Browsing by Author "Subasinghe, H.C.S."

Now showing 1 - 4 of 4
  • Thumbnail Image
    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.
  • No Thumbnail Available
    Item
    Geochemical Variations of Prospective Heavy Mineral Deposits Bordering the Coastline of Sri Lanka
    (Uva Wellassa University of Sri Lanka, 2021) Subasinghe, H.C.S.; Ratnayake, A.S.; Wijewardhana, T.D.U.; Sameera, K.A.G.
    Heavy minerals with a specific gravity greater than 2.9 g/cm3 such as ilmenite (FeTiO3), rutile (TiO2), leucoxene (altered ilmenite), zircon (ZrSiO4), monazite ((Ce,La,Nd,Th)PO4), garnet ((Ca,Mg,Fe,Mn)3(Al,Fe,Mn,V,Cr)2(SiO4)3), sillimanite (Al2SiO5), and magnetite (Fe3O4) have gained global attention as a result of modern technological advances. In this regard, the mining and processing of these heavy minerals are a timely requirement to uplift the mineral industry and the economy of Sri Lanka. Therefore, the objective of this study is to investigate the geochemical variations of prospective heavy mineral deposits along the coastline in order to identify locations with economically significant concentrations of heavy minerals. Field excursions were carried out to identify the potential of heavy mineral placers in Sri Lanka. Sediment samples were collected from ten locations covering both the shoreline and raised beaches. X-ray fluorescence (XRF) analysis was used to determine the major and trace element compositions of sediments. When compared to average Upper Continental Crust (UCC) values, major and trace element variations show the enrichments of TiO2, Fe2O3, La, Ce, Zr, Cr, Nb, Th, and V. The abundance of TiO2, Fe2O3, and Zr, and visual examination of samples suggest the presence of higher concentrations of heavy minerals such as ilmenite, rutile, and zircon in the prospective locations. Moreover, the abundance of trace elements such as La, Ce, and Th implies the presence of rare earth elements (REEs) bearing heavy minerals such as monazite and zircon. In contrast, major elements (Al2O3, Na2O, and K2O) and large- ion lithophile elements (Ba and Rb) were significantly depleted compared to UCC values. Based on the XRF data and visual examination, it can be concluded that all the studied locations such as Verugal, Dickwella, Kosgoda, Payagala, Beruwala, Kalutara, Dharga Town, and Aruwakkalu can be identified as potential sites for heavy mineral placers. Finally, proper quantification is required to estimate economic grade and to determine mining feasibility. Keywords: Heavy minerals; Geochemical variation; Economic concentrations; Coastline of Sri Lanka
  • No Thumbnail Available
    Item
    Incorporation of Polymer Material to Enhance Properties of Traditional Asphalt: A Review
    (Uva Wellassa University of Sri Lanka, 2020) Subasinghe, H.C.S.
    Sustainability and green concepts are currently acknowledged throughout the global construction industry. The present study is focussed to review the effects of polymer incorporated traditional asphalt. Besides, wearing of roads due to the melting of nearsurface tar has become a critical issue in road construction. The traditional material used in road construction is a mixture of rock aggregates with bitumen. However, the introduction of waste plastics such as polythene bags, cups, bottles, and polyethylene terephthalate (PET) is highly appreciated. Since the plastics and polythene are nonbiodegradable, these have become the major environmental pollutants around the World. However, these have been effectively incorporated in the asphalt mixture to be used in the construction of roads. According to literature, various polymer materials have been preheated at 150°C-200°C until the melt is well liquefied. The well-heated aggregates have then been added to the polymer melt. Thereafter, the plastic-coated aggregates have been mixed with bitumen to produce the polymer mixed asphalt composite (Plastiphalt). The mechanical properties of the composite have shown excellent strength values. Further, this composite has shown higher wear resistance and the melting of bitumen during exposure to sunlight has also reduced. Thereby, the durability of plastiphalt has been concluded to be much higher than the traditional asphalt material. Moreover, the dark black colour has also been reduced, thus minimizing heat absorbance to the inner material. The surficial oil formation of newly paved roads has also reduced. Consequently, road safety has been increased with a reduced number of accidents during rainy seasons. Therefore, the utilization of abundantly available waste plastics in road construction is highly recommended to developing countries such as Sri Lanka. Keywords: Plastic waste, Eco-friendly, Roads, Asphalt, Durability
  • No Thumbnail Available
    Item
    Preliminary Investigations of Geochemical Characterization in Murunkan Clay Deposit, Sri Lanka
    (Uva Wellassa University of Sri Lanka, 2020) Subasinghe, H.C.S.; Gayashini, K.Y.; Ratnayake, A.S.; Wijewardhana, D.T.U.; Pitawala, H.M.J.C.; Attanayake, A.M.A.N.B.
    Clay minerals are categorised into several groups as kaolin group, smectite group, illite group, chlorite group and 2:1 clays such as attapulgite and sepiolite. Over other clays, smectites are far more valuable due to their advanced application potential. Smectites exhibit excellent swell properties and the highest cation exchange capacity (CEC). Smectites can be used as adsorbents, filler material, drilling mud, excipients, and plasticisers. Montmorillonite is a layered alumino silicate with a higher specific surface area. It is also the most abundant of the smectite clays. The main objective of the current study is to identify spatial and temporal variations in geochemical characteristics of the Murunkan clay deposit. In this on-going project, two boreholes were drilled nearly 1 km distance each other in the Murunkan Basin. One borehole reached a depth of 6.5 feet while the other just passed a depth of 4.0 feet. Samples were cut into 5 inches of each core. Geochemical characteristics of the Murunkan clay deposit were evaluated for 15 clay samples and a Sigma Aldrich montmorillonite sample (reference material) using Xray fluorescence (XRF), X-ray diffraction (XRD) and Fourier Transform Infra-Red (FTIR) analyses. XRF results indicate ~57% SiO2, ~19% Na2O, ~10% Al2O3, ~5% Fe2O3, ~2% CaO, ~2% MgO, ~1.5% K2O, and ~1% TiO2. FTIR spectra of analysed clay samples show transmittance bands matching with the standard data of kaolinite and montmorillonite. Similarly, XRD analysis also suggests the occurrence of clay minerals such as montmorillonite, illite, kaolinite, chlorite, muscovite and cookeite. Quartz and feldspar can also be detected as the major impurities in the Murunkan clay samples. However, no considerable spatial and temporal geochemical variations can be observed in this deposit. Therefore, the Murunkan clay deposit can be identified as a prospective area for further exploration. The future research works would focus to demarcate the boundary of clay deposit and quantify the volumetric estimation. Besides, value additional potential such as purification and possible industrial applications would be examined. Keywords: Murunkan clay, Montmorillonite, Value addition potential