This thesis deals with refractory concrete binding system based on aluminous cement and phosphoric acid. The prepared refractory concretes were fired at 1 000 °C. Various effects on compressive strength of refractory concrete were studied. The influence of aluminous cement content and phosphoric acid content, the influence of various admixtures, the influence of plasticizers and the influence of time and method of sample storage were studied. Simultaneous thermogravimetry and differential thermal analysis of the basic unfired sample were performed. Finally, selected refractory concretes were fired at 110, 200, 400, 600, 800, 900, 1 000 and 1 100 °C. The compressive strength of these samples was measured and powder X ray diffraction analysis was performed. The compressive strength of refractory concretes under intermediate temperatures (800–1 100 °C) was most increased in samples with metakaolin and gray microsilica.

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.

The diploma thesis is focused on study of diagnostic methods used for reinforced concrete structure with a practical example of a survey on the subject of the original memorial Bata in Zlin, today's House of Art. The theoretical part of the thesis describes the general methodology of the survey with the distribution methods for testing materials and structures, and displays the evaluation according to ČSN ISO 1382 Also deals with the required properties and used by diagnostic methods for concrete and steel. In the practical part of the surveyed, which is supposed to show the methodology of the survey to the evaluation process involving the setting apart of strength and classification of concrete and chemical analysis, which should show whether the concrete is not based on aluminous cement.

Man vill förkorta betongs bindetid dvs. den tid då betongytan kan behandlas så att betongytan blir slät efter gjutning. Det är en stor utmaning för företag som tillverkar fabriksbetong vintertid, eftersom bindetiden förlängs ju kallare klimatet är. Syftet med denna labboration var att visa hur Kalciumnitrart fungerar som bindetidsaccelerator i betong, och om Kalciumnitrart påverkar betongens fysikaliska egenskaper.  Följande faktorer har studerats för att se hur dessa faktorer påverkar betongens bindetid i kombination med användning av Kalciumnitrat. Betongens utgångstemperartur Typ av flyttillsatsmedel i betongen Betongens utgångskonsistens Betongens lagringsklimat Även hitta rätt dosering för att denna produkt ska vara lönsamt att användas i praktiken. Alla underökningar har utförts hos Sika AB laboratorium. All data har noggrant undersökts och använts i Excel program för framtagning av tabeller och diagram. Resultaten/slutsats i underökningarna visade följande. Bindetiden kan förkortas med Kalciumnitrat utan att behöva riskera betongens fysikaliska egenskaper. Enligt bindetidsdiagram noterades att 2,0 % och 2,5 % doseringarna gav bästa resultat gällande bindetid dvs. de gav kortast bindetid. Observera att +5 graders lagringsklimat gav ologiska resultat dvs. referensbetongen utan acceleratorn gav kortast bindetid. Tryckhållfastheten påverkas inte av acceleratorn dvs. man kan använda denna produkt utan att riskera betongens bärförmåga. Resultaten visade att betongens utgångskonsistens har stor betydelse för bindetiden, ju högre konsistens värde desto längre bindetid. Även betongens utgångstemperatur har påverkan på bindetiden, ju högre betongtemperatur desto kortare bindetid. / You want to reduce the concrete’s initial setting i.e.  the time the concrete surface can be treated so that surface gets plane after molding. It’s a big challenge for the companies that produce mill concrete in winter. Since the colder the climate gets the binding process will be extended. The purpose of this lab was to show how Calcium Nitrate functions as bonding time accelerator in concrete and if Calcium Nitrate affects the physical features of the concrete. The following elements have been studied to see how these elements affect the initial setting of the concrete in combination with the use of Calcium Nitrate. The initial temperature of the concrete The type of super plasticizer in the concrete The initial consistency Concrete storage climate Even finding the right dose so that this product will be profitable to use in the practice. All investigations have been made at Sika AB laboratory. All the data have been investigated and used in excel program for the product of chart and diagram. The results of the investigations showed the following:   Bond time can be reduced with Calcium Nitrate without needing to risk the physical features of the concrete.  According to bonding time diagram it was noted that 2.0 % and 2.5% doses gave the best result valid the initial setting i.e. that gave the shortest time of initial setting, Observe that +5 degrees storage climate gave illogical results i.e. reference concrete without the accelerator gave the shortest initial setting. Compressive strength does not get affected by the accelerator i.e. you can use this product without risking the concretes carrying capacity.  The results showed that the concrete initial consistency has a big importance to bond time, the higher consistency value the longer time of initial setting. Even concrete initial temperature has influence on the bond time, the higher concrete temperature, the shorter time of initial setting.

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.

Heavy-metal contamination in soils has become a serious environmental problem. Among all metals, excessive amount of zinc was released to soils over the years. Zinc is not only toxic to human being, but also to plants. High concentration of zinc is extremely phytotoxic. Currently, the most popular method to remediate heavy-metal contaminated soils is stabilization/solidification (S/S) technique as it is cheaper, faster and more effective to remediate heavy metals than other remediation methods. Portland cement is the most-used binder in S/S technique. However, the production of Portland cement has released a significant amount of carbon dioxide, which strongly contributes to global warming. In addition, zinc retards the setting and hydration of Portland cement, which would require more Portland cement to remediate zinc-contaminated sites. Therefore, researchers are looking for new materials to improve the performance of Portland cement in zinc-contaminated soils. In recent years, the application of graphene-based materials in concrete had proved to be effective. Due to relative cost-effectiveness and comparable properties, multi-layer graphene, known as graphene nanoplatelets, may show a promising potential in construction. Moreover, research has reported that graphene nanoplatelets can be exfoliated from graphite and potentially scaled up for full-scale applications. At present, there is no application of graphene nanoplatelets in the S/S of contaminated soils and the roles of graphene nanoplatelets in cement-stabilized zinc-contaminated clay remained unknown. In this research, graphene nanoplatelets were dispersed in solution with a high-shear mixing apparatus. Dispersed graphene nanoplatelets solution was then applied to zinc-contaminated soil along with cement. To evaluate the efficacy of this S/S method, various influencing factors such as mixing sequence, graphene nanoplatelets content, zinc content, cement content, and curing time were studied. An optimum graphene nanoplatelets content was determined through the unconfined compressive strength (UCS) of the stabilized/solidified samples. It was found that at the optimum content, the unconfined compressive strength of cement-stabilized zinc-contaminated clay was improved by 22.3% with the addition of graphene nanoplatelets. Also, graphene nanoplatelets were effective at moderate zinc content and low cement content. Graphene nanoplatelets accelerated cement hydration effectively at early ages. Microstructural analyses indicated that more hydration products were developed in samples with graphene nanoplatelets. At current stage, it is still expensive to apply graphene nanoplatelets in S/S technique; however, it is possible to exfoliate graphite into graphene nanoplatelets in future research. / Graduate / 2022-05-12

El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado. / This study uses analytical solutions to assess a hydraulic fill model based on weathered granitoid to increase underground opening stability and mitigate rock bursts during mining operations in a conventional underground mining company located in the Coastal Batholiths of the Peruvian Andes. This study assesses the previous geological database provided by the mine, analyzes the on-site strengths produced by the exploitation works that will subsequently be filled, identifies the quality of the material used in the landfill (granitoids) through laboratory tests, and compares compressive strength at different depths, all contemplated within the landfill model used. This study focuses on the applicability of hydraulic fills in conventional underground mine using natural geological material such as granitoid. / Revisión por pares

This thesis presents the results of an investigation of factors which influence the geotechnical properties of frozen mine backfill (FMB). FMB has extensive application potential for mining in permafrost areas. The uniaxial compressive strength (UCS) of hardened backfill is often used to evaluate mine backfill stability. However, the deformation behaviour and stiffness of the FMB are also key design properties of interest. In this thesis, uniaxial compressive tests were conducted on FTB and FCPB samples. Information about the geotechnical properties of FMB is obtained. The effects of FMB mix components and vertical compression pressure on the geotechnical properties of FMB are discussed and summarized. An optimum total water content of 25%-35% is found in which the strength and the modulus of elasticity of the FTB are 1.4-3.2 MPa and 35-58 MPa, respectively. It is observed that a small amount (3-6%) of cement can significantly change the geotechnical properties of FTB.

Cross-Laminated Timber (CLT) has recently become a popular construction material for building timber structures. One advantage of CLT is, that it can be used as floor, beam and wall element. As the arrangements of layers in CLT is in perpendicular direction to each other, it exhibits remarkable strength properties in both in-plane directions. However, the low stiffness and strength properties in compression perpendicular to the grain hinder application of CLT in high rising building, since forces are usually transferred from the wall elements through floor elements perpendicular to the grain. Thus, the aim of this thesis is to get a thorough understanding of the mechanical properties of such connections for different setups, including wood-wood connections, connections with acoustic layers and connections with screws. In addition, the wall was place at different positions on the CLT-floor element. Mechanical tests and numerical simulations, by means of finite element modelling (FEM) were carried out. CLT floor elements, consisting of 5-layers, were loaded by 3-layered CLT wall elements. Displacement and deformation were continuously measured by Potentiometers/LVDTs and an optical measurement system, respectively. Based on the experimental results compressive strength, slip curve and stiffness of the CLT connections were evaluated. Subsequently, results from FE-modelling were compared with experimental findings, which show a good agreement in elastic stiffness. Experimental results exhibited a pronounced influence of the wall position and connection setup on strength and stiffness. Central position of the wall showed higher mechanical properties than edge position. Highest strength and stiffness were found for screwed connections, where the wood-wood connections showed similar results. Connections with acoustic layers exhibited the lowest mechanical properties.

There are approximately 4000 railway bridges in Sweden managed by the Swedish Administration of Transport (Trafikverket), of which a common construction type is the reinforced concrete (RC) trough bridge, which is a structure that consists of a slab carried by two longitudinal main beams which transfer loads towards the supports. A substantial amount of the RC trough bridge population is approaching the end of their service lives which consequently implies that the replacement of some of these bridges can be expected in the near future. Extending their service lives can yield positive effects from a financial- as well as an environmental perspective, and therefore it is highly beneficial to evaluate their capacities as realistically as possible. One factor that may help improve accuracy during the determination of their capacities is an evaluation of how it is affected by the location of the railway track on the bridge.  In current design codes defined by Trafikverket, consideration is taken to horizontal track displacement for a minimum displacement of 0.1 m if there doesn’t exist data suggesting that a larger displacement is prevalent on the bridge. However, Trafikverket has received data which suggest that a considerable number of bridges could experience load eccentricities which exceed the standard minimum value. This raises the question whether or not 0.1m is the most optimal limit value for load eccentricity on railway bridges. For RC trough bridges, a larger load eccentricity may result in one main beam carrying a larger portion of the load which will decrease the axle load which the bridge can carry. It is therefore important to evaluate the influence of larger horizontal displacements than what is currently is considered as a preventive action.   In addition, several studies on Swedish concrete bridges constructed during the 20th century have pointed to a significant increase in concrete compressive- and tensile strength over time. This suggests that it is possible that a considerable amount of RC trough bridges have a higher capacity than what was originally intended, and further research is required in order to understand the behaviour of these bridges when key material parameters are altered.        There are three main tasks which this master thesis seeks to complete. The first part is a detailed analysis of a database named BaTMan (Bridge and Tunnel Management) that belongs to Trafikverket. In this analysis parameters such as span length, age, material type and damages for every identified railway bridge is extracted and further processed in Microsoft Excel in order to gain a clear overview of the RC trough bridge population. The second task regards the development of a non-linear finite element model of a typical RC trough bridge named Lautajokki. The model is analysed using ATENA Science and its behaviour is verified against test results obtained during a full-scale test of the bridge performed by Paulsson et al. (1996). The last task is to use the devolved model to perform a parametric study where the effects of changes in load eccentricity, compressive strength as well as tensile strength is studied.