Orientador: Wesley Jorge Freire / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Agricola / Made available in DSpace on 2018-08-03T23:55:49Z (GMT). No. of bitstreams: 1 MesaValenciano_MarthadelCarmen_D.pdf: 5926517 bytes, checksum: c5fdeb8ea15fe2ab078f58e162b8797d (MD5) Previous issue date: 2004 / Doutorado / Construções Rurais e Ambiencia / Doutor em Engenharia Agrícola

In this thesis, the development of mechanical properties and structure of latex modified cementious materials during hydration was studied. Latex modified materials are composites of inorganic cement (portland cement) and organic polymer latex. Preparation, processing and fabrication of the polymer cement material based on portland cement was optimized with aim to reach the most compact structure of the product with the finest mechanical characters. The experimental part was pointed to observe influence of the type and amount of polymer latex with focus on mechanical characters and hydration kinetics with given filling as well as without it. In presented work, the possibility of compaction of the material by high-shear mixing within twin-roll mixer (the prototype for production of MDF composite) was verified. The second part of the labor was aimed to analysis of prepared polymer-cementitious material. For determination of influence of batching of added polymer latex on hydration of cement paste the thermal analysis (DTA/TGA) and infrared spectroscopy of composite was done. At last the microscopic observation by optical microscope was carried.

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.

Aim: The aim of the present study was to evaluate how the material KATANA ™ Zirconia YML is affected in strength depending on two different sintering programs. The evaluation of the strength was made by means of a biaxial flexural strength test.   Material and method: A total of 48 test specimens, 32 specimens were produced by KATANA ™ Zirconia YML and 16 specimen cups that formed the control group, by KATANA ™. Zirconia UTML. The specimens were designed as circular disks and were placed in two different layers in the disk, between Enamel-Body 1 and Body 2-Body 3. The specimens were divided into two subgroups of which 24 specimens were quickly sintered and the remaining (n = 24) specimens were conventionally sintered and the strength was evaluated with a biaxial flexural strength test.   Results: The highest mean value for the biaxial flexural strength test was shown by the test group which was high-speed sintered, with placement in Body 2 - Body 3. This was significant in comparison with other groups (p> 0.001) in addition to conventional sintered with the same placement in the disk. Both control groups showed low mean values ​​in comparison with the test groups, control group K (414 MPa) as the lowest in comparison with all other groups. When comparing the two control groups S and K, no significant difference was shown.   Conclusion: The bending strength varies depending on which layers are loaded regardless of fast and conventional sintering. The sintering parameters are significant for the bending strength. / Syfte: Syftet med föreliggande studie var att utvärdera hur materialet KATANA™ Zirconia YML påverkas i hållfasthet beroende av två olika sintringsprogram. Utvärderingen av hållfastheten gjordes med hjälp av ett biaxialt böjhållfasthetstest.   Material och metod: Totalt framställdes 48 provkroppar, 32 stycken framställdes av KATANA™ Zirconia YML och 16 provkoppar som utgjorde kontrollgrupp, av KATANA™. Zirconia UTML. Provkropparna var utformade som cirkulära diskar och dem placerades i två olika skikt i disken, mellan Enamel-Body 1 och Body 2-Body 3. Provkropparna delades in i två undergrupper varav 24 provkroppar snabbsintrades och resterande (n=24) provkroppar sintrades konventionellt och hållfastheten utvärderades med ett biaxialt böjhållfasthetstest.   Resultat: Högst medelvärde för det biaxiala böjhållfasthetstestet uppvisade testgruppen som snabbsintrats, med placering i Body 2 – Body 3. Detta var signifikant i jämförelse med övriga grupper (p > 0,001) förutom konventionellt sintrat med samma placering i disken. Båda kontrollgrupperna uppvisade låga medelvärden i jämförelse med testgrupperna, kontrollgrupp K (414 MPa) som lägst i jämförelse med alla övriga grupper. Vid jämförelse mellan de två kontrollgrupperna S och K uppvisades inte någon signifikant skillnad.   Slutsats: Böjhållfastheten varierar beroende på vilka skikt som belastas oavsett snabb- respektive konventionell sintring. Sintringsparametrarna är betydande för böjhållfastheten.

Syfte Syftet med föreliggande studie var att undersöka böjhållfastheten hos IPS e.max CAD före och efter termocykling med 10 000 respektive 15 000 cykler. Material och metod Trettio provkroppar framställdes från fem stycken IPS e.max CAD LT-block. Provkropparna var indelade i två testgrupper (GT10 och GT15), och en kontrollgrupp (GK), á 10 provkroppar i varje. Provkropparna utformades enligt måtten L 17,9 ± 0,03 mm x B 2,5 ± 0,03 mm x H 2,5 ± 0,03 mm. Samtliga provkroppar kristalliserades och grupp GK förvarades i rumstemperatur, resterande två grupper, GT10 och GT15 termocyklades i 10 000 respektive 15 000 cykler.Därefter utfördes ett trepunkts böjhållfasthetstest. Resultaten analyserades med One-way ANOVA, Tukey’s test med signifikansnivån α= 0,05 i statistikprogrammet SPSS. Resultat Resultaten visade att det inte fanns någon signifikant skillnad mellan grupp GK och GT10 (p>0,05) respektive mellan grupp GT10 och GT15 (p>0,05). Grupp GT15 hade högst medelvärde (516 MPa) och grupp GK hade lägst medelvärde (450 MPa). Signifikant skillnad fanns mellan grupp GK och GT15 (p<0,05). Grupp GT15 hade en signifikant högre böjhållfasthet (~470-637 MPa) jämfört med grupp GK (~406-494 MPa). Slutsats Inom föreliggande studies begränsningar kan följande slutsatser dras: Termocykling med 10 000 cykler påverkar inte böjhållfastheten, däremot ger ökat antal cykler (15 000) högre böjhållfasthet. / Purpose  The purpose of the present study was to investigate the flexural strength of IPS e.max CAD beforeand after thermal cycling with 10,000 and 15,000 cycles, respectively.  Material and method  Thirty specimens were prepared from five IPS e.max CAD LT blocks, divided into two test groups (GT10 and GT15), and one control group (group GK) (n=10). The specimens were designed with the dimensions L 17.9 ± 0,03 mm x W 2.5 ± 0,03 mm x H 2.5 ± 0,03 mm. All specimens were crystallized and group GK was kept in room temperature, the remaining two groups, GT10 and GT15 were thermocycled with 10,000 and 15,000 cycles respectively. A three-point flexural strength test was performed. The results were analyzed with One-way ANOVA, Tukey's test with a significance level α = 0.05 in the statistical program SPSS.  Results  The results showed that there was no significant difference between groups GK and GT10 (p> 0.05), and between groups GT10 and GT15 (p> 0.05). It was also observed that group GT15 had the highest average (516 MPa) and group GK had the lowest average (450 MPa). There was a significant difference between groups GK and GT15 (p <0.05). Group GT15 had a significantly higher flexural strength (~ 470-637 MPa) compared to group GK (~406-494 MPa).  Conclusion  Within the limitations of the present study, the following conclusions can be drawn:Thermal cycling comprising 10,000 cycles do not affect the flexural strength, however, increasing the number of cycles (15,000) will give higher flexural strength.

Indiana University-Purdue University Indianapolis (IUPUI) / Objectives: A new technology has been introduced into the field of dental resin composites that professes to enhance light-curing efficiency. Rapid amplified photopolymerization (RAP) initiator technology has not yet been fully compared with resin composites with conventional initiators such as camphorquinone (CQ). The purpose of this study was to compare and contrast the effects of this novel technology (RAP) on properties of two light-cured resin composites. Flowable (EFQ) and microfilled (ESQ) experimental composites were fabricated and supplied from Tokuyama Dental with (w/RAP) and without RAP (w/o RAP). The flexural strength (MPa) and flexural modulus (MPa) were obtained using a three-point bending apparatus (Sintech Renew 1123, Instron Engineering Corp., Canton, MA). Polymerization stress curves were created using a tensometer (American Dental Association Health Foundation, NIST, Gaithersburg, MD) which were then used to calculate the maximum stress rate. Finally, the degree of conversion was measured using infrared spectroscopy (Jassco FT-IR spectrometer, Model: 4100, Jasco Corporation, Tokyo, Japan). When evaluating the flexural strength, the peak stress for EFQ w/RAP was significantly higher than EFQ w/o RAP (p = 0.0001). This was statistically not significant for the ESQ group, even though ESQ w/RAP did have a higher peak stress then ESQ w/o RAP (p = 0.28). The interaction between resin type and RAP was not significant when evaluating the flexural modulus (p = 0.21). Formulations with RAP had a significantly higher flexural modulus then w/o RAP (p = 0.0001). Experimental resins with RAP had significantly higher maximum stress rates than those w/o RAP when evaluating polymerization stress (p = 0.0001). Finally, groups w/ RAP appeared to have a higher degree of conversion than groups without (p = 0.0057). This study showed that the experimental composites with RAP had greater mechanical properties than those without. Unfortunately, the increase in polymerization stress causes concern clinically due to the chance of leakage at the restoration/tooth interface. One of the main potential disadvantages of this new RAP technology is an increase in the polymerization stress. Deciding if this amount of polymerization stress is clinically acceptable is yet to be accomplished.

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.

No description available.

In this study, the mechanical properties of a fiber-reinforced cementitious composite (FRCC) were derived for specimens fabricated using two different methods of casting: conventional cast construction and pump-driven extrusion. Through the extrusion process, fibers are more likely to be oriented along the length of the member being cast and will therefore be more efficient since they are aligned parallel to the tensile stresses produced in flexure testing. The FRCC employed 0.5% and 1% polyvinyl alcohol (PVA) fiber reinforcement by volume. The flexural properties of FRCC were determined using four-point bend tests according to a modified ASTM C1609. Calculations included the modulus of rupture (MOR) and flexural toughness based on load-deflection curves. The fracture properties of FRCC were determined by using three-point bend tests on the same design but having notched beams using the two-parameter fracture model (TPFM). Calculations included the Mode I critical stress intensity factor (KIC), the critical crack tip opening displacement (CTODc), the strain energy release rate (GIC), and the total fracture energy (GF). The results show that enhanced ductility and post-peak behavior are achieved in concrete to which fibers have been added, as has been demonstrated in other studies, although this study further demonstrated how preferential fiber alignment produced via an extrusion can enhance fracture and flexural properties of cementitious composites. / Master of Science / Fiber-reinforced cementitious composite (FRCC) is a type of cementitious composite that contains fibers that are added to the mixture to improve its strength, durability, and ductility. One of the key factors of FRCC that affects its mechanical properties is the fiber alignment. Extrusion can be used as a method to preferentially align the fibers in order to maximize the benefit of fibers. Extruded FRCC can be pumped through a nozzle, making fiber alignment a convenient option for construction projects where traditional concrete placement methods would be difficult. One of the main benefits of aligning fibers in pump-extruded FRCC is that it can improve cementitious composites' fracture and flexural toughness. Fracture toughness refers to the ability of a material to resist crack propagation, while flexural toughness refers to its ability to withstand bending. By adding fibers to the mixture, the fibers act as reinforcement and help to distribute stress more evenly throughout the material, leading to increased strength and ductility. Furthermore, the alignment of fibers within the mixture also plays a critical role in the fracture and flexural strength of the material. Research has shown that when fibers are aligned in a specific direction, they can improve the tensile strength of the concrete and decrease the likelihood of crack propagation. This can be especially useful in structures that are exposed to seismic activity or long-lasting heavy loads. Overall, the use of pump extrusion-based method as a fiber alignment for FRCC can significantly improve the fracture and flexural strength of concrete. This makes it an attractive option for construction projects that require strong and durable members.

Diante da evolução da composição das resinas compostas e do lançamento de compósitos do tipo bulk fill, faz-se necessário o estudo do desempenho dessa nova classe de materiais. Para isso, o presente estudo teve como objetivo avaliar propriedades como grau de conversão (GC) , dureza Knoop (KHN), resistência à flexão (RF) e tenacidade à fratura (KIC) de sete compósitos bulk fill (EverX Posterior, EXP; Filtek Bulk Fill Flow, FBFF; Fill-Up!, FU; SonicFill, SF; Surefil SDR, SDR; Tetric EvoCeram Bulk Fill, TECBF; Venus Bulk Fill, VBF) e um compósito nanohíbrido convencional (Charisma Diamond, CD). De forma complementar, foi realizado tratamento térmico a 170 °C por 10 minutos para melhor compreensão do comportamento desses materiais quanto ao potencial de conversão e à indução de tensões na interface carga/matriz. A avaliação do GC (n=3) foi realizada através de espectroscopia FTIR, a leitura da dureza Knoop foi realizada nas superfícies do topo e da base (n=3), e os ensaios de RF de três pontos (n=10) e KIC (n=10) em máquina de ensaios universais. Os resultados obtidos foram submetidos à analise de variância (complementados pelo teste de Tukey) ou teste Kruskal-Wallis, com nível de significância de 5%. A análise do GC (%) revelou diferença entre os materiais testados, sendo que todas as resinas bulk fill apresentaram valores maiores que a resina convencional: SF (75,7) > VBF (66,7) = EXP (66,4) = SDR (62,8), sendo esta também semelhante a FU (60,0); FU, TECBF (56,6), FBFF (56,6) e CD (54,5) apresentaram conversão semelhante. Os valores de KHN variaram de acordo com o material e com a superfície: apenas SF apresentou KHN semelhante (na superfície do topo) a CD, entretanto não foi possível realizar a leitura da superfície da base deste último material; SF, TECBF e FBFF apresentaram valores de KHN diferentes nas superfícies topo e base; EXP, FU, SDR e VBF mantiveram os valores de dureza do topo semelhantes à superfície da base. Para a RF (MPa), os resultados variaram de acordo com o material: EXP (122,54) = SF (101,09) = CD (99,15), sendo estes dois últimos semelhantes a FU (83,86) e TECBF (82,71), os quais não diferiram da resina SDR (65,18); esta última também mostrou comportamento semelhante a FBFF (60,85) e VBF (59,90). Quanto ao KIC (MPa.mm0,5), EXP (3,35) apresentou o maior valor, semelhante a SF (2,42), que por sua vez também foi igual ao compósito convencional CD (2,01); CD apresentou KIC semelhante a SDR (1,74); SDR = VBF (1,59) = TECBF (1,57); TECBF, FU (1,54) e FBFF (1,37) apresentaram valores semelhantes. Na dependência do material, o tratamento térmico aumentou os valores dos parâmetros estudados, apontando limitações da reação de polimerização dos compósitos estudados. Com base nos resultados obtidos, podese concluir que: resinas bulk fill apresentam elevado GC, superior à resina convencional estudada; a nova classe de materiais restauradores é capaz de polimerizar em profundidade e alguns materiais apresentam KHN semelhantes no topo e na base de espécimes de 4 mm de profundidade; RF e KIC variaram de acordo com o material, e o compósito EXP apresentou os maiores valores para ambos os testes. / Facing the evolution of the resin composites and the release of the bulk-fill composite type, it is necessary to study the performance of this new class of materials. For this, the present study aimed to evaluate properties such as degree of conversion (DC), Knoop hardness (KHN), flexural strength (FS) and fracture toughness (KIC) of seven bulk-fill composites (EverX Posterior, EXP; Filtek Bulk Fill Flowable, FBFF; Fill-Up!, FU; SonicFill, SF; Surefil SDR, SDR; Tetric EvoCeram Bulk Fill, TECBF; Venus Bulk Fill, VBF) and a conventional nanohybrid composite (Charisma Diamond, CD). Complementarily, heat treatment was performed at 170 °C for 10 minutes for better understanding the behavior of these materials. Evaluation of DC (n=3) was performed by FTIR spectroscopy, the evaluation of Knoop hardness was made on the top and bottom surfaces (n=3), and three point bending test (n=10) and KIC (n=10) were evaluated on a universal testing machine. The results were submitted to analysis of variance (complemented by Tukey test) or Kruskal-Wallis test with 5% significance level. Analysis of DC (%) revealed differences between tested materials, and all bulk-fill resins had higher values than the conventional resin: SF (75.7) > VBF (66.7) = EXP (66.4) = SDR (62.8), which was also similar to FU (60.0); FU, TECBF (56.6), FBFF (56.6) and CD (54.4) showed similar conversion. KHN values showed variations according to the material and the surface: only SF showed a similar KHN (on the top surface) to CD, however it was not possible to read the bottom surface of this latter material; SF, TECBF and FBFF presented different KHN values on the top and bottom surfaces; EXP, FU, SDR and VBF maintained top and bottom similar hardness values. For FS (MPa), the results varied according to the material: EXP (122.54) = SF (101.09) = CD (99.15), the latter two being similar to FU (83.86) and TECBF (82.71), which did not differ from SDR resin (65.18); the latter showed similar behavior to FBFF (60.85) and VBF (59.90). As for KIC (MPa.mm0.5), EXP (3.35) had the highest value, similar to SF (2.42), which in turn was also equal to the conventional composite CD (2.01); CD presented KIC similar to SDR (1.74); SDR = VBF (1.59) = TECBF (1.57); TECBF, FU (1.54) and FBFF (1.37) were similar. Depending on the material, heat treatment increased the values of the parameters, pointing limitations of polymerization reaction of the studied composites. Based on these results, it can be concluded that: bulk fill resins have high DC, higher than the conventional resin studied; the new class of restorative materials is capable of polymerizing in depth and some materials exhibited similar KHN at the top and bottom surfaces of 4 mm depth specimens; FS and KIC varied according to the material, and the EXP composite showed the highest values for both tests.