This master thesis presents the effects of fly ash on the properties of alkali activated slag concrete, commonly referred as Geopolymer concrete (GPC). Cement manufacturer are major producers of CO2 which negatively affects the environment. Due to the increased construction activities and environmental concern, it is necessary to introduce alternative and eco-friendly binders for concrete. Slag and fly ash based concrete, which is by-product from industrial waste, is probably the best replacement for OPC concrete due to less or nil environmental issue. Most of the researchers have already concluded that slag and fly ash can be used as binders in concrete by activating them with alkali activator solution (e.g. by sodium silicate or sodium carbonate). In the present work concretes were produced by varying the proportion of slag to fly ash (40:60, 50:50, 60:40 & 80:20); amount of alkali activators (5, 10 & 14) and chemical modulus of sodium silicate (Ms) (0.25, 0.5 & 1).  Setting times and compressive strength values were evaluated. Results showed that decrease in fly ash content irrespective of % of alkali activators and alkali modulus (Ms), the compressive strength was increasing and setting time was getting shorter. The produced concretes showed increasing compressive strength with increase in % of alkali activator for Ms 0.5 and 1, while for Ms=0.25 the strength was decreasing with increase in % of alkali activators. From this it can be concluded that, Ms=0.5 was the optimum point below which the reaction got slower. Based on the initial investigations, mix S8:F2-SS10(1) and S8:F2-SS10(0.5) showed most promising results in terms of fresh and hardened concrete properties and were easy to handle. Consequently, the above mentioned mixture was chosen to be studied in more detail. The experimental program for these mixes included determination of slump flow, compressive strength (7, 14, 28 days) and shrinkage (drying and autogenous). The results shows that, strength increased with time and comparatively mix with Ms=0.5 showed higher compressive strength than mix with Ms=1, due to higher alkalinity of the pore solution. Mix with Ms=1 showed higher drying shrinkage compared to mix with Ms=0.5, which was explained by higher alkalinity of the solutions (Ms=0.5) leading to rapid formation of aluminosilicate gel. Autogenous shrinkage appeared to be higher for mix with Ms=0.5. This was associated with lower modulus which leads to densification of concrete microstructure at early ages. Pore diameter decrease and the water trapped in the pores exerted increasing tensile stress resulting for higher autogenous shrinkage.

A reação álcali-agregado é uma manifestação patológica diretamente ligada à seleção dos materiais (cimento, agregados miúdo e graúdo, água e aditivos) que pode comprometer a durabilidade das estruturas de concreto, uma vez que a interação desses materiais e as condições ambientais é que vão conferir ao concreto determinadas propriedades ligadas à sua vida útil. A reação entre os hidróxidos alcalinos solubilizados na fase líquida dos poros dos concretos e alguns agregados reativos é lenta e resulta em um gel que, ao se acumular em vazios do concreto e na interface pasta-agregado, na presença de água, se expande, exercendo pressão interna no concreto. Ao exceder a resistência à tração do concreto, a pressão interna pode promover fissurações. A reação álcali-agregado requer a atuação conjunta de água, agregado reativo e álcalis. Sua prevenção pode ser feita a partir da eliminação de um dos fatores, ou seja, a partir do emprego de agregados inertes ou de cimentos com baixos teores de álcalis ou isolamento da umidade. Na impossibilidade de eliminar um dos fatores, medidas preventivas devem ser tomadas para o emprego de agregados reativos em obras de construção civil. Entre essas, destacam-se a utilização de cimentos com baixos teores de álcalis ou a de cimentos com adições ativas mitigadoras da reação álcali-agregado: escória de alto-forno, cinza volante, metacaulim e sílica ativa, que foi o objeto de pesquisa do presente trabalho. No programa experimental foram analisados dois tipos de agregado potencialmente reativos com os hidróxidos alcalinos: EDVDOWR e PLORQLWR_ JUDQtWLFR. O primeiro, proveniente de rocha ígnea, tem como constituintes deletérios vidro, clorofeíta, calcedônia (sílica criptocristalina), que dará origem à reação do tipo iOFDOL_VtOLFD. O agregado milonito granítico provém de rocha metamórfica, tem como constituintes deletérios quartzo microgranular, quartzo recristalizado, quartzo com extinção ondulante e quartzo e feldspato deformados, que dará origem ao tipo de reação iOFDOL_VLOLFDWR. Com o objetivo de avaliar a eficiência de adições ativas em mitigar as reações, os agregados foram combinados com 16 cimentos com adições ativas. Escória de alto-forno foi adicionada a 15%, 30%, 45% e 60% e cinza volante, a 10%, 15%, 25% e 35%, teores normalmente encontrados nos cimentos brasileiros. Metacaulim foi adicionada a 5%, 10%, 15% e 20%, e sílica ativa, a 5%, 10% e 15%, teores representativos da faixa normalmente adicionada diretamente a concretos. Todos os materiais utilizados foram caracterizados química, física e mineralogicamente, incluindo a análise petrográfica dos agregados. As barras de argamassa foram analisadas ao MEV, microscópio óptico de luz transmitida, realizaram-se ensaios de porosimetria por intrusão de mercúrio e análises térmicas para quantificar a teor de portlandita residual, e determinou-se o teor de álcalis dentro das barras após a realização dos ensaios para verificar a migração de íons de sódio. Os resultados indicam que a eficiência das adições ativas varia de acordo com a composição química e mineralógica das adições, da proporção desse material no cimento, e do grau de reatividade do agregado. / The alkali-aggregate reaction is a pathologic manifestation that can induce the premature distress and loss in serviceability of concrete structures affected. It is directly associated to the selection of materials (cement, coarse and fine aggregates, water and additives), as the interaction between these materials and environmental condition will grant the concrete some of the properties related to its service life. The slow reaction between alkali hydroxides soluble in the liquid phase within concrete pores and reactive aggregates gives rise to a gel that piles up within concrete voids and the aggregate-paste interface. In presence of water, the gel expands and exerts internal pressure in the concrete. When the internal pressure exceeds the tensile strength, cracking may come up as result. The alkali-aggregate reaction requires the action of water, reactive aggregate and alkalis altogether. Prevention can be carried out by eliminating one of these factors, i.e. employing either inert aggregates or lowalkali cements, or keeping the concrete away from moisture. Otherwise, preventive measures must be taken when reactive aggregates are used in civil construction works, such as the use of low-alkali cements or composite cements bearing alkaliaggregate- reaction mitigating admixtures: blast-furnace slag, fly ash, metakaolin and silica fume, which are the object of the present research. The experimental work included the analysis of two potentially reactive aggregates to alkali hydroxides: basalt and granite milonite. The igneous basalt carries deleterious constituents such as glass, chloropheite (cryptocrystalline silica), that will give rise to the DONDOL_VLOLFD type reaction while the metamorphic granite milonite carries micro granular, recrystallized, undulate-extinction-bearing quartz and deformed feldspar grains, that give rise to DONDOL_VLOLFDWH type reaction. Aiming at evaluating how efficient in mitigating these reactions the active admixtures are, these aggregates were mixed with 16 composite cements. The contents of admixtures followed those usually found in Brazilian industrial cements for blast-furnace slag (15%, 30%, 45%, 60%) and fly ash (10%, 15%, 25%, 35%), and those generally added directly to concrete for metakaolin (5%, 10%, 15%, 20%) and silica fume (5%, 10%, 15%). All materials were characterized for their chemical composition, physical properties and mineralogy. Petrography was carried out on the aggregates. The mortar bars were analyzed at the scanning electronic and transmitted-light optical microscopes. Mercury-intrusion porosimetry and thermal analyses were carried out to quantify residual portlandite. The alkali content within the bars was determined in order to verify migration of Na+ ions. The results show that the efficiency of active admixtures varies according to their chemical and mineralogical composition and proportioning in cement, and to the aggregate reactivity.

A crescente preocupação ambiental e a atual crise energética fazem com que indústrias, de um modo geral, intensifiquem esforços para maximização de processos de produção e reutilização de subprodutos gerados. Na siderurgia a produção do aço é realizada por meio da extração do minério de ferro adicionando-se fundentes, gerando como subproduto uma ganga em forma de escória de alto forno. Na presente pesquisa foram compostas misturas de concreto compactado com rolo CCR visando o emprego como base de pavimentos, utilizando três diferentes materiais de granulometria miúda: areia natural, areia industrial e escória granulada de alto forno (com dimensão máxima de 4,8 mm) nas quantidades de 50 % e 100 %; para fins de análise da influência destas diferentes areias foram confeccionados corpos de prova cilíndricos e prismáticos moldados na umidade ótima e no ramo seco da curva de compactação. Foram investigados parâmetros referentes à umidade de compactação, massa específica, resistências à tração indireta e à tração na flexão, módulos de elasticidade por pulso ultrassônico, além de módulos de elasticidade estáticos obtidos a partir de curvas tensão-deformação e por analogia de Möhr (medida de flecha em vigotas em flexão). Visando avaliar a aplicabilidade dos CCR estudados, em especial aquele com escória, foi utilizado o programa computacional MnLayer (para análise de tensões em pavimentos asfálticos) empregando camada de base rígida em CCR para estruturas de pavimentos sujeitos à ação de cargas do tráfego de veículos rodoviários, portuários e aeroportuários, observando a influência dos três tipos de agregados miúdos no nível de tensões da camada cimentada, o que depende em grande parte do módulo de elasticidade da camada de base. Observou-se queda nas resistências dos CCR quando da incorporação de 50 % ou 100 % de escória granulada; por outro lado, essas misturas apresentaram ganhos de resistência em idades mais avançadas em comparação a misturas que empregaram areias natural ou industrial. O módulo de elasticidade dos CCR, com a presença da escória, parcial ou total como fração areia, em geral decresceu à exceção de seu emprego em conjunto com areia natural. As misturas com escória granulada, do ponto de vista de análise mecanicista, resultaram em exigências de maiores espessuras do material, o que não pode fazer tal mistura economicamente viável em qualquer situação, para os casos de misturas com 100 % de escória granulada de alto forno e com fração mista de areia natural e escória. / The increasing environmental concerns as well as energy sources shortage leads industry to consider both optimization of production processes and sustainable use and disposal of its by-pass products. In siderurgical steel manufactures the most common by-pass product is the blast furnace slag with emphasis to its granulated shape. This study considered the evaluation of rolled compacted concretes (RCC) mixtures containing natural or industrial sands as well as such slags at 50% and 100% (with maximum diameter of 4.8 mm) as candidates for pavement base layers. The analysis considered laboratory compaction tests in order to verify the influence of such sands on concrete physical parameters as bulk density and optimum moisture content. Evaluation of mechanical parameters as indirect tensile strength, flexural strength, ultrasonic modulus of elasticity and static modulus of elasticity were carried out as part of the study. Through mechanistic analysis using the elastic layered theory-based computational program MnLayer it was possible to verify implications of each RCC mixture design on pavement thickness and tensile stresses in cemented base layers, in consideration of highway, harbor and airport vehicles. Loss of resistance was verified for RCC mixtures at 50% and 100% slag sand; on the other hand such mixtures have improved its strengths at advanced ages (180 days) compared to the other sands. The modulus of elasticity also decreased for mixtures containing slag sands with exception to the blend of natural and slag sand. Under the mechanistic stand point slag sand mixtures requires thicker base layers in pavements that could lead, depending on several factors, to less cost-effective results in the case of 100% slag sands mixtures and blend (50%-50%) natural and slag sands mixtures.

O objetivo desta tese foi o estudo da influência do aditivo redutor de retração (SRA) e o aditivo compensador de retração (SCA) em argamassas e pastas de cimento de escória ativada com silicato de sódio. A metodologia foi centrada na análise da retração por secagem e autógena, com o estudo de outras características que influenciam no fenômeno da retração, como as propriedades mecânicas. Para o avanço no conhecimento do efeito dos aditivos no comportamento do cimento de escória, foi caracterizada a microestrutura com a determinação da análise por termogravimetria, porosimetria e difração de raios X. Neste estudo foram empregados os seguintes teores de aditivo, porcentagem relativa à massa de aglomerante: 0,5%, 1%, 1,5% e 2% do aditivo SRA e 5%, 10% e 15% do aditivo SCA. Para a análise da influência da relação a/agl foram empregadas três teores: 0,40, 0,48 e 0,56. No estudo das amostras de referência, sem a utilização de aditivo, observou-se que o aumento da relação a/agl causa o aumento da retração por secagem e da retração autógena do cimento de escória ativada. A diminuição da resistência mecânica com o aumento da relação a/agl, o que torna o esqueleto sólido mais susceptível à deformações, e o aumento das tensões capilares, em razão do aumento da quantidade de água livre para ser evaporada, são os principais fatores para o aumento da retração por secagem. No caso da retração autógena, seu aumento é atribuído ao aumento da auto-secagem com o aumento do volume de poros com diâmetro na faixa de mesoporos, além da diminuição da resistência mecânica. O aditivo redutor de retração (SRA) conseguiu reduzir a retração por secagem em percentuais de 40% até 74% aos 28 dias, no entanto, este tipo de aditivo não obteve êxito no combate a retração autógena. Com relação à resistência mecânica, o aditivo SRA causou a redução de até 40%, efeito atribuído à diminuição do grau de hidratação e retardo do refinamento da porosidade. O aditivo compensador de retração (SCA) amenizou a retração por secagem e a retração autógena, reduzindo em até 64% e 70%, respectivamente, porém reduziu em até 60% a resistência mecânica do cimento de escória ativada. Com relação à microestrutura, o aditivo SCA diminuiu o grau de hidratação e aumentou a porosidade total, com o aumento da proporção do volume de macroporos. / The aim of this research was the study of the influence of shrinkage reducing admixture (SRA) and shrinkage compensating admixture (SCA) in mortars and pastes of blast furnace slag activated with sodium silicate. The method was centered in the analysis of free drying and autogenous shrinkage, with other characteristics that affect the shrinkage, as the mechanical properties. The microstructure behavior was accomplished with thermogravimetry (TG), mercury intrusion porosimetry (MIP) and X-ray diffraction (XRD). The samples were prepared with 0,5%, 1%, 1,5% and 2% of SRA admixture and 5%, 10% and 15% of SCA admixture, by binder mass. The effect of water/binder ratio was accomplished in three contents: 0,40, 0,48 and 0,56. In the reference mixtures, without admixtures, it was observed that an increase of water/binder ratio incurs in an increase of drying and autogenous shrinkage of alkali activated slag. The explanations for drying shrinkage behavior are the decrease of mechanical strength as consequence of water/binder increase, that turns the porous structure more susceptible to deformations, and the increase of the capillary tensions, attributed to the increase of free water to be evaporated. The increase of autogenous shrinkage with water/binder ratio is attributed to the increase of pore volume with diameter in the mesopores range, besides the decrease of the mechanical strength. The shrinkage reducing admixture (SRA) diminish drying shrinkage of 40% up to 74% at 28 days, however, this type of admixture was not capable to combat the autogenous shrinkage. About mechanical strength, the SRA admixture incurs in a decrease up to 40% of compression strength that it was attributed to the decrease of the hydration degree and retard of pore size refinement. The shrinkage compensating admixture (SCA) softened drying and autogenous shrinkage, reducing in up to 64% and 70%, respectively. However, the SCA admixture decreases in up to 60% mechanical strength of alkali activated slag. About microstructure, SCA admixture reduced the hydration degree and it increased the total porosity, with the increase of macropores volume.

In well cementing, the cement slurry is exposed to the conditions far different than those of ordinary Portland cement (PC) used in construction. After placement, hardened cement paste should preserve integrity and provide zonal isolation through the life of the well. American Petroleum Institute (API) Class G cement is the most common cement type used in various well conditions. Class G cement has a high degree of sulfate resistance which makes it more stable than PC when subjected to the compulsive well conditions. Ground granulated blast furnace slag (GGBFS) blended cement has a long history of use in the construction industry, but is not extensively used in well cementing applications. This study presents an experimental program to investigate the applicability of CEM I and GGBFS blended cement pastes in the well cementing industry. Class G cement and blends of CEM I and GGBFS with the proportions (80:20), (60:40), (40:60) and (20:80) are prepared with same water/cement ratio (0.44) as restricted for Class G cement in API Specification 10A to be tested. The cement pastes are cured for ages of 1 day, 7 days and 28 days at 80

Slurry walls have been widely used for more than 25 years to control the migration of contaminants in the subsurface. In the USA, vertical barriers are mostly constructed of soil-bentonite using the slurry trench method of construction. In this method, sodium bentonite is mixed with water to form a viscous slurry that is pumped into a trench during excavation to maintain the trench stability. The stable trench is then backfilled with a mixture of soil and slurry having a consistency of high slump concrete. These barriers have been designed primarily for low permeability, generally less than 10&minus / 9 m/s. Some investigations have pointed toward improved performance using admixtures that would provide low permeability. In this study, Soma thermal power plant fly ash, granulated blast furnace slag, lime, and steel slag are used as admixture to improve the performance of slurry walls. Permeability, compressive strength, slump, compressibility properties of the mixtures were found and checked for the minimum requirements. According to the findings of this study, granulated blast furnace slag (GGBS), fly ash and steel slag can be used at certain percentages and curing periods as additive in cement-bentonite barrier wall construction. Permeability of specimens having fly ash decreases by increasing fly ash content. Mixtures having 50 % of GGBS type I with 5 % of lime and 9% bentonite content gave acceptable results in 28 days of curing time. Specimens including 50 % of GGBS type II with 5 % of lime and 9% bentonite content gave the higher permeability value in 28 days of curing time with respect to GGBS type I. In addition, most of the mixtures prepared by steel slag gave the acceptable permeability values in 28 days of curing period. Unconfined compressive strength of all mixtures increase by increasing curing time. Cc, Cr, Cv, kcon values were found from consolidation test results. Permeability values found from consolidation tests are 10 times to 100 times higher than flexible wall k results for the same effective stress of 150 kPa. Generally, mv values are decreasing with increasing curing time. As mv decreases, D increases.

Highly polluted urban storm water from e.g. highways can contain large amounts of heavy metals that may cause harm if they are discharged into recipients. To remove the heavy metals a possible low-cost method that does not require much maintenance, could be the use of reactive filters with filter materials consisting of industrial residues or other cheap mineral based materials. Dissolved metal ions are removed by reactive filters through the processes of ions binding to active sites on the surface of the filter materials, or by formation of insoluble precipitates. The ability of CaO-treated granulated blast-furnace slag, iron oxide coated sand, olivine and nepheline to remove seven heavy metals (Cr, Cd, Cu, Ni, Zn, Pb and Hg) from urban storm water was studied. Initially batch experiments were performed where the effect of pH, dissolved organic carbon (DOC) and dissolved ions on the adsorption efficiency was studied. The experiments were conducted with urban storm water and with a reference solution (10 mM NaNO3), both containing the same concentration of heavy metals (approx. 1 μM). The two materials with the best results were further investigated in a column study, where the capacity of the filter was tested. Chemical equilibrium calculations using the program Visual MINTEQ were performed in order to assess the role of precipitation as a mechanism for removal. The results show that the blast-furnace slag was the most effective filter material and that it has great potential to be used as a heavy metal remover. Also the iron oxide coated sand worked satisfactory. The highest degree of removal was obtained for lead, cadmium and nickel, for which the removal efficiency exceeded 90% after a load of 300 times the water volume in the columns. For some metals, mainly copper, chromium and mercury the dissolved organic matter affected the removal negatively. The chemical mechanisms causing the removal are specific adsorption to the surfaces of the materials, and for the blast-furnace slag probably precipitation of insoluble metal sulfides. / Starkt förorenat dagvatten som rinner av från exempelvis motorvägar, kan innehålla betydliga mängder tungmetaller som kan orsaka skada om de kommer ut i omgivande vattendrag. En billig metod för tungmetallavskiljning, som inte kräver så mycket underhåll, skulle kunna vara att använda reaktiva filtermaterial bestående av restprodukter eller andra mineraliska lågkostnadsmaterial. Reaktiva filter fungerar som metallavskiljare genom att de lösta metalljonerna binder till ytgrupper på filtermaterialen eller att svårlösliga utfällningar bildas. Förmågan att avskilja sju tungmetaller (Cr, Cd, Cu, Ni, Zn, Pb och Hg) ur dagvatten har undersökts för fyra mineraliska filtermaterial, kalciumoxiddopad masugnsslagg, järnoxidsand, olivin och nefelin. Studien inleddes med skakförsök där adsorptionens pH-beroende undersöktes. Försöken gjordes dels med dagvatten, dels med en referenslösning (10 mM NaNO3) med samma tungmetallkoncentration (ca 1μM). Detta gjordes för att studera effekter av löst organiskt material och andra ligander på adsorptionen. Därefter testades de material som uppvisat bäst resultat i skakförsöket i kolonnförsök, ett försök som mer efterliknar en praktisk tillämpning och där filtrets kapacitet kan studeras. Genom kemiska jämviktsberäkningar med programmet Visual MINTEQ var det möjligt att undersöka om bildningen av svårlösliga metallutfällningar bidrog till metallavskiljningen. Resultaten visar att slaggen var det effektivaste filtermaterialet och att detta har stor potential att användas för avskiljning av tungmetaller. Även järnoxidsanden fungerade tillfredsställande. De metaller som avskiljdes bäst var bly, kadmium och nickel, för vilka avskiljningen var > 90 % i kolonnförsöket efter en belastning motsvarande 300 gånger vattenmängden i kolonnerna. För vissa metaller, främst koppar, krom och kvicksilver, försämrades avskiljningen betydligt när löst organiskt material fanns närvarande. Mekanismerna som står för avskiljningen är till störst del adsorption till grupper på filtermaterialens ytor, men bildning av svårlösliga metallsulfider är också tänkbar för slaggen.

In calcium aluminate cement (CAC) systems the hydration process is different than portland cement (PC) systems. The hydration products of CAC are subjected to conversion depending on temperature, moisture, water-cement ratio, cement content, etc. Consequently, strength of CAC system can be seriously reduced. However, presence of other inorganic binders or additives may alter the hydration process and improve various properties of CAC based composites. The objective of this study is to investigate the temperature effect on the behaviour of CAC based composite binders. Throughout this research, several combinations of CAC-PC, CAC-gypsum, CAC-lime, CAC-ground granulated blast furnace slag (CAC-GGBFS) were studied. These CAC based composite binders were subjected to seven different curing regimes and their strength developments were investigated up to 210 days. In addition, the mechanism of strength development was examined by XRD analyses performed at 28 and 210 days. Finally, some empirical relationships between strength-time-curing temperatures were formulated. Experimental results revealed that the increase in ambient temperature resulted in an increase in the rate of conversion, thereby causing drastic strength reduction, particularly in pure CAC mix. It has been observed that inclusion of small amount of PC, lime, and gypsum in CAC did not induce conversion-free CAC binary systems, rather they resulted in faster conversion by enabling rapid formation of stable C3AH6 instead of metastable, high strength inducing CAH10 and C2AH8. On the other hand, in CAC-GGBFS mixes, the formation of stable straetlingite (C2ASH8) instead of calcium aluminate hydrates hindered the conversion reactions. Therefore, CAC-GGBFS mixes, where GGBFS ratio was over 40%, did not exhibit strength loss due to conversion reactions that occurred in pure CAC systems.

In the production of cement, to increase the cement/clinker ratio and decrease CO2 emission, the most important alternative is to produce mineral admixture incorporated cements (CEM II-III-IV-V) instead of portland cement (CEM I). These cements are usually produced by intergrinding the portland cement clinker and the mineral admixtures. However, the difference between grindabilities of the different components of such cements may cause significant effects on the particle size distribution and many other properties. For this reason, separate grinding of additives and clinker may be thought as an alternative. In this study, the effects of intergrinding and separate grinding on the particle size distribution and consequently on the strength of portland composite cements which contained natural pozzolan (trass), granulated blast furnace slag (GBFS) and limestone besides portland cement clinker were studied.

Properly proportioned, placed and cured concrete can be durable under most conditions. However, deterioration of concrete does occur under certain environments. One of the problems that affect the durability of hardened concrete is delayed ettringite formation (DEF) which is an important problem encountered in precast concrete industry where high temperature curing is applied. Although there had been many researches on DEF, there are still many uncertainties about its chemistry and mechanism. In this study, the effects of partial cement replacement by different mineral admixtures (trass, blast furnace slag and fly ash), SO3/Al2O3 molar ratio and specific surface area of cement on DEF were investigated. For this purpose, 9 groups of control cements were prepared with 3 different specific surface areas and 3 different SO3/Al2O3 molar ratios. Different amounts of mineral admixtures were blended with the control cements. High temperature curing was applied to the cement pastes and the expansions of these pastes were measured periodically for 240 days. v The experimental results obtained were interpreted for a comparative analysis of the effects of the afore-mentioned parameters.