http://repo.lib.jfn.ac.lk/ujrr/handle/123456789/109 2026-04-08T08:27:44Z 2026-04-08T08:27:44Z Somarathna, H.M.C.C. Raman, S.N. Mohotti, D. Mutalib, A.A. Badrie, K.H. http://repo.lib.jfn.ac.lk/ujrr/handle/123456789/10043 2024-01-16T05:36:44Z 2021-01-01T00:00:00Z

Title: Behaviour of concrete specimens retrofitted with bio-based polyurethane coatings under dynamic loads Authors: Somarathna, H.M.C.C.; Raman, S.N.; Mohotti, D.; Mutalib, A.A.; Badrie, K.H. Abstract: Experimental investigationwasconductedusingconcretespecimenstoassesstheeffectivenessofbiobasedpolyurethane(PU)coatingsynthesizedfrompalmkerneloilinenhancingthedynamicmechanical responseofconcretespecimensunderquasi-staticanddynamicloads.Thedynamicloadingcondition wassimulatedbyconductingthree-pointbendingtestsatastrainrateof0.067s 1,andsimultaneously, under quasi-static loading(strainrateof0.00033s 1)conditions .The application of PU layer(s)(either on the impact face, reface ,or on both faces of the concrete specimens)increases the dynamic resistance of theconcreteelement,whichcanbeenhancedbyincreasingcoatingthicknessoneitherfaceoftheconcreteelement.Underdynamicconditions,with10%of total coating thickness compared to the beam depth, strainduringultimatefailure,andstrainenergydensitywereenhancedsignificantlywithmarginalenhancementintheultimateflexuralstrength.PUcoatingdoesnotdebondduringultimatefailure of the test specimens which implies good adhesion characteristics, and even with minimum coating thickness(2.5%),drasticfragmentationeffectscanbereduced.Bio-basedPUisagreenmaterialandapplicationof PU coating provides available and sustainable technique for protecting concrete structures against dynamic loads.

2021-01-01T00:00:00Z Suloshini, S. Ranathunga, A.S. Kulathilaka, S.A.S. Gunawardana, W.B. Mapa, M.M.S.T.M. http://repo.lib.jfn.ac.lk/ujrr/handle/123456789/10018 2023-12-29T06:39:03Z 2022-01-01T00:00:00Z

Title: Utilization of Bottom Ash for Clay Mine Rehabilitation Authors: Suloshini, S.; Ranathunga, A.S.; Kulathilaka, S.A.S.; Gunawardana, W.B.; Mapa, M.M.S.T.M. Abstract: Attheendofminingactivities,claymineswereabandonedduetothecost andnon-availabilityoffillingmaterials.Theseabandonedclayminescauseadverse environmentalandsocialimpacts.Inaddition,largequantitiesofbottomash(BA) aregeneratedasaby-productofcoalcombustionprocess.ThisBAisdisposedby opendumpinginthelands,whichcreatessevereenvironmentalpollution.Therefore, conductedresearchonutilizationofBAforminerehabilitationisbeneficial.The mainfocusofthisresearchisapplicabilityofBAgeneratedfromLakvijayapower plant,SriLankaasapotentialbackfillmaterialandasoilamendmentduringtheclay minerehabilitation.Initiallytestswereconductedtoinvestigatethebasicproperties ofBA.Next,chemicalcompositionofBAwasanalysedtoselectthesuitablecrops forvegetation.FurtherpH,electricalconductivityandwaterholdingcapacitywere checkedandmicrostructuralmorphologyofBAwasdeterminedthroughScanning ElectronMicroscope.TheresultsshowedthatBAhasgoodengineeringproperties andthepotentialtoimproveagronomiccharacteristicsofsoil.Ithasbetterwater holdingcapacityandpermeability.BAcanadjustsoilpHtoadesirableplantgrowth range.AsBAhasaveryporousstructure,therootsystemcaneasilydevelopand helpstouptakenutrientsbytheplant.However,aconsiderablepercentageoftrace metalsisaccumulatedinBAwhichwillincreasethebioavailabilityofsometrace metalstolevelsthatposesrisktohuman.Thus,investigationswerecarriedoutto identifytheheavymetalconcentrationinleachateofBAusingcolumnleachingtest. ResultsshowedthatleachabilitypotentialoftracemetalsinBAdoesnotexceedthe allowablelimits.

2022-01-01T00:00:00Z Chuang, L. Krishnya, S. Ogino, M. Owaki, E. Elakneswaran, Y. http://repo.lib.jfn.ac.lk/ujrr/handle/123456789/10014 2023-12-29T05:42:55Z 2022-01-01T00:00:00Z

Title: Investigating the hydration characteristics of a new composite cementitious binder containing of slag and calcite Authors: Chuang, L.; Krishnya, S.; Ogino, M.; Owaki, E.; Elakneswaran, Y. Abstract: The influence of the filler content, filler fineness and water to powder ratio (W/P) on hydration kinetics and microstructure behaviour of a new clinker-free material made of calcium hydroxide, blast furnace slag (BFS), calcite and expansive agent are explored in this study. The hydration characteristics of the proposed material were investigated by multiple experimental programmes including X-ray diffraction (XRD), TG-differential thermal analysis (DTA), selective dissolution measurement and mercury intrusion porosimetry (MIP). The experimental results revealed that slag reaction degree is enhanced by increasing the filler content and fineness of the filler in high W/P ratio. However, the filler fineness does not show significant improvement in the hydration degree of slag with low W/P ratio in later curing period due to the reduced amount of available water for the hydration reaction. Another interesting finding of this study is that the hemicarboaluminate which is thermodynamically unstable than monocarboaluminate, stably formed even at the later age of hydration reaction in the presence of calcium carbonate. The amended thermodynamic model also well agreed with the tendency of the experimental results in terms of hydration products and porosity of the hardened matrix as a function of curing period.

2022-01-01T00:00:00Z Krishnya, S. Herath, C. Elakneswaran, Y. Gunasekara, C. Law, D.W. Sujeeva, S. http://repo.lib.jfn.ac.lk/ujrr/handle/123456789/10013 2023-12-29T05:38:08Z 2022-01-01T00:00:00Z

Title: Modeling of hydration products and strength development for high-volume fly ash binders Authors: Krishnya, S.; Herath, C.; Elakneswaran, Y.; Gunasekara, C.; Law, D.W.; Sujeeva, S. Abstract: Partial replacement of cement using fly ash, as an environmentally friendly approach, has gained increased attention in construction practice. The realistic prediction of microstructure and mechanical properties of fly ash blended cement paste is therefore noteworthy for many practical applications including selection of construction material and their appraisal of design. In this research work, an integrated framework is proposed and demonstrated for predicting the hydration products and compressive strength of high-volume fly ash binders. The prediction framework is designed to have multiple stages. For computing the hydrates of blended cement paste, a coupled hydration model with thermodynamic modelling is developed. A hierarchical model that captures the development of the paste via multiple levels (from C-S-H globules to blended cement paste) is used subsequently to predict the compressive strength as a function of hydration period. Here, unlike previous works, the formation of C–S–H is realistically modelled by distinguishing it into low- and high-density C–S–H. A series of experiments (including XRD Rietveld analysis, thermo gravimetric analysis, selective dissolution, mercury intrusion porosimetry and compression tests) are performed; hence the predictability of the developed work is assessed by comparing the predicted results with experimental data. A very good agreement is seen between the predicted results (hydration products, pore volume and compressive strength) and experimental results, indicating that the proposed model can be applicable to the high-volume fly ash cement paste to reliably capture the hydrates and compressive strength. It is further noted that with an increase in fly ash replacement ratio, the capillary porosity increases, while the reaction rate and compressive strength decrease.

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