• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 30
  • 17
  • 4
  • 3
  • 2
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 67
  • 11
  • 10
  • 9
  • 8
  • 7
  • 6
  • 5
  • 5
  • 5
  • 5
  • 5
  • 4
  • 4
  • 4
  • 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.
51

Parläsning i helklass på mellanstadiet : En undervisningsdesign för strukturerad avkodningsträning i RtI-modellens lager 1

Hökenklo, Angelica, Gustafsson, Anna January 2023 (has links)
Läsförmågan hos elever i svenska skolan sjunker och alla elever som kommer till mellanstadiet har inte utvecklat en automatiserad avkodningsförmåga. En begränsad avkodningsförmåga som kvarstår ända upp till mellanstadiet kan leda till svårigheter att inhämta kunskaper i skolans samtliga ämnen eftersom läsningen behövs för attlära genom läsning. Elever på mellanstadiet behöver därför erbjudas strukturerad avkodningsträning, något som inte alltid görs delvis på grund av avsaknad avspecialpedagogiska resurser, träningstid och kompetensbrist. Syftet med föreliggande studie var att undersöka om en undervisningsdesign som erbjuder strukturerad avkodningsträning i RtI-modellens lager 1 på mellanstadiet kan ge positiv effekt på samtliga elevers avkodningsförmåga. Eftersom studier visat att en förbättrad avkodningsförmåga även kan förbättra läsförståelsen mäts även denna förmåga. I studien, som omfattade 16 strukturerade träningspass i par under fyra veckor, ingick 62 elever i interventionsgruppen och 18 elever i jämförelsegruppen. Studien hade en mixed-methods design där effekten av avkodningsträningen i interventionen analyserades kvantitativt och de deltagande lärarnas upplevelser analyserades kvalitativt. Resultaten har visat att undervisningsdesignen Parläsning i helklass på mellanstadiet haft positiv effekt på avkodning och att den är användbar. Studien visade även att undervisningsdesignen kräver pre-test och post-test för att upptäcka och erbjuda elever med misstänkta läs- och skrivsvårigheter insatser enligt RtI-modellens olika lager.
52

Incumbency effects in English Local Elections 1974-2010 : assessing the advantage of electoral defence

Turner, Michael Thomas Eugeniusz January 2014 (has links)
The study of electoral defence and its stated advantages are an integral part of American political science. Post-war, much academic literature has emerged in an attempt to identify and explain rising re-election rates of congressional incumbents and the political consequences of such a phenomenon (Mayhew 1974; Fiorina 1977; Cain, Ferejohn & Fiorina 1987; Gelman & King 1990; King 1991). Conversely, the study of political incumbency in Britain can be attributed to a handful of scholars who tend to consider the repercussions at parliamentary level (Williams 1967, King 1981, Cain, Ferejohn and Fiorina 1984, Norton 1990 & 1994, Norris, Valance & Lovenduski 1992). Consequently, incumbency advantage at the local level remains a relatively under-researched topic in England, confined to the sub-chapters of Rallings & Thrasher (1997). The aim of this thesis is to research and present evidence in support of incumbency effects in English local elections and the extent to which they influence their outcome, in that, incumbent candidates fare better than less experienced candidates, to different degrees across the three major parties. It will do so using survey and electoral data collected by The Elections Centre at Plymouth University, drawing on established methods from the literature and demonstrating via a variety of data and methods, that incumbency advantage is indeed a real phenomenon effecting the outcomes of local elections in England. The research provides substantial evidence for Sophomore Surge and Retirement Slump effects throughout the period examined (1974-2010). These methods of estimation feature alongside a number of others, which are constructed to uncover the significance of defending, rather than challenging for a council seat. A number of influences on the advantage that defending councillors maintain are also presented, including district magnitude, ward size and rural/urban classification. Results reveal a modest advantage for Conservative and Labour incumbent candidates, whilst the effects are shown to be stronger for the Liberal Democrats, a finding that is in step with the existing literature on electoral trends and the local campaign strategy of the party (Dorling et al, 1998; McAllister et al, 2002; Russell & Fieldhouse, 2005; Cutts 2006).
53

Structural Behaviour of Self Consolidating Steel Fiber Reinforced Concrete Beams

Cohen, Michael I. 26 July 2012 (has links)
When subjected to a combination of moment and shear force, a reinforced concrete (RC) beam with either little or no transverse reinforcement can fail in shear before reaching its full flexural strength. This type of failure is sudden in nature and usually disastrous because it does not give sufficient warning prior to collapse. To prevent this type of shear failure, reinforced concrete beams are traditionally reinforced with stirrups. However, the use of stirrups is not always cost effective since it increases labor costs, and can make casting concrete difficult in situations where closely-spaced stirrups are required. The use of steel fiber reinforced concrete (SFRC) could be considered as a potential alternative to the use of traditional shear reinforcement. Concrete is very weak and brittle in tension, SFRC transforms this behaviour and improves the diagonal tension capacity of concrete and thus can result in significant enhancements in shear capacity. However, one of the drawbacks associated with SFRC is that the addition of fibers to a regular concrete mix can cause problems in workability. The use of self-consolidating concrete (SCC) is an innovative solution to this problem and can result in improved workability when fibers are added to the mix. The thesis presents the experimental results from tests on twelve slender self-consolidating fiber reinforced concrete (SCFRC) beams tested under four-point loading. The results demonstrate the combined use of SCC and steel fibers can improve the shear resistance of reinforced concrete beams, enhance crack control and can promote flexural ductility. Despite extensive research, there is a lack of accurate and reliable design guidelines for the use of SFRC in beams. This study presents a rational model which can accurately predict the shear resistance of steel fiber reinforced concrete beams. The thesis also proposes a safe and reliable equation which can be used for the shear design of SFRC beams.
54

Structural Behaviour of Self Consolidating Steel Fiber Reinforced Concrete Beams

Cohen, Michael I. 26 July 2012 (has links)
When subjected to a combination of moment and shear force, a reinforced concrete (RC) beam with either little or no transverse reinforcement can fail in shear before reaching its full flexural strength. This type of failure is sudden in nature and usually disastrous because it does not give sufficient warning prior to collapse. To prevent this type of shear failure, reinforced concrete beams are traditionally reinforced with stirrups. However, the use of stirrups is not always cost effective since it increases labor costs, and can make casting concrete difficult in situations where closely-spaced stirrups are required. The use of steel fiber reinforced concrete (SFRC) could be considered as a potential alternative to the use of traditional shear reinforcement. Concrete is very weak and brittle in tension, SFRC transforms this behaviour and improves the diagonal tension capacity of concrete and thus can result in significant enhancements in shear capacity. However, one of the drawbacks associated with SFRC is that the addition of fibers to a regular concrete mix can cause problems in workability. The use of self-consolidating concrete (SCC) is an innovative solution to this problem and can result in improved workability when fibers are added to the mix. The thesis presents the experimental results from tests on twelve slender self-consolidating fiber reinforced concrete (SCFRC) beams tested under four-point loading. The results demonstrate the combined use of SCC and steel fibers can improve the shear resistance of reinforced concrete beams, enhance crack control and can promote flexural ductility. Despite extensive research, there is a lack of accurate and reliable design guidelines for the use of SFRC in beams. This study presents a rational model which can accurately predict the shear resistance of steel fiber reinforced concrete beams. The thesis also proposes a safe and reliable equation which can be used for the shear design of SFRC beams.
55

I dina händer, O Tärning! : En religionspsykologisk litteraturanalys av protagonisten i George Cockcrofts berättelse om Tärningsspelaren

Clason, Per-Anders January 2010 (has links)
Denna uppsats ämnar, att med bakgrund i den analytiska psykologin, analysera jag-utvecklingen hos Luke Rhinehart, huvudkaraktär i George Cockcrofts berättelse Tärningsspelaren. Uppsatsen redogör för protagonistens psyke med hänvsning till citat ur berättelsen, och diskuterar dessa citat med bakgrund i den analytiska psykologin. Målet är att förstå protagonistens förhållande till tärningen, och däri finna vilka psykiska krafter som är aktiva och som bidrar till den underkastelse berättelsens protagonist företar sig i kombination med tärningen.
56

Att investera i toppen av en högkonjunktur : Ett fenomen i svensk börshistoria / To invest at the top of an economic boom : A phenomenon in the Swedish stock market history

Wennerström, Carl-Ludvig, Bäckdahl, Dennis January 2008 (has links)
Bakgrund: Åren 86-97 kännetecknas som en period med flera stora reformer och en svensk konjunktur som nådde sin botten med tre år i följd av negativ BNP-tillväxt. Påtagligt var även reaktionen från Stockholmsbörsen som i samband med lågkonjunkturen upplevde en kraftig nedgång. Vad drev då denna avkastningsutveckling, vinsterna eller värderingarna av dessa? Hur såg sambandet ut mellan konjunktur, bolagsvinster, vinstvärderingar och börsutveckling för perioden? Syfte: Syftet med denna uppsats, på uppdrag av Melker Schörling AB, är att studera avkastningsutveckling, bolagsvinster och P/E-multiplar över en konjunkturcykel för att analysera till vilken grad multipelexpansion/kontraktion kontra vinsttillväxt drivit avkastningen för olika branscher på Stockholmsbörsen. I ett andra skede utreds huruvida prognoser för P/E-tal och branschvinster på Stockholmsbörsen korrelerat med konjunkturen samt även hur EBITDA- och vinstmarginaler inverkat på aktievärderingar under tidsperioden. Utifrån studiens resultat kommer eventuella lärdomar kopplas till dagens konjunkturella situation. Genomförande: Insamlat datamaterial i form av siffror och nyckeltal utgår från Affärsvärldens tidsskrifter och årsböcker med början 1986 och slut 1997. Utifrån dessa har, för studien, relevanta beräkningar dessutom gjorts. Resultat: Studien av Stockholmsbörsen 86-97, där handelsbranschen genomled konjunkturnedgången bäst, visar inte på att konjunkturen spelar roll för avkastningsutvecklingen. Vinstprognoserna drev avkastningen under lågkonjunkturen medan vinstvärderingarna dämpade nedgången. Genomgående ökade vinstvärderingarna under lågkonjunkturen till följd av att vinstprognoserna föll mer än kursen. Studien visar på att dessa ökade vinstvärderingar innehöll överskattade vinstförväntningar. Innan börsnedgången befann sig P/E-talen på relativt låga nivåer och när utväxlingen i samband med lågkonjunkturens slut skedde var P/E-talen höga, vilket ifrågasätter huruvida P/E-talet egentligen är representativt under en lågkonjunktur samt dess förmåga att indikera på risk. Prognostiserat P/E-tal korrelerar väl med faktiskt P/E-tal men det faktiska fluktuerar i större grad. Marginalerna, som korrelerar negativt med vinstvärderingarna, uppvisar en laggningseffekt gentemot omsättningen. / Background: The years 86-97 are characterized as a period with many big reformations when the Swedish economy reached its bottom with three years in a row with negative GDP. The reaction from the Swedish stock market was substantial and Stockholmsbörsen went through a heavy bearish period. What was it that drove this stock return, the expected earnings or the valuation of them? What was the connection between the business cycle, earnings, valuations and stock return for this particular period? Aim: The aim of the thesis, on behalf of Melker Schörling AB, is to study stock return, company earnings and price-earnings ratios during a business cycle in order to analyse to what extent multiple expansion/contraction versus earnings growth have driven stock return for the different branches on Stockholmsbörsen. In a second stage we observe how estimates of branches’ price-earnings ratios and earnings correlate with the business cycle and what impact EBITDA and pre-tax profit margin have on valuation during the period. Based on the result of the thesis, contingent knowledge will be related to today’s economic situation. Completion: The data, consisting of figures and ratios, is collected from magazines and yearbooks of Affärsvärlden starting 1986 and ending 1997. With the help of these, relevant calculations have been made. Result: This study of Stockholmsbörsen during the years 86-97, where the consumer-goods index had the best performance, shows that the business cycle has no impact on the stock return. The earnings estimates drove the stock return during the economic slump of 91-93 while the valuations tempered the fall. Through the economic slump the valuations became higher due to the fact that the earnings estimates fell more than the stock return. The study also shows that the increased valuations consisted of overestimated earnings estimates. Before the stock market fell the price-earnings ratios were at relatively low levels and when bull period begun in the end of the economic slump the ratios were high. This fact questions whether the price-earnings ratio is representative during an economic slump and if the ratio indicates risk accurately. Forward PE correlates positively with current PE, but the current PE is more volatile. Margins, which correlate negatively with valuations, indicate a lagging effect towards sales growth.
57

Att investera i toppen av en högkonjunktur : Ett fenomen i svensk börshistoria / To invest at the top of an economic boom : A phenomenon in the Swedish stock market history

Wennerström, Carl-Ludvig, Bäckdahl, Dennis January 2008 (has links)
<p>Bakgrund: Åren 86-97 kännetecknas som en period med flera stora reformer och en svensk konjunktur som nådde sin botten med tre år i följd av negativ BNP-tillväxt. Påtagligt var även reaktionen från Stockholmsbörsen som i samband med lågkonjunkturen upplevde en kraftig nedgång. Vad drev då denna avkastningsutveckling, vinsterna eller värderingarna av dessa? Hur såg sambandet ut mellan konjunktur, bolagsvinster, vinstvärderingar och börsutveckling för perioden?</p><p>Syfte: Syftet med denna uppsats, på uppdrag av Melker Schörling AB, är att studera avkastningsutveckling, bolagsvinster och P/E-multiplar över en konjunkturcykel för att analysera till vilken grad multipelexpansion/kontraktion kontra vinsttillväxt drivit avkastningen för olika branscher på Stockholmsbörsen.</p><p>I ett andra skede utreds huruvida prognoser för P/E-tal och branschvinster på Stockholmsbörsen korrelerat med konjunkturen samt även hur EBITDA- och vinstmarginaler inverkat på aktievärderingar under tidsperioden. Utifrån studiens resultat kommer eventuella lärdomar kopplas till dagens konjunkturella situation.</p><p>Genomförande: Insamlat datamaterial i form av siffror och nyckeltal utgår från Affärsvärldens tidsskrifter och årsböcker med början 1986 och slut 1997. Utifrån dessa har, för studien, relevanta beräkningar dessutom gjorts.</p><p>Resultat: Studien av Stockholmsbörsen 86-97, där handelsbranschen genomled konjunkturnedgången bäst, visar inte på att konjunkturen spelar roll för avkastningsutvecklingen. Vinstprognoserna drev avkastningen under lågkonjunkturen medan vinstvärderingarna dämpade nedgången. Genomgående ökade vinstvärderingarna under lågkonjunkturen till följd av att vinstprognoserna föll mer än kursen. Studien visar på att dessa ökade vinstvärderingar innehöll överskattade vinstförväntningar. Innan börsnedgången befann sig P/E-talen på relativt låga nivåer och när utväxlingen i samband med lågkonjunkturens slut skedde var P/E-talen höga, vilket ifrågasätter huruvida P/E-talet egentligen är representativt under en lågkonjunktur samt dess förmåga att indikera på risk. Prognostiserat P/E-tal korrelerar väl med faktiskt P/E-tal men det faktiska fluktuerar i större grad. Marginalerna, som korrelerar negativt med vinstvärderingarna, uppvisar en laggningseffekt gentemot omsättningen.</p> / <p>Background: The years 86-97 are characterized as a period with many big reformations when the Swedish economy reached its bottom with three years in a row with negative GDP. The reaction from the Swedish stock market was substantial and Stockholmsbörsen went through a heavy bearish period. What was it that drove this stock return, the expected earnings or the valuation of them? What was the connection between the business cycle, earnings, valuations and stock return for this particular period?</p><p>Aim: The aim of the thesis, on behalf of Melker Schörling AB, is to study stock return, company earnings and price-earnings ratios during a business cycle in order to analyse to what extent multiple expansion/contraction versus earnings growth have driven stock return for the different branches on Stockholmsbörsen.</p><p>In a second stage we observe how estimates of branches’ price-earnings ratios and earnings correlate with the business cycle and what impact EBITDA and pre-tax profit margin have on valuation during the period. Based on the result of the thesis, contingent knowledge will be related to today’s economic situation.</p><p>Completion: The data, consisting of figures and ratios, is collected from magazines and yearbooks of Affärsvärlden starting 1986 and ending 1997. With the help of these, relevant calculations have been made.</p><p>Result: This study of Stockholmsbörsen during the years 86-97, where the consumer-goods index had the best performance, shows that the business cycle has no impact on the stock return. The earnings estimates drove the stock return during the economic slump of 91-93 while the valuations tempered the fall. Through the economic slump the valuations became higher due to the fact that the earnings estimates fell more than the stock return. The study also shows that the increased valuations consisted of overestimated earnings estimates. Before the stock market fell the price-earnings ratios were at relatively low levels and when bull period begun in the end of the economic slump the ratios were high. This fact questions whether the price-earnings ratio is representative during an economic slump and if the ratio indicates risk accurately. Forward PE correlates positively with current PE, but the current PE is more volatile. Margins, which correlate negatively with valuations, indicate a lagging effect towards sales growth.</p>
58

Analyse de l'effet d'un adjuvant biosourcé pour élaborer des matériaux cimentaires plus éco-respectueux / Study of environmental friendly concrete : use of bacterial products to improve their durability

He, Huan 17 July 2015 (has links)
Cette thèse s’inscrit dans le cadre du projet SEPOLBE qui a pour ambition d’élaborer des adjuvants respectueux de l’environnement qui doivent se substituer à des produits soumis à autorisation REACH. Elle a pour but de mettre en évidence les propriétés de mortiers enrichis d’un adjuvant fabriqué à partir de produits extracellulaires issus de bactéries selon un protocole original. Ce travail consiste en l’étude des caractéristiques de mortiers bioadjuvantés dans le but de développer l’usage de bétons plus éco‐respectueux en améliorant leurs compositions chimiques et leur durabilité. L’action du produit biologique utilisé a été évaluée aussi bien sur sa capacité à modifier le réseau poreux des mortiers et pâtes cimentaires que sur ses effets sur la prise du ciment, la rhéologie à l’état frais et les caractéristiques mécaniques à l’état durci des mortiers permettant ainsi de qualifier ce produit comme bioadjuvant. Il a présenté un effet notable sur l’ouvrabilité de mortiers (de CEM I ou CEM V) avec une action plastifiante. De plus, quel que soit le temps de cure, un optimum de concentration en bioadjuvant de 1,5% a été déterminé pour obtenir des résistances mécaniques dumême ordre de grandeur que les échantillons non adjuvantés, et supérieures au minimum requis par la norme EN 196‐1. Le bioadjuvant n’influence pas la porosité totale accessible à l’eau des mortiers et des pâtes de ciment, toutefois, pour ces dernières, les mesures par porosimétrie par injection de mercure ont révélé l’existence d’un seuil (entre 0,5 et 0,75% de bioadjuvant) à partir duquel la structure poreuse des pâtes cimentaires est modifiée. Les effets de modification de surface de pâtes cimentaires – le liant du béton pouvant constituer un maillon faible en ce qui concerne les problèmes de durabilité de celui‐ci – ont été analysés. Pour des temps de cure élevés, la rugosité des surfaces des pâtes cimentaires diminue en présence du bioadjuvant. Ce travail a permis de lever des verrous techniques concernant l’emploi d’un produit biosourcé en tant qu’adjuvant, ainsi que d’apporter une contribution à la connaissance des interactions entre les micro‐organismes et les matériaux cimentaires. En effet, une approche originale, grâce à la PCR – technique peu utilisée avec les matériaux cimentaires – a permis de mettre en évidence qu’il y avait des bactéries au coeur du béton ayant une capacité à se développer dans des conditions de cures normalisés pour des temps de cure supérieurs à 120 jours. Le bioadjuvant est susceptible de modifier le développement bactérien et présente ainsi la possibilité de conférer aux bétons des capacités de résistances aux agressions environnementales plus importantes lui permettant d’être plus éco‐respectueux, aussi bien par sa composition que par sa meilleure durabilité. / This work is a part of the SEPOLBE project, which aims to develop eco‐friendly admixtures. The active principle of this admixture is made of extra‐cellular substances, secreted by microorganisms into their surroundings. It contributes to the effort in sustainable development that consists to limit the impact of buildings on environment and human health, with a guarantee of better quality concerning esthetical, durability and resistance criteria, according to the REACH regulation. The action of thisorganic product was evaluated on its setting time effects on cement as well as the mechanical behavior to the hardened state. The bioadmixture presents a significant effect on the workability of mortar (CEM I or CEM V) with a plasticizing action. Whatever the curing time, the compressive strength values of samples containing 1.5% of bioadmixture remain higher than the minimum data of standard strength according to the EN 196‐1 standard. The porosimetry by intrusion with mercury carried out with cement pastes showed the existence of a threshold (in the range 0.5‐0.75% of bioadmixture) from which the porous structure of cement pastes changes, while no modification were observed with the measurement of porosity accessible to water. For higher curing times, thesurface roughness of cement pastes, more heterogeneous, decreases with the presence of the bioadmixture. This work allowed to better control the use of a bio‐product assimilated as an admixture, as well as to contribute to the knowledge of the interactions between microorganisms and cementitious materials. An original approach, using the PCR ‐ not routinely used technique forthat purpose with cementitious materials ‐ helped to highlight that bacteria were present inside the mortar samples with a capacity to grow to higher curing time. The studied bioadmixture allows giving to the concrete the ability to resist against environmental stresses while being eco‐friendly, concerning both its chemical composition and its durability.
59

Structural Behaviour of Self Consolidating Steel Fiber Reinforced Concrete Beams

Cohen, Michael I. January 2012 (has links)
When subjected to a combination of moment and shear force, a reinforced concrete (RC) beam with either little or no transverse reinforcement can fail in shear before reaching its full flexural strength. This type of failure is sudden in nature and usually disastrous because it does not give sufficient warning prior to collapse. To prevent this type of shear failure, reinforced concrete beams are traditionally reinforced with stirrups. However, the use of stirrups is not always cost effective since it increases labor costs, and can make casting concrete difficult in situations where closely-spaced stirrups are required. The use of steel fiber reinforced concrete (SFRC) could be considered as a potential alternative to the use of traditional shear reinforcement. Concrete is very weak and brittle in tension, SFRC transforms this behaviour and improves the diagonal tension capacity of concrete and thus can result in significant enhancements in shear capacity. However, one of the drawbacks associated with SFRC is that the addition of fibers to a regular concrete mix can cause problems in workability. The use of self-consolidating concrete (SCC) is an innovative solution to this problem and can result in improved workability when fibers are added to the mix. The thesis presents the experimental results from tests on twelve slender self-consolidating fiber reinforced concrete (SCFRC) beams tested under four-point loading. The results demonstrate the combined use of SCC and steel fibers can improve the shear resistance of reinforced concrete beams, enhance crack control and can promote flexural ductility. Despite extensive research, there is a lack of accurate and reliable design guidelines for the use of SFRC in beams. This study presents a rational model which can accurately predict the shear resistance of steel fiber reinforced concrete beams. The thesis also proposes a safe and reliable equation which can be used for the shear design of SFRC beams.
60

Propuesta de uso de cenizas de cáscara de arroz y fibras de polipropileno en diseños de mezclas de concreto para el control de fisuras en losas macizas entrepiso in-situ en la ciudad de Lima / Proposal for the use of rice husk ash and polypropylene fibers in concrete mix designs for the control of cracking in concrete structures in the city of Lima

Cano Duplex, Bryan Alexander, Galarza Mateo, Edwin Jean Marco 30 November 2020 (has links)
La presente investigación fue elaborada con el fin de estudiar la influencia que tiene el agregar cenizas de cascara de arroz (CCA) y fibras de polipropileno (FPP) en la fisuración por contracción plástica del concreto. El estudio de investigación tuvo lugar en la ciudad de Lima, donde nos enfocamos a investigar las propiedades plásticas y mecánicas de un concreto f´c=210 kg/cm2, que se utiliza comúnmente en la fabricación de losas macizas, con reemplazo parcial del cemento por CCA en porcentajes de 5%, 10% y 15% respecto a su peso, y FPP en rendimiento de 900 gr/m3. Las principales propiedades en estado endurecido fueron investigadas, la resistencia a la compresión y la resistencia a la flexión y la propiedad en estado plástico que se desarrolló fue la fisuración debido a la contracción plástica a través del ensayo ASTM C1579. Teniendo en cuenta que no existe un acuerdo relativo al ancho de fisura máxima en un elemento estructural, se decidió utilizar límites entre 0.2 a 0.4 mm, para ambientes normales, sugeridos por el Mg. Ing. Gianfranco Ottazzi. De los resultados obtenidos, la mezcla adicionada con CCA en reemplazo parcial del cemento en 5%, 10% y 15% junto con las FPP en rendimiento de 900 gr/m3, podemos inferir que las CCA reducirán, no de manera significativa, las propiedades de la resistencia de un concreto f´c= 210 kg/cm2, sin embargo, reducen el promedio de apariciones de fisuras producidas en las losas macizas debido la contracción plástica del mismo. / The present investigation was elaborated with the purpose of studying the influence of the addition of rice husk ash (RHA) and polypropylene fibers (PPF) on the plastic shrinkage cracking of concrete. The research study took place in the city of Lima, where we focused on investigating the plastic and mechanical properties of a concrete f´c = 210 kg / cm2, which is commonly used in the manufacture of solid slabs, with partial replacement of the cement by RHA in percentages of 5%, 10% and 15% respect to its weight and PPF in yield of 900 g / m3. The main properties in the hardened state were investigated, the compressive strength and flexural strength and the property in the plastic state that developed was cracking due to plastic shrinkage through the ASTM C1579 test. Taking into account that there is no agreement regarding the maximum width in a structural element, it was decided to use limits between 0.2 to 0.4 mm, for normal environments, suggested by Mg. Eng. Gianfranco Ottazzi. According to the results obtained, the mixture added with RHA in replacement of cement in percentages of 5%, 10% and 15% together with PPF in yield of 900 gr / m3, we can infer that the RHA will reduce, not significantly, the strength properties of a concrete f´c = 210 kg / cm2, however, reduce the average occurrence of cracks produced in solid slabs due to the plastic shrinkage of the same. / Tesis

Page generated in 0.0314 seconds