Browsing by Author "Fernando, J.A.K.M."

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    Development of a Composite Board by Mixing Cement, Coir Fiber and Calcium Carbonate
    (Uva Wellassa University of Sri Lanka, 2013) Jathunarachchi, P.N.; Withanage, N.S.; Fernando, J.A.K.M.
    Coir fiber products have a great potential in domestic and international market in view of the world trend towards natural products. Now a days coir fiber reinforced cement boards are becoming more popular than harmful synthetic fiber reinforced cement boards. Their natural abundance, relative cheapness and instantaneous replacing ability are the strongest arguments to utilize them in the construction industry in Sri Lanka. In the Acetylene plant, calcium carbonate is the waste material. Due to its excellent filling ability and the availability, it can be used in composite board manufacturing. For the development of the coir industry and to add value to the wasting coir surplus and calcium carbonate waste from acetylene plant, it is required to investigate the possibility of using coir fiber and calcium carbonate in composite board manufacturing. This research was aimed at developing a coir fiber reinforced composite board by mixing cement, coir fiber and calcium carbonate via the determination of weight fraction of the constituents of the boards. In addition to that, the effect of various coir fiber types (Bristle fiber, Mattress fiber and Baby fiber) as well as various calcium carbonate ratios (10%, 20% and 25%) on board properties such as dry weight, thickness, density, water absorption and flexural strength were also determined. Then the possibility of using these composites in ceiling sheet manufacturing was studied. Methodology Three types of coir fibers (Bristle fiber, Mattress fiber and Baby fiber), Calcium Carbonate (CaCO3) and Ordinary Portland cement (OPC) were obtained locally. Calcium carbonate precipitates were ground and sieved using 0.5 mm sieve to obtain the calcium carbonate in powder form. Then bristle fiber and the mattress fiber were cut into 2 cm length in pieces. Preliminary studies were conducted to find out the suitable composition for the development of composite board using cement, coir fiber andcalcium carbonate. In the preliminary trials ten different composites were manufactured and evaluated its weight and other physical properties and it was observed that the composite C34B was not acceptable condition. Accordingly nine composite mixtures were selected for further testing of the physico-mechanical properties. Compositions of mixtures were given in table no 1. Ordinary Portland cement and calcium carbonate in various ratios were manually mixed with water and also coir fiber. The mixing of these ingredients was continually done until the cement, calcium carbonate and fiber paste were uniformly distributed. Then the mixture was spread out in a metal frame placed on a polythene sheet to form a board using mason’s trowel. The board was inserted in between the two plates of hydraulic press machine and it was densified by compressing it to a desired thickness using a hydraulic press. The pressure was maintained for 24 hours. The boards were removed from the press after 24 hours and soaked in the water for 7 days for curing and conditioning. The cement: calcium carbonate ratios were varied in 400:160,400:120,400:50 while cement and CaCO3 to fiber ratio was kept at a constant (10%) and the fiber types were also changed. The amount of water was fixed at 400ml per board.
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    Identification of Retting Enhancing Microbial Strains in Coconut Fibre Extraction
    (Uva Wellassa University of Sri Lanka, 2019-02) Thilakarathna, H.M.N.P.; Fernando, J.A.K.M.; Dharmarathne, T.T.D.; Senavirathna, A.M.W.K.
    Coir fibre is extracted from coconut (Cocos nucifera L.) husk. Natural retting process needs at least 3 months period for obtaining good quality bristle fibre. This study was carried out to reduce the retting time by introducing previously identified pectin and cellulose degrading microbial strains from bio chemical tests. For this experiment, coconut variety of CRIC60 from Bandirippuwa estate in Lunuwila was used. Retting experiments were carried out using five different combinations of microbes namely, Serratia rubidea, Bacillus safensis, Bacillus thuringiensis and Staphylococcus sciuri. The control was water. The experiment was carried out for two months. The coconut husk samples were collected by two week intervals and Ceylon drum machine was used for the fibre extraction. The percentages of bristle fibre and its qualities were analyzed. The ret liquor samples were also analyzed for pH and Electrical Conductivity. Tensile strength (118.39±1.9 N mm-2), breaking load (3.27±0.36 N), average length (127.11±2.39 mm) and fineness (27.26±3.33 g km-1) of initial sample were found to be increased to 145.48±3.97 N mm-2, 4.35±0.28 N, 152.01±2.52 mm and 57.29±1.31 g km-1, respectively with the treatment of coconut husks with Staphylococcus sciuri, Serratia rubidea, Bacillus safensis, Bacillus thuringiensis mixture for 4 to 8 weeks. Further, impurities (%) was reduced from 3.07±0.25 to 1.06±0.20 with this treatment. These values were satisfied with SLS Standards. Fibre percentage and the quality of ret liquor indicated by pH and Electrical Conductivity were also increased. Good quality bristle fibre can be obtained from coconut husks by treating with Staphylococcus sciuri, Serratiarubidea, Bacillus safensis, Bacillus thuringiensis consortium for 4-8 weeks.