<p>Concrete is in everyday life such as parking lots, buildings, bridges, and more. To keep concrete and its constituents together, binders such as cement are used. Cement’s production process is responsible for 8% of global carbon dioxide emissions as of 2018. With global warming being a severe global issue, the challenge of reducing cement carbon dioxide emissions can be greatly beneficial with even slight improvements. Various solutions to this challenge have developed over the years in the form of processing efficiency, material substitution, or material additives. Of the additives for cement and concrete that have been ventured, nanomaterials have had a strong development in recent years. Specifically, cellulose nanomaterials in the form of nanocrystals, nanofibrils, and more have demonstrated great improvement in cement’s performance resulting in a reduction in cement produced and reduction in emissions. This study expands on the knowledge of cellulose nanocrystals as an additive for cement using the formation factor methodology. Formation factor is a resistivity ratio of the specimen and pore solution that can be used in correlation to the diffusion of chloride ions through the use of the Nernst-Einstein equation. This study also investigates the effect that cellulose nanomaterials have on the mechanical properties and thermogravimetric analysis of gypsum, a material commonly used in cement production that delays the hardening of cement. </p>

Esta investigación analiza, mediante un estudio experimental, los efectos en las propiedades mecánicas y reológicas del concreto estructural con incorporación de caucho y microsílice (CCM). Se elaboraron 10 diseños de mezcla de CCM con una relación a/c de 0.50 y 340 kg cemento tipo I, reemplazos parciales de caucho de 0, 5, 10, 15 y 20% y microsílice de 0 y 2%, de arena y cemento respectivamente. Además, se incluyó un aditivo superplastificante MasterEase 3900 y un retardante MasterSet R800. La piedra empleada posee un TMN de 3/4" y cumple con la granulometría para Huso 67, la arena y el caucho granulado tienen módulos de fineza de 2.9 y 4.6 respectivamente. La propiedad de resistencia a la compresión fue tomada a los 1, 7 y 28 días de curado; y tracción a los 14 y 28 días de curado. Los resultados de la reología indicaron que las mezclas que contenían 20% de reemplazo de arena por caucho presentaron incompatibilidad con los aditivos lo que conllevo a una falta de consistencia en dichos diseños, con respecto a los demás diseños con reemplazo de caucho de hasta 15%, estos presentaron una mejor conservación de su asentamiento en el tiempo, una disminución en su peso unitario hasta en 8.4%, un aumento en el calor de hidratación inicial lo que conllevo a la obtención de mayores temperaturas del concreto y por último se observó un aumento en el contenido de aire hasta en 1.7%. Al incorporar microsílice en los diseños con caucho se observó que el asentamiento no presentó variaciones significativas, el peso unitario disminuyó en 1.9%, la temperatura del concreto aumentó y se obtuvieron mayores contenidos de aire hasta en 2.5%. Los resultados de las propiedades mecánicas indican que, a mayor contenido de caucho, disminuye la resistencia a la tracción hasta en 35.0% y a la compresión hasta en 43.3%; sin embargo, al adicionar microsílice a los diseños con caucho, la resistencia a la compresión aumentó hasta en un 9.8% y la resistencia a la tracción disminuyó hasta en un 14.8%. / This research analyzes, through an experimental study, the effects on the mechanical and rheological properties of structural concrete with incorporation of rubber and microsilica (CRM). In this investigation, 10 CCM mixture designs were developed with a w / c ratio of 0.50 and 340 kg of type I cement, partial replacements of rubber of 0, 5, 10, 15 and 20% and microsilica of 0 and 2%, of sand and cement respectively. In addition, a MasterEase 3900 superplasticizer additive and a MasterSet R800 retarder were included. The stone used has a maximum size of 3/4” and complies with the granulometry for Huso 67, sand and granulated rubber have fineness modulus of 2.9 and 4.58 respectively. The property of compressive strength was taken at 1, 7 and 28 days of curing; and tensile strength at 14 and 28 days of curing. The rheology results indicated that the mixtures containing 20% replacement of sand by rubber presented incompatibility with the additives, which led to a lack of consistency in these designs, with respect to the other designs with rubber replacement of up to 15%, these presented a better conservation of their slump over time, a decrease in their unit weight of up to 8.4%, an increase in the initial heat of hydration, which led to higher concrete temperatures and, finally, an increase of up to 1.7% in air content was observed. By incorporating microsilica in rubber designs, it was observed that the slump did not present significant variations, the unit weight decreased of up to 1.9%, the temperature of the concrete increased, and higher air of up to 2.5% contents were obtained. The results of the mechanical properties indicate that, the increase of the rubber content, the decrease of the tensile strength up to 35.0% and compressive strength up to 43.4%; however, when adding microsilica the compressive strength increased up to 9.8% and the tensile strength decreased up to 14.8%. / Trabajo de investigación

En este artículo se analiza la influencia de un aditivo a base de nanosilice en el concreto elaborado con agregado a partir de concreto reciclado. Para lo cual, se ha realizado un programa de laboratorio donde se analizan las propiedades físicas de los materiales y las propiedades en estado fresco y endurecido del concreto a distintas edades. El objetivo principal del estudio es demostrar las mejoras cuantitativas de resistencia a compresión y tracción del concreto con ACR empleando nanosilice. Asimismo, el diseño óptimo para los casos propuestos es la mezcla M4 (100% ACR y 1% nanosilice) con el cual se logra mejorar en 21% respecto a la muestra M3 (100% ACR) a 28 días. Finalmente, el diseño M4 tiene una mayor resistencia a compresión comparado con la mezcla M0 (1) concreto convencional sin nanosilice. Por consiguiente, la utilización del concreto con ACR es factible en términos de resistencia. / This article discusses the influence of a nanosilize based admixture on concrete made with aggregate from recycled concrete. For which, a laboratory program has been carried out where the physical properties of the materials and the properties in the fresh and hardened state of concrete at different ages are analyzed. The main objective of the study is to demonstrate the quantitative improvements of resistance to compression and tension of concrete with ACR using nanosilice. Likewise, the optimal design for the proposed cases is the M4 mixture (100% ACR and 1% nanosilize) with which it is possible to improve by 21% compared to the M3 sample (100% ACR) at 28 days. Finally, the M4 design has a higher compressive strength compared to the conventional concrete mix M0 (1) without nanosilize. Therefore, the use of concrete with ACR is feasible in terms of strength. / Tesis

Tillverkning av portlandklinker står för ungefär fem procent av världens totala koldioxidutsläpp. Det finns därför ett allmänt intresse att minska användandet av portlandklinker. Klinkern kan antingen ersättas av andra cementerande material, eller så kan nya cementsnåla recept utformas. I den här rapporten har två cement med inmald flygaska respektive slagg från Cementa AB undersökts. För att undersöka klinkerersättnings-materialens potential har tester för tryckhållfasthet, uttorkningskrympning, bindetid, värmeutveckling och arbetbarhet utförts. Resultaten visar att skillnaderna mellan försökscementen och byggcementet är så pass små att båda bör kunna användas som byggcement. Ytterligare har ultrafiller av kalksten använts som ersättare för att minska cementhalten i betongen. Det går lika bra att delvis ersätta försökscementen med ultrafiller som det gör för byggcementet. Med cementsnåla recept och större del ersättningsmaterial finns det stora möjligheter att spara på energi och miljö. Detta borde i framtiden kunna leda till ett bättre och mer miljövänligt byggmaterial. / Manufacture of clinker is responsible for about five percent of the total global carbon dioxide emissions. Therefore, there is a general interest in reducing the use of clinker. Clinker can either be replaced by other cementitious materials, or reduced by using lean-cement recipes. This report examines two experimental cements, one with fly ash and one with slag, developed by Cementa AB. To examine the potential of clinker replacement materials, tests for compressive strength, drying shrinkage, initial setting, heat generation and workability, were performed. The results show that the differences between the experimental cements and the reference are so small that both are useable as building cements. In addition, an ultrafine filler of limestone is used as a replacement material for further reduction of the clinker content in concrete. It was also found, that it is just as efficient to partly replace the experimental cements with ultrafine filler as in the reference cement. There are great opportunities to save energy and the environment impact with both clinker-saving cement recipes and with cement replacement materials. This should lead to a better, more environmentally friendly, building material in the future.

El Relleno Fluido o también conocido como Material Controlado de Baja Resistencia (CLSM por sus siglas en inglés) vienen siendo requeridos sobre todo en épocas de pandemia por el COVID-19 en lugar del relleno compactado, debido a su gran facilidad y rapidez para los rellenos de cavidades de zanjas, tanto en redes de agua, desagüe y alcantarillado, relleno de cimentaciones de edificios y puentes, entre las principales aplicaciones. El presente estudio contempla el desarrollo de mezclas con contenidos de cemento Portland tipo I de 60 a 90 kg/m3 para rangos de resistencia a compresión entre 5 a 15 kg/cm2 a 28 días, con agregados de la cantera Tinguiña de Ica, y aditivo agente espumante para conferir la fluidez y trabajabilidad necesaria que facilite su colocación en obra. Resultados satisfactorios de fluidez entre 9 ½” a 10 ½” y pérdida de fluidez promedio de 2”/ hora, y rangos de resistencia de hasta 24 kg/cm2 fueron obtenidos, los cuales permitieron un buen comportamiento costo beneficio tanto en ahorro económico, y tiempo de ejecución propuesto para un proyecto real de saneamiento en la ciudad de Ica. Asimismo, gracias a la aplicación de las mezclas de Relleno Fluido propuestas, se preservará el distanciamiento social durante su empleo en obra, dado que solo requiere de una persona para su aplicación en los rellenos de zanjas. / Flowable Fill or also known as Controlled Low Resistance Material (CLSM) have been required especially in times of pandemic by COVID-19 instead of traditional compacted fill, due to its great ease and speed for fillings works of trench cavities, both in water and wastewater networks, filling for foundations in buildings and bridges, among the main applications. The present study contemplates the development of mixtures with Portland cement type I from 60 to 90 kg / m3 for 28 days compressive strength ranges between 5 to 15 kg / cm2, coarse and fine aggregates from the Tinguiña quarry, in Ica city, and foaming agent chemical admixture to provide the adequate fluidity and workability to cast in place at the job site. Satisfactory fluidity results between 9 ½ ” to 10 ½” and average fluidity loss ratio of 2 ”/ hour, and compressive strength ranges of until 24 kg/cm2 were obtained, which a good cost-benefit performance both in economic savings, and execution time for a proposed sanitation project in the city of Ica. Likewise, thanks to the application of the proposed flowable fill mixtures, social distancing will be preserved during its use on site, because it only requires one person to apply it in the trench fillings. / Tesis

The work deals with the preparation and mechanical properties of coated Bioglass® 45S5 based foam materials with open porosity. The samples have been fabricated applying the replication method with use of polyurethane foam. Furthermore, these samples were coated in order to increase the strength characteristics and crack resistance. Polyvinylalcohol and PVA with cellulose microfibrils have been used as coating. Besides microstructural parameters of investigated materials using the SEM images strength characteristics in compression and in tension were also quantified.

Since a large part of the hydropower structures in Sweden was built in the 1950s and 1960s, many of them are slowly but surely exhibiting deterioration. The hydropower companies are facing big challenges and are consequently investing in effective repairing methods since a hydropower structure failure could pose serious consequences and dangers to people, the environment, and the community. Many structures within hydropower are made of concrete and the demands on the new supplementing concrete are high. Concrete with the potential to meet these high demands is the pre-placed aggregate concrete, which has shown promising results regarding its mechanical properties in previous studies. For this reason, this type of concrete is of interest to investigate. The focus has not been on optimizing the pre-placed aggregate concrete for full-scale productions. Instead, the main objectives of this master thesis were to study and analyze the mechanical properties of this type of concrete, such as shrinkage, compressive strength, splitting tensile strength, freeze-thaw resistance and moreover investigate parameters of importance in the mix design to obtain a homogenous and easy flowing grout that successfully could fill the voids between the coarse aggregates. The investigations were carried out by laboratory experiments in the research and laboratory facilities of Vattenfall in Älvkarleby. The mix design of the grout was developed using the methods and requirements stated in the American Society for Testing and Materials, ASTM standards, and The Swedish Institute for Standards, SiS. A total of 15 grout-mixes were made. However, only the last five were used to cast specimens as the air content was insufficient in the first ten. The results indicated that it is necessary to replace the air-entraining admixture with microspheres in order for the pre-placed aggregate concrete to meet the requirements in exposure class XF3 and XC4. The scaling of the pre-placed aggregate concrete was less than 0.1 kg/m2 at 56 cycles, and thus, the freeze-thaw resistance was classed as very good. Moreover, the use of slag considerably reduced the bleeding of the grout and also improved the casting results. However, on the other hand, it increased the shrinkage of the pre-placed aggregate concrete. An efficiency factor of 0.6 proved to be too low since the compressive strength of the specimen with slag was approximately 50 % higher than the ones without. Furthermore, the shrinkage of the pre-placed aggregate concrete was after 63 days found to be lower than that of the conventional concrete. Also, the compressive strength of the pre-placed aggregate concrete without slag proved to be approximately 15 % lower than that of conventional concrete. Additionally, vibration during casting was found to increase the compressive strength of the pre-placed aggregate concrete and also improved the casting results. Low bleeding, combined with a high discharge time of approximately 45 seconds for 1.7 liters of grout, generated the best casting results. The results from the investigations have shown that this type of concrete has great potential. However, actions and further investigations should be made to see whether changing the fine aggregate size to a smaller one improves the ability of the grout to penetrate the voids between the coarse aggregates. Moreover, pump injection of the grout should be tested instead of pouring it over the coarse aggregates to see whether it improves the casting results and the mechanical properties. / Då en stor del av vattenkraftsdammarna i Sverige byggdes på 1950 och 1960-talet börjar många av dessa sakta men säkert brytas ner. Vattenkraftföretagen står inför stora utmaningar och investerar följaktligen i effektiva reparationsmetoder då dammbrott skulle kunna få allvarliga konsekvenser för människor, den omgivande miljön och för samhället. Flertalet konstruktioner inom vattenkraften är gjorda av betong och kraven på den nya kompletterande betongen är höga. En betong med potentialen att möta och uppfylla dessa höga krav är injekteringsbetongen som i tidigare studier uppvisat lovande resultat beträffande dess mekaniska egenskaper. Med anledning av detta är injekteringsbetongen av intresse att undersöka. Fokus har inte varit på att optimera injekteringsbetongen i syfte att genomföra fullskaliga försök. Istället har huvudsyftet med detta examensarbete varit att studera och analysera injekteringsbetongens mekaniska egenskaper såsom krympning, tryckhållfasthet, spräckhållfasthet, frostbeständighet samt undersöka viktiga parametrar i skapandet av ett homogent och lättflytande cementbruk som med god framgång kunde fylla ut hålrummen mellan grova ballasten. Undersökningarna utfördes genom laboratorieförsök på Vattenfalls betonglaboratorium i Älvkarleby. Vidare har skapandet och utvecklandet av bruket utförts i enlighet med metoder och krav angivna i American Society for Testing and Materials, ASTM standards, samt i Svenska institutet för Standarder, SiS. Totalt gjordes 15 bruksblandningar, dock användes enbart de sista fem till gjutning av provkroppar då lufthalten visade sig vara för låg i dem första tio. Resultaten indikerade på att det är nödvändigt att ersätta luftporbildare med mikrosfärer för att erhålla en lufthalt som uppfyller kraven för betong i exponeringsklass XF3 samt XC4. Injekteringbetongens avflagning efter 56 dygn var mindre än 0.1 kg/m2 och frostbeständigheten kunde därmed klassas som mycket god. Användningen av slagg minskade cementbrukets vattenseparation avsevärt och bidrog även till förbättrade gjutresultat. Dock bidrog det å andra sidan till en ökad krympning hos injekteringsbetongen. En effektivitetsfaktor på 0.6 visade sig vara för låg då injekteringsbetongen med slagg hade en cirka 50 % högre tryckhållfasthet än dem utan. Dessutom visade sig injekteringsbetongens krympning vara mindre än den konventionella betongens efter 63 dagar. Tryckhållfastheten hos injekteringsbetongen utan slagg uppvisade även en cirka 15 % lägre tryckhållfasthet än den konventionella betongens. Vibrering under gjutning visade sig höja tryckhållfastheten hos injekteringsbetongen samt förbättra gjutresultaten. En låg vattenseparation i kombination med en flödestid på cirka 45 sekunder för 1.7 liter bruk visade sig ge bästa gjutresultaten. Resultaten från laboratorieförsöken har visat på att injekteringsbetongen besitter stor potential. Dock bör ytterligare undersökningar genomföras för att bedöma huruvida en mindre ballastfraktion för sanden påverkar brukets förmåga att penetrera den grova ballasten. Vidare bör bruket pumpas in istället för att hällas över den grova ballasten, detta för att se huruvida gjutresultaten samt de mekaniska egenskaperna hos injekteringsbetongen skulle förbättras.

Soil-cement is an integral part of pavement design, especially in areas that are aggregate deprived, such as Mississippi. Current designs are reliant on the relationship of unconfined compressive strength (UCS) to other mechanical properties. The other properties discussed in this dissertation are Modulus of Elasticity (E), Indirect Tensile Strength (St), and Modulus of Rupture (MOR). This dissertation includes a comprehensive review of past design methods and mechanical property relationships. While some mechanical property relationships were shown to be well understood (i.e. St to UCS), others were not as accurate, especially for the later life mechanical properties (i.e. MOR to UCS and E to UCS). This dissertation investigates the Plastic Mold (PM) Compaction (PM) Device and its ability to measure mechanical property relationships (UCS, E, St) for soil-cement as well as different materials, such as lime stabilized subgrade and Cold in Place Recycling (CIR) stabilized with cement. These mechanical property relationships were compared to soil-cement beam specimens, which are capable of being tested for the four previously mentioned mechanical properties from an individual specimen. Finally to have a better understanding of the later life mechanical properties and their relationships, PM and beam specimens were exposed to elevated temperatures to forecast out how these properties interrelate over time. These mechanical property values and relationship were then compared to Mississippi field cores ranging from 10 to 54 years old. These protocols, beam and elevated curing, were able to replicate what was seen for pavement cores that were extracted after decades of service. Over 1300 specimens were testing showing how these mechanical properties interacted from early ages and throughout a pavement’s life.

[pt] Alguns dos problemas mais comuns relatados durante a perfuração de poços petrolíferos, como a instabilidade, a perda de circulação e o colapso das paredes, podem ser evitados com o acesso em tempo real, dentre outros, à resistência à com-pressão não confinada das rochas. Os métodos mais usuais de estimativa da resis-tência não confinada apresentam três principais restrições quanto à aplicação em tempo real: i) a perfilagem em tempo real pode não ocorrer ao longo de toda a tra-jetória do poço e é mais costumeira em profundidades próximas ao reservatório; ii) a obtenção de amostras provenientes do poço para ensaios de laboratório é prática custosa e pouco usual e; iii) as informações relativas à geometria da broca são res-tritas aos fabricantes. Nesse contexto, esta dissertação tem como foco a adaptação de um método de estimativa da resistência não confinada para tornar possível a aplicação em tempo real, partindo da hipótese de que a perfuração é fundamental-mente controlada pela interação entre a broca e a formação rochosa e que a resis-tência à compressão confinada está relacionada a uma parcela da energia mecânica específica. A metodologia desenvolvida foi aplicada em um poço, testada em outros nove poços e será implementada no programa de estabilidade SEST TR 2.0. Sa-bendo que a resistência não confinada é função da coesão e do ângulo de atrito, a coesão da formação rochosa também foi calculada. Este estudo conclui que é pos-sível estimar ambas as propriedades mecânicas em tempo real dispondo apenas dos parâmetros operacionais de perfuração. / [en] Some of the most common problems reported during well drilling, such as instability, loss of circulation and wellbore collapse can be avoided with real-time access, among others, to the unconfined compressive strength of rocks. The most usual methods for estimating unconfined compressive strength have three main re-strictions regarding their real time application: i) real-time logging may not occur along the entire trajectory of the well and is more common at depths close to the reservoir; ii) obtaining samples from the well for laboratory tests is costly and un-usual practice and; iii) information regarding drill bit geometry is restricted to man-ufacturers. In this context, this research focuses on the adaptation of an unconfined compressive strength estimation method to make real-time application possible, based on the hypothesis that drilling is fundamentally controlled by the interaction between the drill bit and rock formation and that the confined compressive strength is related to a portion of the mechanical specific energy. The developed methodol-ogy was applied in one well, tested in nine other wells and will be implemented in the SEST TR 2.0 stability program. Knowing that unconfined compressive strength is a function of cohesion and friction angle, the cohesion of the rock for-mation was also calculated. This study concludes that it is possible to estimate both mechanical properties in real time using only drilling data.

The dominating support method for hard rock tunnels today is use of fibre reinforced shotcrete in combination with rock bolts. The fibre reinforced shotcrete secures smaller blocks, while rock bolts are used to support larger blocks in the rock. Application of shotcrete is done by spraying against the rock surface using compressed air. The use of accelerators result in fast strength development and adhesive properties, which are two characteristics of great importance when constructing tunnels. This thesis aims at increasing the understanding of climate impact from fibre reinforced shotcrete in tunnel construction. The focus is on reducing the climate impact with two methods: reducing the share of cement in the shotcrete mixture through substitution with addition materials and using better test methods for fibres. Cement is one of the most important ingredients in concrete, however also the largest contributor to CO2 emissions. Reducing the cement amount is therefore a way of reducing the emissions of concrete. In addition, when testing the performance of fibres, different methods can lead to a spread in the results, causing an overuse of fibres in the shotcrete. First, the thesis investigated the use of alternative binder materials, especially Ground Granulated Blast Furnace Slag (GGBS), as a substitute for cement. Experimental testing was performed in a laboratory to evaluate the compressive strength for shotcrete with different amounts of GGBS. Testing was performed after one and seven days in order to evaluate the early strength. Second, the thesis investigated the use of fibre reinforcement and the possibilities of reducing the fibre dosage when changing fibre type and test method. Numerical modelling was performed for two test methods, beam and panel testing, based on experimental data. The thesis evaluated the environmental performance in terms of Global Warming Potential for both fibres and binder. The results show that substituting cement with GGBS has the largest potential to lower the CO2 emissions from fibre reinforced shotcrete. In addition, the fibre dosage can be lowered by changing fibre type, but also test method. Also this lowers the emissions, however the main emissions origins from the binder part. / Den dominerande förstärkningsmetoden för tunnlar i hårt berg idag är fiberarmerad sprutbetong i kombination med bergbultar. Den fiberarmerade sprutbetongen säkrar mindre block, medan bergbultar säkrar större block från att falla ner. Sprutbetongen appliceras genom sprutning direkt mot bergytan men hjälp av tryckluft. Användning av acceleratorer medför snabb hållfasthetsutveckling och vidhäftande egenskaper, vilka är av stor vikt vid tunnelkonstruktion. Syftet med examensarbetet är att öka förståelsen för klimatpåverkan från fiberarmerad sprutbetong i tunnelkonstruktion. Fokus är att undersöka minskningar i klimatpåverkan med två metoder: minska andelen cement i betongblandningen genom ersättning med alternativa material och använda bättre testmetoder för fibrer. Cement är en av de viktigaste ingredienserna i betong, men också den största bidragande faktorn till koldioxidutsläpp. Minskning av andelen cement är därför ett sätt att reducera utsläppen från betong. Dessutom kan valet av testmetod ha stor påverkan på vilken dosering av fibrer som krävs. Examensarbetet undersökte först användningen av alternativa bindemedelsmaterial, speciellt granulerad masugnsslagg, i sprutbetong som ett ersättningsmaterial till cement. Experiment i labb utfördes för att utvärdera tryckhållfastheten för gjuten sprutbetong med olika andelar granulerad masugnsslagg. Testning genomfördes efter en respektive sju dagar för att utvärdera hur slagg påverkar den tidiga hållfastheten. Användningen av fiberarmering och möjligheten att reducera fiberinnehållet vid byte av fibersort och testmetod undersöktes sedan. Numerisk modellering genomfördes för två testmetoder, balk- och plattest, baserat på experimentell data. Examensarbetet utvärderade klimatpåverkan i termer av Global Warming Potential, GWP, för både fibrer och bindemedel i sprutbetong. Resultaten visar att ersättning av cement med granulerad masugnsslagg har den största potentialen att minska koldioxidutsläppen från fiberarmerad sprutbetong. Dessutom kan fiberdoseringen minskas genom ändrad fibertyp samt ändrad testmetod, vilket också minskar utsläppen. Emellertid härstammar de största utsläppen från bindemedlet.