Browsing by Author "Mendis, MS"

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item: Conference-Abstract
Evaluating the effectiveness of treatment solutions on blue stain fungi growth in pine wood plantations in Sri Lanka
(Department of Civil Engineering, University of Moratuwa, 2024) Rathuge, LR; Hewage, IS; Mendis, MS; Halwatura, RU; Pasindu, HR; Damruwan, H; Weerasinghe, P; Fernando, L; Rajapakse, C
The presence of blue stain fungi in pine wood plantations causes a significant challenge to the pine wood industry. Because of the visible discoloration due to the presence of fungi, it significantly reduces the market value of the wood. This study was conducted to explore the occurrence of blue stain fungi growth in pine wood plantations in Sri Lanka, with a focus on assessing the effectiveness of various wood treatment solutions. The research was conducted over six months, at a pinewood plantation in Bandarawela. The primary objective was to compare the effectiveness of different treatment solutions on the occurrence of blue stain fungi in treated versus non-treated wood samples. 27 wood samples prepared from freshly cut pine trees were used in this study. The samples were treated using four different solutions: two inorganic preservatives, Anti-blue and Anti-boron which are widely available in the market, and two innovative organic preservatives developed in Sri Lanka: Final Solution Without Mud (FSWOM) and Final Solution With Mud (FSWM). Samples were immersed in the solutions for 48 hours for the treatment, using the dipping method. To assess the impact of treatment timing, two sets of samples were prepared: one set was treated within 7 days of cutting, and another set within 7 to 14 days. To provide a baseline for comparison, a control set of non-treated samples was maintained. The results demonstrated that all treated samples showed significantly reduced blue stain fungi growth compared to the non-treated samples. Both inorganic preservatives, Anti-blue and Anti-boron, were highly effective in mitigating the blue stain fungi growth. Remarkably, the organic preservatives were also successful. FSWM was the most effective organic solution matching the performance of the commercially available inorganic preservatives. FSWOM, while slightly less effective than FSWM, still provided good protection against blue stain fungi, indicating the potential of organic solutions in wood preservation. It revealed that adding paddy field mud significantly enhanced the antifungal properties of these organic preservatives, approaching the level of effectiveness of the inorganic preservatives. Additionally, the study found that the timing of the treatment whether applied within 7 days or 7 to 14 days after cutting did not significantly affect the effectiveness of the treatment solutions. This implies that there is flexibility in the timing of treatment without compromising its effectiveness. The study concludes that both organic and inorganic preservatives are effective in mitigating blue stain fungi growth in pine wood. More specifically, the organic preservative FSWM provides an effective and environmentally friendly alternative to inorganic preservatives, thereby enhancing wood preservation techniques.
item: Conference-Abstract
Improvement of axial load capacity of large rectangular columns using cfrp method - case study
(2019) Pathirana, ISW; Mendis, MS
Columns are one of the most critical structural components of any structure. Column strengthening requirements are risen due to many reasons in relation to rehabilitation and improvements of existing buildings. Additional 4 floors were required to be added to a medium rise office building which was originally designed for 8 stories while it had been constructed up to its 4th floor. Detailed assessment of the structural capacity of the existing columns revealed that about 20% of axial load capacity improvement of selected ground floor columns was required to withstand the additional loads from the proposed additional floors. The strengthening of the existing columns was proposed to be done using carbon fiber reinforced polymer (CFRP). Preliminary CFRP design was carried out in accordance with the ACI.440.1R. The code’s limitations on the aspect ratio and the maximum face dimensions of columns had to be disregarded due to the shapes and dimensions of the real columns. Therefore, the proposed CFRP design was validated using a scale model column test and numerical model results obtained using ABAQUS. Selected columns of the building were strengthened using the proposed CFRP application and the building has been in operation for two years after successfully adding four new floors to it. This paper reports and discusses the outcomes of the case study on strengthening of different shape columns of this office building using CFRP.
item: Article-Full-text
Influence of grain distribution on orientation of saw cuts: Reference to heritage structures
(Elsevier, 2019) Mendis, MS; Halwatura, RU; Somadeva, DRK; Jayasinghe, RA; Gunawardana, M
Longitudinal arrangement of wood fibers are known as timber grains. It is one of the most important physical aspects of timber in applications. The properties differ along the grain and against the grain. Straight grains run parallel to the longitudinal axis of the wood. Meanwhile the cross grain deviates from the longitudinal axis as spiral and diagonal grains. This orientation has a high influence on the timber and affects physical properties during application. In order to study this, a detailed analysis was performed on Ambalam structures, a cherished heritage structure originated from the vernacular architecture in Sri Lanka. These structures are existing living proofs of vibrant construction materials with an exposed environment for more than 50 years. Badulla Ambalama,Padivitiya Ambalama, Panavitiya Ambalama, Karagahagedra Ambalama, Giruwa Ambalama and Rukula Ambalama were selected as case studies. The growth ring distribution of the exposed surfaces of the structural components were mapped using AutoCAD software. The results of overlapping and mapping the growth ring distribution of the specific timber helps to generate clues on size of the tree and sawing pattern of the wood log. The generated growth ring map revealed the sensitivity and the adequate knowledge in material manipulation utilized for specific structural components with respect to the load distribution. The Ambalam heritage structures have enlighten timber as an acceptable construction material with a respectable service life for tropical countries.
item: Conference-Full-text
Investigation on the mechanical property variation on timber caused due to the thermal and chemical modification
(IEEE, 2020-07) Sudeshika, DMP; Mendis, MS; Halwatura, RU; Weeraddana, C; Edussooriya, CUS; Abeysooriya, RP
Timber is a popular natural construction material since ancient time. Quality of timber varies with physical and mechanical properties. Timber modification techniques are used to improve durability and dimension stability of the timber. The aim of this research is to create a data base on mechanical property variation on timber caused due to the thermal and chemical modifications. Two distinct industrial surveys were conducted clusters-based and companies based survey to identify most abundantly utilized timber for structural applications and most abundantly utilized preservative techniques in Sri Lanka. Through the industrial survey results, three timber species were selected and specimens were prepared. Industrial survey concluded five major treatment methods; kiln dry,dipping,impregnation,brushing and spraying. Then prepared specimens were treated by the above timber modifications techniques. Compression parallel to grain and static bending test (central loading) were conducted according to BS 373: 1957 standard. According to test results, in Alastonia timber dipping & kiln dry and impregnation & kiln dry, in Rubber timber kiln dry, dipping & kiln dry and dipping and in Mango timber brushing and spraying modification techniques exemplified significant mechanical properties (compression parallel to grain,MOR (modulus of rupture) and elasticity) improvement
item: Conference-Full-text
Non-verbal communicative aspects of verandah in “walauwa” under uva province: a case study
(2018) Mendis, MS; Jayasignhe., S; Samarawickrama, S
Vernacular architectural built environments are bio climatically comfortable, effective spaces as means of achieving comfort. “Pila” is a sustainably designed built environment with a goal of long term sensitive humanization of vernacular Architecture. Together it mergers natural environmental conditions such as natural light, heat and ventilation is a significant manner. This multidisciplinary sustainable built environment; “Pila”, was introduced in the novel mode with the colonization known as “Verandah”. Caste system declared during Kandyan period, society composed with groups of people comprising diverse social levels. Under this norms, upper class or elites’ constructed a dwelling type “Walauwa”.Verandah is the preliminary element that these diverse social structure met. The fixed and semi fixed elements acts as an immediate transitional communicating non-verbally and logically. Uva province faced two Kandyan wars. Three case studies prevailed in Uva belongs to Last colonized British period creates an opportunity to interpret and compare the Verandah periodically. Detailing, materials, proportions and the user behavior was studied in depth on semi fixed elements of the Verandah and analyzed. The study will analytically conclude, how the semi-fixed elements, in depth towards furniture in Verandah non-verbally communicates the prevailed social structure with respect to Uva province.
item: Conference-Full-text
Prototyping a coating based on ancient technology: a case study in Sigiriya, Sri Lanka
(Department of Building Economics, 2024) Weerasekara, KMKD; Rathnayake, RMKM; Mendis, MS; Galabada, H; Jayasinghe, GY; Halwatura, RU; Sandanayake, YG; Waidyasekara, KGAS; Ranadewa, KATO; Chandanie, H
This paper presents a study on prototyping a coating based on ancient technology, specifically focusing on the techniques used in Sigiriya, an ancient rock fortress located in Sri Lanka. Sigiriya stands out for its remarkable paintings and innovative hydraulic systems, emblematic of an advanced ancient civilisation. Through an interdisciplinary approach merging archaeology, materials science, and chemistry, this research seeks to understand and replicate the coatings found on the Sigiriya paintings. By analysing the composition and properties of these coatings, a modern prototype was developed that mirrors the characteristics of the ancient coatings, offering insights into their longevity and preservation methods. The experimental emphasis of the research is on the production of a natural surface coating utilising wood apple gum and other natural extracts. The methods included coating formulation, application, and testing. There were five treatments in the study, each with different ratios (20%,40%,50%,60%, and 80%) of wood apple (Limonia acidissima) gum, Dorana (Dipterocarpus glandulosus) oil, sesame (Sesamum indicum)oil and Haldummala (Trachylobium verrucosum) mixes. This investigation explored the basic performance properties of coatings, looking closely at water resistance, viscosity, adhesion, pH levels, and aesthetic appeal. However, in treatment T1, the ratio of 20:80 of water: Dorana oil exhibited exceptional adhesion properties and displayed the maximum hardness level (8H). Some treatments also showcased promising indications of water resistance. The findings of this study hold the potential to significantly impact various sectors by providing eco-friendly alternatives, fostering innovation, creating cultural business prospects, and upholding traditional values.
item: Conference-Full-text
A Study on most abundantly utilized timber for structural application in Sri Lanka
(2019) Sudeshika, DMP; Mendis, MS; Halwatura, RU; Samarawickrama, S
Day to day demand for timber is increasing as a natural construction material due to its performance, stability, aesthetic, durability and been environmentally friendly. Different timber species have distinct characteristics and those are selected for different applications based on their characteristics. Value of timber varies with physical and mechanical properties and their quality can be improved by thermal and chemical modifications. An industrial survey was conducted to identify most abundantly utilized timber for structural applications in Sri Lanka. Industrial survey was conducted as two distinct surveys such as clusters-based survey and the company-based survey. Under cluster-based survey, 23 clusters; saw mills and treatment plants which were located in Moratuwa, Moratumulla, Koralawella, Pannipitiya and Swarapola were selected. For company-based survey, 3 companies in Colombo district following international standards contributing on large scale were selected. Research discussion conveys demand for application of imported timber has been increased because the availability of locally sourced structural timber is rare and expensive. Treated local timber has been popular due to its high durability resistance to the pests and their dimensional stability. From the industrial survey data, brushing, spraying, kiln drying; dipping and impregnation were identified as utilizing preservative techniques which have been using in Sri Lanka. Different species have been popular for different structural components in structural application. Based on cluster-based survey for the results revealed different timber species for different timber applications; rafters- Palu timber, beams- Kempass timber, reapers- Alastonia timber and door/ window frames- Jak timber were mostly utilized. And results from company based survey mostly utilized timber are Jak timber for rafters, Jak timber for beams, Ginisapu timber for rafters and variety timbers such as Ketakela, Mahogany, Jak and Teak for door window frames