The use of mineral additions and substitutions in concrete production is highly beneficial to society. When used as substitutes for cement, they provide an alternative destination to polluting waste while contributing to reducing the power consumption and air pollution associated with cement production. This study investigated the influence of different concentrations of additions and curing periods of concrete mixes with water treatment plant sludge ash (CLETA), rice husk ash (CCA) and blast furnace slag (EAF) on total shrinkage and chloride penetration in concrete prepared with high early strength Portland cement. Ten mixes with water/binder ratios of 0.35, 0.50 and 0.65, with wet cure periods of 3 and 7 days were tested. CLETA substitutions for Portland cement ranged from 0% to 30%. Three-component mixes with 20% CLETA and 5% EAF, 20% CLETA and 10% EAF and a four-component mix with 15% CLETA, 5% EAF and 5% CCA were also tested. Shrinkage was measured using a length comparator at 0, 7, 14, 21, 28, 35, 56, 91, 182 and 365 days after removing the sample from the controlled humidity chamber. After 91 days of drying, samples were tested for chloride penetration to check chloride penetration depths in shrinking test samples. Results indicate that even though shrinkage values at 3 days are slightly higher, no significant variation was found for different curing periods. The lowest shrinkage value was found in the reference sample for all tested periods and in the two curing periods. Next, in an increasing shrinkage values, came the following samples: 5%CLETA (5 L), 10% CLETA (10 L), 15% CLETA (15 L), which displayed, for most mixes, a similar behavior to that of 10% CLETA (10 L), followed by mixes 20% CLETA (20 L), 25 %CLETA (20 L) and 30% CLETA (30 L). Chloride penetration resistance increased when the curing time was increased from 3 to 7 days. Three- and four-component mixes showed improved performance when compared to binary samples with CLETA and Portland cement. / O uso de adições minerais e de substituições destas no processo de produção do concreto traz grande benefício à sociedade, por dar um destino a resíduos poluentes e, principalmente, por reduzir o consumo de energia e a poluição do ar gerados pela produção do cimento, ao substituir grande parte desse produto na indústria da construção civil. Neste estudo, investigou-se a influência do teor e do período de cura na utilização de misturas contendo diferentes teores de cinza de lodo de ETA (CLETA), cinza de casca de arroz (CCA) e escória de alto forno (EAF), frente à retração total e à penetração de cloretos de concretos com cimento Portland de alta resistência inicial. Para isso, foram testadas dez misturas aglomerantes, nas relações água/aglomerante 0,35, 0,50 e 0,65, com períodos de cura úmida de 3 e 7 dias. As substituições do cimento Portland por CLETA variaram de 0% a 30%, havendo ainda misturas ternárias, 20% CLETA e 5% EAF, 20% CLETA e 10% EAF, e quaternária, 15% CLETA, 5% EAF e 5% CCA. As leituras de retração foram realizadas com o uso do comparador de expansibilidade nas idades de ensaio, 0, 7, 14, 21, 28, 35, 56, 91, 182 e 365 dias após a retirada da câmara úmida. Após o período de 91 dias de secagem, foi realizado o ensaio de penetração de cloretos por imersão, a fim de analisar a profundidade de penetração de cloretos em corpos de prova em estado de retração. Dos resultados obtidos, constatou-se que, de maneira geral, embora tenham sido observados valores de retração pouco maiores para a cura de 3 dias, não foi constatada variação pronunciada entre os prazos de cura. De todas as misturas investigadas, a que apresentou menor valor de retração foi a de referência, em todas as idades de ensaio e nos dois períodos de cura. Seguido desta, em ordem crescente de retração, vem 5%CLETA (5 L), 10% CLETA (10 L), 15% CLETA (15 L), que tiveram na maioria das misturas um comportamento similar ao de 10% CLETA (10 L), seguido das misturas 20% CLETA (20 L), 25 %CLETA (20 L) e 30% CLETA (30 L). No que diz respeito à penetração de íons cloreto, houve um aumento na resistência quando o tempo de cura passou de 3 para 7 dias. Constatou-se que as misturas ternárias e quaternárias apresentam melhores desempenhos quando comparadas às misturas binárias, compostas por CLETA e cimento Portland.

Direct Write (DW) defines an emerging group of technologies that allow the printing of electronic and other functional components out of vacuum, directly onto conformal surfaces. Both ink-jet and nozzle deposition technologies, which are seen to be complementary for the wide range of materials and processing required by industry, are employed in this project.Silver neodecanoate salt is sensitive to both light source, including ultra violet light (UV) and heat source, and is a good inkjet printing precursor when dissolved in xylene. We have studied the electrical properties of inkjet printed silver samples, derived from silver neodecanoate ink, and investigated the influence of UV treatment before thermal curing the silver samples. UV exposure at room temperature is believed to control the nucleation of silver particles. In addition we have studied the influence of thermal pre-treatment on the printed samples. This pre-treatment is thought to assist the neodecanoate precursor to form a uniform distribution of silver nanoparticles. The influence of UV exposure, thermal pre-treatment and the thermal curing conditions on subsequent track microstructure, and its influence on electrical resistivity is reported for glass substrates. Furthermore, a series of extruding experimental at different nozzle offset and pumping pressure settings are conducted based on the rheological property of silicone oil and silver paste to find the ideal condition for producing continuous tracks with good shape. These findings are used to simulate a computer model for further applications.

The hydration behavior of the calcium aluminates as a function of the glass content, the curing temperature, and the water-solid ratio was investigated. In order to keep them from influencing the results, the free-lime content and the surface area of all samples were kept constant, whenever possible. Samples were hydrated with a water-solid ratio of 10/1 for periods of 1 to 90 days. Three curing temperatures were studied; 2°C, 25°C, and 50°C. Samples were hydrated in tightly sealed polyethylene containers to prevent reactions with atmospheric carbon dioxide. The hydration was followed by X-ray diffraction and thermal analysis. Only two samples, Hexacalcium Tetra-alumino Magnesium Silicate and Tricalcium Magnesium Dialuminate, were successfully prepared in an amorphous form. These compounds were used to investigate the effect of glass content on the hydration behavior. Results indicate that when the glass content is increased a corresponding increase is found in the percent combined water. Samples hydrated at 25°C were influenced by changes in the glass content to a greater degree than were those hydrated at either 2°C or 50°C. The effect of the water-solid ratio on the hydration behavior of the calcium aluminates was studied using the compounds; Hexacalcium Tetra-Alumino Magnesium Silicate/ and Dodecacalcium Hepta-Aluminate. In general, samples that were hydrated with large water-solid ratios reacted more completely than did those hydrated with small water-solid ratios. The presence of sufficient water to theoretically hydrate the samples to completion did not guarantee that the sample would do so. The curing temperature influenced the hydration behavior to a greater degree than did the glass content or the water-solid ratio. Increasing the curing temperature not only increased the rate of hydration, but, in some cases, also changed the hydration products.

The main result of underground mining extraction is creating of large underground voids (mine stopes). These empty openings are typically backfilled with an engineering cementitious material called cemented paste backfill (CPB). The main purpose of CPB application in underground mining is to provide stability and ensure the safety of underground openings, maximize ore recovery, and also provide an environmental-friendly means of underground disposal of potential acid generating tailings. CPB is a mixture of mine tailings, cement binder and water. CPB has a complex geotechnical behaviour when poured into mine voids. This is because of the different thermal (T), hydraulic (H), mechanical (M) and chemical coupled processes and interactions that take place in CPB soon after placement. In addition to these THMC behaviours, various external factors, such as stope geometry, drainage condition and arching effects add more complexity to its behaviour. In order to acquire a full understanding of CPB behaviour, there is a need to consider all of these THMC factors and processes together. So far, there has not been any study that addresses this research need. Indeed, fundamental knowledge of the THMC behaviour of CPB provides a key means for designing safe and cost-effective backfill structures, as well as optimizing mining cycles and productivity of mines. Innovative experimental tools and CPB testing methods have been developed and adopted in this research to fulfill the objectives of this research. In the first phase of the study, experiments with high columns are developed to study the THMC behaviour of CPB from early to advanced ages with respect to height of the column and curing time. The column experiments simulate the mine stope and filling sequence and provide an opportunity to study external factors, such as evaporation, on the THMC behaviour of CPB. However, an important factor is the overburden pressure from the stress due to self-weight that cannot be simulated through column experiments. Therefore, in the second phase of this study, a novel THMC curing under stress apparatus is developed to study the THMC behaviour of CPB under various pressures due to the self-weight of the CPB, drainage conditions, and filling rate and sequence. Comprehensive instrumentation and geotechnical testing are carried out to obtain fundamental knowledge on the THMC behaviour of CPB in different curing conditions from early to advanced ages. The results of these studies show that the THMC properties of CPB are coupled. Important parameters, such as curing stress, self-desiccation due to cement hydration, temperature, pore water chemistry, and mineralogical and chemical properties of the tailings, have significant influence on the shear strength and compressive strength development of CPB. Factors such as evaporation and drying iii shrinkage can also affect the hydro-mechanical properties of CPB. The curing conditions (such as curing stress, drainage and filling rate) also has significant impact on CPB behaviour and performance. The THMC interactions and the degree of influence of each factor should be included in designing backfill structures and planning mining cycles. This innovative curing under stress technique can be replaced the conventional curing of CPB (curing under zero stress and no THMC loadings), in order to optimize CPB mechanical strength assessment, increase mine safety and enhance the productivity.

The diploma thesis deals with the study of hydration of reactive powder concrete under hydrotermal conditions. The theoretical part describes the properties of materials and additives used for the preparation of mixtures. The following describes the principles and requiments for the materials for preparing the reactive powder concrete. The practical part is studied design method mix and the impact of materials to the consistency of paste. The effect of cample placement on flexural and compressive strength of the prepared mixtures was observed. The samples were stored under standart laboratory conditions and under hydrothermal conditions. The phase composition of the samples was monitored by X-ray diffraction analysis and the mocrostructure by scanning electron microscopy.

No description available.

Diplomová práce je zaměřena na přípravu koloidních suspenzí, vytvrditelných UV zářením, jenž jsou určeny k 3D tisku komplexních keramických vláknových struktur. Rovněž jsou v práci představeny techniky následného tvarování vytisknutých a vytvrzených struktur. Z hydroxyapatitu ve formě prášku a komponent, vytvrditelných UV zářením, byly vytvořeny pasty, určené k 3D tisku komplexních keramických vláknových struktur a multivrstev. U takto vytisknutých a vytvrzených struktur bylo navíc dosaženo zlepšení kvality povrchu a soudržnosti vláken. Pro výrobu past, určených k 3D tisku, s vhodnými reologickými vlastnostmi je nezbytné důkladné pochopení interakcí mezi částicemi, surfaktantem a monomerní/oligomerní směsí. Za použití lineárních a zesíťujících oligomerů jako disperzního média vznikají po tisku a UV vytvrzení velmi flexibilní vláknové mřížky, které lze dále tvarovat a takto vytvářet rozmanité struktury. Tyto struktury jsou následně slinuty, bez významných vad na povrchu či delaminace vrstev, za vzniku složitých keramických těles. Vysoké kvality povrchu je dosaženo UV vytvrzením vytisknutých struktur v argonové atmosféře, která brání kyslíkové inhibici radikálů v blízkosti povrchu vláken. Výhody kombinace 3D tisku s UV vytvrzováním jsou demonstrovány v této práci za užití dvouvrstvých flexibilních struktur, určených k následným metodám 3D tvarování. Takto vytvořených složitých 3D struktur je jen velmi obtížné, ne-li nemožné, dosáhnout pouze užitím přímého 3D tisku. Na základě této práce může být v budoucnu odvozena univerzální teorie k přípravě past, určených k 3D tisku komplexních keramických struktur pro různé aplikace.

Reactive powder composites (RPC) have been recently a subject of many researches of modern concrete technology. This type of concrete is very fine and its behaviour exceeds the other types of concrete, therefore there are new possibilities of its use. The design and production of RPC is complex technology process which needs to gain new results in RPC research to get the best features regarding its higher price. This thesis is focused on design of reactive powder concrete (RPC200), which compressive strength is between 200 – 300 MPa. Next goal is to prove the influence of curing regimes like high temperature or pressure, and also check the possibilities of production of low cement reactive powder composite (LCRPC).

I Sverige produceras varje år grovt uppskattat ca. 1,5–2,0 miljoner m2 industrigolv av betong [1]. Resultaten är varierande och det vanligaste felet hos dessa golv är sprickor [2]. I sprickorna letar sig vatten och i vissa fall klorider ned och förorsakar armeringskorrosion. Armeringen expanderar pga. korrosionen och spränger sönder betongen. Golvet blir inte längre estetiskt tilltalande samtidigt som livslängden förkortas avsevärt och golvytan blir ojämn vilket försvårar eventuell trucktrafik. Sprickor uppkommer främst pga. tvångskrafter som uppstår när betongen krymper. Storleken på sprickorna avgörs av betongens benägenhet att krympa, armerings-innehåll och graden av tvång. DynaMate som bygger och underhåller Scanias serviceverkstäder och industrilokaler upplever stora problem med sprickbildning hos industrigolven. Sprickorna medför stora kostnader i form av driftstopp, rivning, reparation och eventuell nyproduktion [3]. Föreliggande rapport baseras framförallt på litteraturstudier utifrån en rad rapporter, artiklar och handböcker men även normer. Intervjuer har genomförts med sakkunniga personer för att ta del av deras erfarenheter och åsikter. För att även få bättre insikt i utförandeskedet har författarna närvarat vid två olika gjutningar av industrigolv. För att minska sprickrisken i betonggolv, orsakad av betongens fria krympning, krävs en betongsammansättning som minimerar den fria krympningen, ett armeringsinnehåll som överstiger minimiarmering, fogar som tillåter rörelser i plattan och en långsam uttorkning. Det har upplevts att problem med sprickor i betonggolv beror på okunskap, olika viljor och slarv bland involverade aktörer. Därför är det även viktigt med tydliga mål och bra kommunikation mellan alla aktörer. På uppdrag av DynaMate har ett förslag till åtgärdsprogram för minskad sprick-bildning tagits fram. Detta kan ligga till grund för framtida golvprojekt och på sikt minska de stora kostnader som underhåll och reparationer medför. / Roughly estimated 1,5–2,0 million m2 of industrial concrete floors are produced in Sweden every year [1]. The results vary and the most common matter/failure among these floors is cracks [2]. Water finds its way down in the cracks and in some cases chlorides, which causes corrosion of the reinforcement. The reinforcement expands due to the corrosion and makes the concrete burst. The floor is no longer esthetically appealing. At the same time the lifetime is shortened substantially and the floor surface becomes uneven which complicates any truck traffic. Cracks arise due to restraint forces that develop because of concrete shrinkage. The width of the cracks is determined by the concretes tendency to shrink, reinforcement content and the extent of restraint forces. DynaMate builds and maintains Scania service centers and industrial facilities. They are experiencing major problems with cracking in industrial floors. The cracks bring large costs in terms of downtime, demolition, repair and any new production. The present report is based mainly on literature research from reports, articles and handbooks but also norms. Interviews were performed with qualified persons to share their experiences and opinions. To receive even more knowledge the authors attended two different castings of industrial floors. A reduction of cracking in concrete floors caused by the free shrinkage requires a concrete composition which minimizes the free shrinkage, reinforcement content in excess of minimum reinforcement, a slow drying and joints that allow movements. It was believed that the problem with cracks in concrete floors is due to ignorance, different wills and carelessness among the involved actors. Consequently it is also important to have clear objectives and good communication between all actors. On behalf of DynaMate a proposal for actions to reduce cracking was prepared. That proposal can form the basis for future flooring projects and ultimately reduce the significant costs due to maintenance and repairs.

Antimicrobial resistance (AMR) is concerning because it limits antimicrobial drug treatment options. AMR occurs by the overuse and misuse of antimicrobial drugs. In environmental settings, AMR can disseminate from places of high use, which leads to increased exposure to humans and animals. A previous study from our laboratory group showed extended-spectrum cephalosporinase-producing Escherichia coli/Klebsiella pneumoniae were isolated from fecal samples obtained in rural Cambodian community settings. Based on these isolates, this study has two aims. The first aim was characterization of selected Cambodian isolates with random amplification polymorphic DNA (RAPD) and antibiotic susceptibility test. From RAPD, the selected six isolates are diverse, except for C61 and C66 bacteria isolates with potential clonality. Additionally, the selected isolates are multidrug resistant (MDR) with reduced susceptibility to beta-lactams and fluoroquinolones. The second aim was to assess two developed methodologies, multiplex automated genome engineering (MAGE) and One-Step Curing Plasmid, by validation in bacteria laboratory strain and development for six Cambodian isolates. To modify AMR genetic elements, MAGE uses pMA7-SacB for homologous recombination with oligos for chromosomal gene disruption. Meanwhile, One-Step Curing Plasmid uses pFREE with the CRISPR/Cas9 system for plasmid and self-curing. Validation showed that MAGE can modify 8% of E. coli MG1655 with lacZ control screening oligos and almost 90% are cured from pFREE. Selected Cambodian isolates have antibiotic-resistance plasmids of IncR or IncFII replicon. For usage in Cambodian isolates, pFREE was modified to be pCAM-FREE by cloning IncR and IncFII plasmid as gRNA1 and gRNA5, respectively. Sequencing results showed pCAM-FREE have gRNA5. In conclusion, our study managed to characterize selected Cambodian isolates as MDR and diverse. In a laboratory strain, MAGE and One-Step Curing Plasmid are functional methods. Furthermore, pCAM-FREE was constructed to target IncFII and in the future, MAGE and pCAM-FREE could be tested in Cambodian isolates.