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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Effect of microfibrillar cellulose on concrete equivalent mortar  fresh and hardened properties / Inverkan av mikrofibrillär cellulosa på egenskaperna hos betongekvivelent bruk i dess färska och hårdnade tillstånd

Nilsson, Jonas, Sargenius, Peter January 2011 (has links)
A pilot project in 2010, conducted at CBI, showed the capacity for pulp, micro fibrilars from the forest industry to act as Viscosity Modifying Agent (VMA) in concrete. This project was, however, too limited to find answers for optimal use of this kind of material. The forest industry company Stora Enso wants to find out if their pulp can be used in concrete in order to somehow improve its properties. Two micro fibrilar suspensions have been tested. The tested fibrils are in two sizes, the finer material named MFC1 has undergone more homogenization than the course material named MFC2. The fibrils have been evaluated in regard to how the fibrils react with mortars in both its fresh and hardened state. Tests have been conducted on the use of concrete equivalent mortars with a maximum aggregates size of 4 mm. Two water-cement-ratios have been used in the tests, 0.45 and 0.60. Three different fibril dosages have been tested, 1, 2 and 3 kg/m³. The results of these trials of cellulose fibrils has been evaluated in respect of rheology, compressive strength, flexural strength, cracking, shrinkage, water capillary porosity, anti-wash out resistance (underwater concrete) and as a possible surface coverage. The results from the trials, conducted in this report, show that an increased dosage of fibrils leads to an increased plastic viscosity. The fibrils appear to have no effect on the flexural- and compressive strength, and no effect on the shrinkage of the test specimens. According to our results it is not advisable to use the fibrils for the purpose of acting as an agent for anti-washout resistance, or as a surface coverage.   The work have been performed at Swedish Cement and Concrete Research Institute, CBI, in Stockholm in the spring of 2011. CBI is an institution whose mission is to create, apply and disseminate knowledge in the concrete and rock area. / Ett tidigare pilotprojekt har under 2010 utförts på CBI, och där undersöktes möjligheten för cellulosafibrer från skogsindustrin att fungera som Viscosity Modifying Agent (VMA) i betong. Utrymmet i detta projekt var dock för begränsat för att finna svar för optimal användning av denna typ av material. Nu vill skogsindustriföretaget Stora Enso ta reda på om massa från deras träprodukter kan användas i betong, för att på något sätt förbättra dess egenskaper. Vi har därför provat suspensioner innehållande två olika fraktioner av cellulosafibriller. De testade fibrerna finns i två storlekar, det finare materialet heter MFC1 och har genomgått med homogenisering än det grövre materialer som heter MFC2. Dessa två typer har tillsats i bruk och utvärderats i hur de reagerar i både brukets färska och dess hårdnade tillstånd. Testerna har genomförts på bruk med en maximal ballaststorlek på 4 mm. Två vct-nivåer har använts i försöken, 0,45 och 0,60. Tre olika fibrilldoser har prövats, nämligen 1, 2 och 3 kg/m³ fibriller. Resultaten från dessa försök av cellulosafibriller har utvärderats med avseende på reologi, tryckhållfasthet, böjhållfasthet, sprickbildning, kapillaritet, krympning, anti-urvaskning och som möjlig ytbetäckning.   De tester som har genomförts visar att med ökad dos fibriller ökar den plastiska viskositeten. Fibrillerna visade sig inte ha någon effekt på böj- eller tryckhållfasheten, samt ingen effekt på krympning av provkropparna. Testerna visar att fibrillerna inte heller agerar med någon possitiv effekt som anti-urvaskningsmedel, eller som ett täckande ytskikt.   Försöken har genomförts vid CBI Betonginstitutet i Stockholm mellan 21 mars och 8 juli år 2011.CBI är en institution vars uppdrag är att skapa, tillämpa och sprida kunskap inom betong och bergområdet.
2

Structural Properties of ICLT Wall Panels Composed of Beetle Killed Wood

Wilson, David Edward 06 June 2012 (has links) (PDF)
Interlocking Cross Laminated Timber (ICLT) wall panels are a new wood construction product similar to Cross Laminated Timber panels. Besides being an innovative structural system, they also utilize beetle killed timber from many of the forests that have been devastated by the Mountain Pine Beetle. Three tests were performed on three ply ICLT panels measuring 8 feet (2.44m) wide, 8 feet (2.44m) tall and 8.5 inches (21.6cm) thick to determine the racking, flexural and axial strengths of the wall panels. After each test was performed the walls were disassembled and investigated for cause of failure. Using the data from the tests as a benchmark, simple analytical models to predict the design capacities of the walls for racking, flexural, and axial strengths were established. The analytical models for racking strength, flexural strength and axial strength predicted reasonably well the measured strength values. Additional testing is necessary to increase the available database, further validate the analytical models developed, better understand the structural performance of ICLT panels, and establish acceptable design methodology for ICLT wall panels.

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