ensure that the effective conducting length was kept constant throughout the sample series tested. Three measurements were taken with each generating a graph of imaginary part of impedance versus the real part of it. And the resistance of the sample was determined by the point where the curve seemed to make contact with the x axis of the graph. And the capacity of the particular sample can be determined by finding out the frequency of the peak point of the semicircle.Item Synthesizing Electro- Conductive Grease Using Graphite(Uva Wellassa University of Sri Lanka, 2014) Christopher, W.A.P.P.Graphite as we all know is well renowned for its ability to conduct electricity as well as its lubricant nature. Graphite has a honey comb structured planes where carbon atoms are bound together by strong covalent bonds. And each of these layers of carbon is bound together by weak van der Waals bonds. Grease is a semi solid lubricant widely used in the industrial world to reduce ware and tare. Grease is made of three principal components known as a base oil, thickener and additives. Thus combining graphite with grease would preferably transfer the electro-conductive nature of graphite to grease forming an electro-conductive grease. Usage of such a product would be, Grounding static discharges, provides electrical , • continuity between irregular or pitted surfaces, ensures electrical contact between loose or vibrating parts and small gaps, apply to ball bearings in computer equipment where it allows static discharge to pass through the bearing instead of building up, arcing, extending the Life of Rotating Switches, preventing Corrosion on Knife Switches, grounding Ball and Socket Connections on Power Insulators. Natural vein graphite was used to make graphite powder under 75 microns. Basic grade grease was used as the substrate. Different weight ratios of both graphite and grease were mixed by blending to generate the sample series. The samples were tested for electrical conductivity using the impedance analyzer. A standard cell was made to hold the sample. The conducting length was kept to a minimum assuming that in real world applications (12 millimeters). Three measurements were taken with each generating a graph of imaginary part of impedance versus the real part of it. And the resistance of the sample was determined by the point where the curve seemed to make contact with the x axis of the graph. The samples show a near linear variation of both characteristics of conductivity and capacity. But the fmal sample containing 35% graphite with 65% grease shows a significant elevation in both conductivity and capacity. With a conductivity value of 4.2008 x 10 S cnil this particular sample is in the region of semiconductors with respect to conductivity