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Publication Open Access Waste Polyethylene Reinforced with Coconut Fibers for Sustainable Construction: A Mechanical and Physical Property Evaluation Study(Dr D. Pylarinos, 2025-10-06) Dharmaratne, P. D; Galabada G.H; Malkanthi S.N; U.Halwatura R.This study evaluates the feasibility of using waste polyethylene as a construction material. To achieve this, a series of polymer composites were developed using waste Low-Density Polyethylene (LDPE) reinforced with coconut fiber (coir). The mechanical properties, including the tensile strength, flexural strength, impact strength, and elastic modulus, were assessed, along with the water absorption as a key physical property by following the ASTM standards. The composites were fabricated using the hand layup technique with varying coir-to-LDPE weight ratios and fiber lengths, followed by a hot-press machine manufacturing under controlled conditions. The results demonstrated that different fiber lengths and content levels influenced the mechanical properties, optimizing them at various configurations. A maximum tensile strength of 12.56 MPa was achieved using 40% coir content with 4 cm fiber length. The highest elastic modulus value of 0.46 GPa was achieved at 50% fiber content with 4 cm fibers. At 30% fiber content with 3 cm length, the maximum flexural strength value of 33.77 MPa was obtained. The impact strength reached its maximum value of 1.22 kJ/m² with 40% fiber content and 2 cm fiber length. The high water absorption exhibited by the composites, can be mitigated by applying waterproofing chemicals immediately after fabrication. It was found that the integration of fiber content and length affects the composite's properties. Depending on the required characteristics, appropriate fiber lengths and mix proportions can be selected, making these composites suitable for various applications in the construction industry. Additionally, proper waterproofing immediately after manufacturing the composite is proposed to enhance its performance as a construction material.Publication Open Access Influence of Laboratory Synthesized Graphene Oxide on the Morphology and Properties of Cement Mortar(MDPI, 2023-01) Ganesh, S; Thambiliyagodage, C; Perera, S. V. T. J; Rajapakse, R.K.N.DThe introduction of Graphene Oxide (GO), a nanomaterial, has shown considerable promise in improving the mechanical properties of cement composites. However, the reasons for this improvement are not yet fully understood and demand further research. This study aims to understand the effect of laboratory-produced GO, using Tour’s method, on the mechanical properties and morphology of cement mortar containing GO. The GO was characterized using Fourier-transform infrared spectroscopy, X-ray Photoelectron Spectroscopy (XRD), X-ray powder diffraction, and Raman spectroscopy alongside Scanning electron microscopy (SEM). This study adopted a cement mortar with GO percentages of 0.02, 0.025, 0.03, 0.035, and 0.04 with respect to the weight of the cement. The presence of GO in cement mortar increased the density and decreased the consistency and setting times. At the optimum of 0.03% GO viscous suspension, the mechanical properties such as the 28-day compressive strength, splitting tensile strength, and flexural strength were enhanced by 41%, 83%, and 43%, respectively. In addition, Brunauer–Emmett–Teller analysis indicates an increase in surface area and volume of micropores of GO cement mortar, resulting in a decreased volume of mesopores. The improvement in properties was due to increased nucleation sites, calcium silicate hydrate (CSH) density, and a decreased volume of mesopores.Publication Open Access INVESTIGATION MECHANICAL & DURABILITY PROPERTIES OF CRUMBED RUBBER CONCRETE CONTAINING RECYCLED CONCRETE AGGREGATE(SLIIT, 2022-02-11) Herath, H.M.V.K; Mendis, A. S. MThe concrete construction industry requires huge amount of natural resources. Currently natural resources are depleting while demand for concrete is increasing. Several studies are focused to solve this issue. The waste rubber has become a huge environmental issue worldwide. Researchers identified a sustainable way of reusing waste rubber by recycling it to Crumbed Rubber and partially replacing that for fine aggregate in concrete. However, with introduction of this crumbed rubber to concrete, the compressive strength of developed concrete was decreased. Therefore, the main aim of this research is to improve compressive strength in Crumbed Rubber Concrete using recycle concrete aggregate. Other than that, some fresh properties, mechanical & durability properties were investigated. 15 percent of replacement of fine aggregate by rubber has been identified as an optimum replacement level by other studies. Therefore, this study was conducted for 15% volume based fine aggregate replacement. As recycle aggregate act as a cementitious binder, it was added in 10,15,20,30 percent of weight basis for cement. The w/c ratio was kept constant at 0.57. Maximum 10 mm aggregate was used in the study. The crumbed rubber replacement resulted in 60 percent decrement in compressive strength and recycled aggregate in all levels resulted in a higher compressive strength than rubber-only concrete but got optimum increment in 20 percent and starts to decrease. Same as compressive strength, splitting tensile, flexural strength increased to optimum values with 20 percent of recycled aggregate. The available design codes were used to calculate theoretical values using experimental values to investigate adequacy of these mixes. The investigate revealed that available standard guidelines cannot be used to predict the behavior of crumbed rubber concrete containing recycled concrete aggregate. This study proves that addition of recycle aggregate to crumbed rubber concrete improves its strength. However, the durability and dynamic properties of this developed concrete needs to be investigated.Publication Embargo Effects of free edges and vacancy defects on the mechanical properties of graphene(IEEE, 2014-08-18) Dewapriya, M. A. N; Rajapakse, R. K. N. DDefects are unavoidable during synthesizing and fabrication of graphene based nanoelecromechanical systems. This paper presents a comprehensive molecular dynamics simulation study on the mechanical properties of finite graphene with vacancy defects. We characterize the strength and stiffness of graphene using the concept of surface stress in three-dimensional crystals. Temperature and strain rate dependent atomistic model is also presented to evaluate the strength of defective graphene. Free edges have a significant impact on the stiffness; the strength, however, is less affected. The vacancies exceedingly degrade the strength and the stiffness of graphene. These findings provide a remarkable insight into the strength and the stiffness of defective graphene, which is critical in designing experimental and instrumental applications.Publication Embargo Influence of temperature and free edges on the mechanical properties of graphene(IOP Publishing, 2013-08-12) Dewapriya, M. A. N; Phani, A Srikantha; Rajapakse, R. K. N. DA systematic molecular dynamics simulation study is performed to assess the effects of temperature and free edges on the ultimate tensile strength and Young's modulus of a single-layer graphene sheet. It is observed that graphene sheets at higher temperatures fail at lower strains, due to the high kinetic energy of atoms. A numerical model, based on kinetic analysis, is used to predict the ultimate strength of the graphene under various temperatures and strain rates. As the width of a graphene reduces, the excess edge energy associated with free edge atoms induces an initial strain on the relaxed configuration of the sheets. This initial strain has a greater influence on the Young's modulus of the zigzag sheet compared with that of the armchair sheets. The simulations reveal that the carbon–carbon bond length and amplitude of intrinsic ripples of the graphene increases with temperature. The initial out-of-plane displacement of carbon atoms is necessary to simulate the physical behaviour of a graphene when the Nosé–Hoover or Berendsen thermostat is used.