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.

To foster the practical development of constructed wetlands used for wastewater treatment in Turkey, a pilot-scale subsurface constructed wetland system (90 m2) was designed to treat the domestic wastewater produced by 60 PE living in the residential area of METU. In summer 2001, two parallel sets of hybrid wetland systems (vertical flow connected with horizontal flow) with identical design configuration, but with different fill media (blast furnace granulated iron slag and gravel) were built on the old sludge-drying bed of the abandoned wastewater treatment plant of METU, which has not been operating since the 1990s. Wetland cells were planted with common reed (Phragmites australis). The main objective of this research was to quantify the effect of different filter media on the removal performance of subsurface flow constructed wetlands in the prevailing climate of Ankara. Thus, slag-filled and gravel-filled vertical flow wetlands were operated identically with pre-settled domestic wastewater (3 m3.d-1) at a hydraulic loading rate of 110 mm.d-1 for 12 months, intermittently. According to the first year results, annual average removal efficiencies for the slag and gravel wetland cells were as follows: TSS (63% &amp / 59%), COD (47% &amp / 44%), NH4+-N (88% &amp / 53%), TN (44% &amp / 39%), PO43--P (44% &amp / 1%) and TP (45% &amp / 4%). The slag-filled vertical flow system removed phosphorus and ammonium efficiently than the gravel-filled system due to the differences in physical structures and chemical compositions of the fill media, and the different aerobic and anaerobic environments within the wetland cells. These results indicated that the well-designed constructed wetlands could also be used for secondary and tertiary treatment in Turkey, successfully.

In recent years, scientific studies are carried out to find new refractory material. Having good mechanical properties under very high temperatures, refractories are widely used in industries like iron, steel, glass, cement and pottery. Researches are focused on monolithic refractory making because of their superior properties comparing to conventional firebrick refractories. Providing a mono-block body, having no joints makes the monolithic refractories more durable at elevated temperatures. Easier production and installation are two main points that people are choosing monolithic refractories, thus an economy is made. In this study, for monolithic refractory production, high alumina cement was used as binding material. It is known that the increase in alumina (Al2O3) content increases the high temperature resistance, so that crushed firebrick, having 85% Al2O3 was used as aggregate. Pozzolanic materials, which are silica fume, fly ash, ground granulated firebrick and ground granulated blast furnace slag, were added to improve physical and mechanical properties of mortar. With the addition of steel fibres, change in compressive strength and flexural strength was observed.Superplasticizer was used to understand its behaviour under high temperatures. Portland cement containing mortars were also prepared to make comparison with high alumina cement containing specimens. Specimens were prepared in 5x5x5 cm and 4x4x16 cm prisms. They were cured for one day at curing room, then heated to 105&deg / C and then heated to 1100&deg / C. Weight, size and ultrasound velocity change, compressive strength and flexural strength tests were done to determine physical and mechanical properties of the monolithic refractories, before and after heating. Heated and non-heated specimens were pulverized for microstructural investigation with X-Ray diffraction (XRD) method. Using high alumina cement with 50 &ndash / 60 % granulated blast furnace slag or granulated firebrick, by the weight of cement, and crushed firebrick as aggregate, a satisfactory monolithic refractory material was made. It was observed that, mechanical properties were decreased at the Portland cement used mortars after several times of heating and cooling cycles. Also, it was determined that the microstructure of the high alumina cement containing mortars did not deteriorate much at 1100&deg / C, as long as there was no change observed from the results.

Conselho Nacional de Desenvolvimento Científico e Tecnológico / The study of concrete structures durability necessarily passes by the study of covercrete and by the understanding of the factors that affect the features of this superficial layer. The use of high contents of mineral addictions on the concrete influences meaningfully the resistance of the covering layer to the chemical attack and on the pores structure. This dissertation aimed to analyze, through the obtained results in the tests of capillary water absorption, according to the RILEM TC 116 PCD Recommendation, and to the diffusion of water held following the directives DAN et al (1988) presented by Isaia (1995), based on publications of CSTB, the percolation of water on concrete covering layer, besides co-relating with the resistance to 50 MPa, the total volume of intruding mercury and the critical diameter of the pores. To these analysis perform, prototypes specimens of 75 cm x 20cm x 15cm have been molded with high contents of mineral additions, 70 % of slag and 20% of fly ash, in replacement to the cement mass, with or without addition of 20% of hydrated lime, in mass, and w/cm relationships 0,3 ; 0,4 ; 0,5 besides the reference mix proportion, only with cement and w/cm relationships 0,4; 0,6 e 0,8. The tests of capillary absorption and water diffusion were held, on the 91 and 300 days to execute the comparative study between these two ages, extracted specimens of 10 cm x 20 cm, from the prototypes had been accomplished, being closed to 0, 2,5 e 5,0cm of depth from the surface. After performing the analysis, it has been noticed that the replacement of cement by mineral additions causes a strength reduction to the compression, being it more accentuated in the initial ages and eased as the time passes by. In relation to the coefficients of water absorption and diffusion of the concretes with mineral additions compared to the reference concretes in equality of w/cm and ages, being analyzed the use of additions, meaningful reductions that get to 79% in the absorption and 69% in the diffusion, on the 300 day. When analyzed considering the depth (in equality of w/cm) the layer reduction 3 (5cm) in relation to 1(0,5cm) gets to 55% in the absorption and 31% in the diffusion, on the 300 day, and in the mix proportion with addition of hydrated lime, justifiable by the fact of the hydrated lime stored water helping in the hydrating process producing a more compact matrix. In equality of 50 Mpa compressive strength, the reductions are 86% to the absorption and 70% to the diffusion. It s been noticed, as to the absorption as to the diffusion, a strong co-relation with the intruding total volume and the pores diameter on the 300 day. / O estudo da durabilidade das estruturas de concreto passa, necessariamente, pelo estudo do concreto de cobrimento e pelo entendimento dos fatores que afetam as características dessa camada superficial. O uso de altos teores de adições minerais no concreto influencia significativamente a resistência da camada de cobrimento ao ataque químico e a estrutura dos poros. Esta dissertação tem por objetivo analisar, através dos resultados obtidos nos ensaios de absorção capilar de água, conforme a norma RILEM TC-116 PCD, e de difusão de água, realizado seguindo as diretrizes de Dan et al (1988), apresentadas por Isaia (1995), baseadas em publicações de CSTB, a percolação de água na camada de cobrimento do concreto, além de correlacionar com a resistência a 50 MPa , o volume total de mercúrio intrudido e o diâmetro crítico dos poros. Para realização dessas análises, foram moldadas peças protótipos de 75 cm x 20 cm x 15 cm, que permaneceram em exposição ambiental até a data de realização dos ensaios. Os protótipos foram moldados com altos teores de escória, 70% e cinza volante 20%, em substituição à massa de cimento, com e sem adição de 20% de cal hidratada, em massa, e uma relação a/mc 0,3, 0,4, 0,5, além do traço de referência, somente com cimento e relação a/c 0,4; 0,6 e 0,8. Os ensaios de absorção capilar e de difusão de água foram realizados aos 91 e 300 dias. Para executar o estudo comparativo entre essas duas idades, foram extraídos testemunhos 10 cm x 20 cm dos protótipos sendo cerrados a 0, 2,5 e 5,0 cm de profundidade a partir da superfície. Após a realização das análises, observou-se que a substituição de cimento por adições minerais acarreta uma diminuição na resistência à compressão, sendo mais acentuada nas idades iniciais e amenizada com o passar do tempo. Em relação aos coeficientes de absorção e de difusão de água dos concretos com adições minerais, comparados com os concretos de referência, em igualdade de a/mc e idades analisadas, o uso de adições resultou em significativas reduções nesses coeficientes, que chegam a 79% na absorção e de 69% na difusão, aos 300 dias. Quando analisados em função da profundidade (em igualdade de a/mc), as reduções da camada 3 em relação à camada 1 chegam a 55% na absorção e 31% na difusão, aos 300 dias e nos traços com adição de cal hidratada. Esse comportamento é justificável pelo fato de a cal hidratada armazenar água auxiliando nos processos de hidratação, produzindo uma matriz mais compacta. Em igualdade de resistência, as reduções são de 86% para a absorção e de 70% para a difusão. Observa-se, tanto para a absorção como para a difusão, uma forte correlação com o volume total intrudido e o diâmetro dos poros aos 300 dias.

The carbonation phenomenon, reaction between CO2 from the atmosphere in the presence of humidity with the Portland cement hydration products, induces pH reduction to levels that can cause the elimination of steel s protective layer, enabling the corrosion mechanism of the steel structure to start.. This is one of the main pathologies in the reinforced concrete and its occurrence depends on the existence of oxygen, humidity and potential difference between two different locations of the steel bar. This research analyzed the performance of different concrete mixtures produced with Portland cement with high levels of blast furnace slag, with and without the chemical activator sodium sulfate (Na2SO4), in relation to compressive strength, capillary absorption and carbonation. For comparison purposes, gray Portland cement concrete test samples were also cast. For the white Portland cement concrete, slag contents of 0% and 50%, without and with chemical activator at concentrations of 4% and 70% were chosen. With the gray Portland cement it was produced concrete with 0% and 50% of slag addition, with and without chemical activator. For each mixture was adopted water/binder ratios of 0.30, 0.42 and 0.55. The samples cast with white Portland cement, destined to the compressive strength tests were broken at 3, 7, 28 and 91 days and the capillary absorption tests were done 91 days after molding. The samples destined to accelerated carbonation tests, cast with the two kinds of cements, were submitted to an atmosphere with 2% CO2 concentration, temperature of 23±1ºC and relative humidity of 75±2%. The carbonation depths determination was realized in the ages of 0, 3, 6, 9 and 12 weeks, after entrance in the chamber. From results obtained it was noticed that compressive strength reduced as the slag content and water/binder ration increased. In more advanced ages, however, the difference in compressive strength between mixtures with slag and the reference mixture was smaller than in the first ages. The capillary absorption reduced with the slag content increase, as a consequence of the refinement pores. The carbonation depth, for the white and gray concretes, increased with the slag content and the chemical activator utilization. In a comparison between white and gray Portland cement concretes, for the same slag content and water/binder ratio, the higher carbonation depths were reached with the white concrete, and this difference was higher when the water/binder ratio was increased. / O fenômeno da carbonatação, reação entre o CO2 da atmosfera em presença de umidade com os produtos de hidratação do cimento Portland, provoca a redução do pH do concreto a níveis que podem causar a eliminação da película passivadora do aço, podendo ocorrer a instalação do mecanismo de corrosão das armaduras, uma das principais patologias em estruturas de concreto armado, desde que para isto, exista oxigênio, umidade e uma diferença de potencial entre dois pontos distintos da barra de aço. Esta pesquisa analisou o desempenho de diferentes misturas de concretos produzidos com cimento Portland branco com altos teores de escória de alto forno, com e sem ativador químico sulfato de sódio (Na2SO4), frente à resistência à compressão, absorção capilar e carbonatação. Para efeito de comparação da resistência à carbonatação, também foram moldadas amostras com concreto de cimento Portland cinza. Para o concreto de cimento Portland branco foram adotados os teores de adição de escória de 0%, 50% sem e com ativador químico no teor de 4% e 70%. Com o cimento Portland cinza foram produzidos concretos com 0% e 50% de adição de escória sem e com ativador químico. Para cada mistura foram adotadas três relações água/aglomerante, 0,30, 0,42 e 0,55. Os corpos-deprova, moldados com cimento Portland branco, destinados aos ensaios de resistência à compressão foram rompidos aos 3, 7, 28 e 91 dias e os ensaios de absorção capilar foram realizados 91 dias após a moldagem. As amostras destinadas ao ensaio de carbonatação acelerada, moldadas com os dois tipos de cimento, foram submetidas a uma atmosfera com concentração de 2% de CO2, temperatura de 23±1ºC e umidade relativa de 75±2%. A determinação da profundidade carbonatada foi realizada nas idades de 0, 3, 6, 9 e 12 semanas, após a entrada na câmara de carbonatação. Dos resultados obtidos constatou-se redução nos valores de resistência à compressão das misturas com escória com o aumento no teor de adição e da relação água/aglomerante, porém, em idades mais avançadas, a diferença entre as resistências das misturas com adição e aquelas da mistura de referência foi menor que nas primeiras idades. A absorção capilar diminuiu com o aumento no teor de adição de escória, conseqüência do refinamento dos poros. A profundidade de carbonatação, para os concretos branco e cinza, aumentou com o aumento no teor de escória e a utilização de ativador químico. Na comparação entre os concretos de cimento Portland branco e cinza analisados, para mesmo teor de adição e relação água/aglomerante, as maiores profundidades de carbonatação foram atingidas pelo concreto branco, e esta diferença foi maior à medida que aumentou a relação água/aglomerante.

Drying Shrinkage is a phenomenon that occurs in concrete, subjected or not to a load, due to water loss, once exposed to environment and allowed to dry. It is responsible for almost the entire total shrinkage strain in concrete. A concrete element with restrained shrinkage deformation may develop tensions that cause cracks, allowing the ingress of aggressive agents that may cause some damage to the reinforcement, reducing, consequently, its strength and durability. The most common aggressive agent into concrete is the chloride ion, which is considered the great responsible for the early reinforcement corrosion of concrete structures, affecting its stability and durability. Corrosion of reinforcement bars due to the ingress of salts from sea water into concrete is recognized to be the most influent factor in the destructive mechanisms for marine structures. The use of mineral admixtures such as blast furnace slag, the increase of curing duration and the water/binder ratio reduction are measures that may reduce the chloride ion penetration. The aim of this study was to investigate the influence of the cement replacement content by slag, as well as the duration of curing on drying shrinkage, chloride ion penetration and compressive strength of concretes made with high early age strength cement and white Portland cement. Water-binder ratios of 0.30, 0.42 and 0.55, curing duration of 3 and 7 days, besides the cement replacement contents of 0%, 50% and 70% were investigated. In order to analyze the influence of the alkali activation on the properties investigated, a concrete made with 50% white Portland cement replacement content by slag and activated by sodium sulfate (4% in mass of binder) was used. The compressive strength was evaluated in the ages of 3, 7, 28 and 91 days; the drying shrinkage in the ages of 7, 14, 21, 28, 35, 56, 91 and 182 days, and the chloride ion penetration (immersion test in chloride solution) in the ages of 7, 14, 28, 56 and 91 days. Before being immersed in the chloride solution, the specimens were subjected to a drying period of 91 days. The results obtained revealed that an increase in the slag content decreased the compressive strength and the drying shrinkage values, besides the smaller depths of chloride penetration with both cements used. Reducing the curing duration resulted greater drying shrinkage and depth of chloride penetration for both cements, independently the slag content. / A retração hidráulica é um fenômeno que ocorre no concreto, submetido ou não a carregamento, devido à perda de umidade, uma vez exposto ao meio ambiente e permitida sua secagem. Ela é responsável por praticamente toda a deformação total por retração no concreto. Um elemento de concreto com restrição de deformação por retração pode desenvolver tensões que levam à formação de fissuras, através das quais agentes agressivos podem penetrar e causar algum dano à armadura, reduzindo sua resistência e durabilidade. O agente agressivo mais comum é o íon cloreto, o qual é considerado como a maior causa de corrosão prematura das barras de armaduras das estruturas de concreto, afetando sua estabilidade e vida útil. A corrosão de armaduras devido ao ingresso de íons cloretos da água do mar no concreto é universalmente conhecida como o fator de maior influência nos mecanismos destrutivos de estruturas marinhas. A utilização de adições minerais como a escória de alto forno, o aumento no prazo de cura e a redução na relação água/aglomerante são medidas que podem diminuir a penetração desses íons no concreto. Este trabalho teve por objetivo investigar a influência do teor de escória e do período de cura na retração hidráulica, na penetração de íons cloretos e na resistência à compressão axial de concretos compostos de cimento Portland de alta resistência inicial e cimento Portland branco estrutural. Foram adotadas relações água/aglomerante de 0.30, 0.42 e 0.55, teores de escória, em substituição ao cimento Portland, de 0%, 50% e 70%, além de períodos de cura de 3 e 7 dias. Foi empregada uma mistura composta de 50% de escória em substituição ao cimento Portland branco, ativada quimicamente por sulfato de sódio (4% da massa de aglomerante) para analisar a influência do ativador nas propriedades investigadas. As idades avaliadas para o ensaio de resistência à compressão foram de 3, 7, 28 e 91 dias; para retração hidráulica idades de 7, 14, 21, 28, 35, 56, 91 e 182 dias e, para penetração de íons cloretos (imersão em solução salina) as idades de 7, 14, 28, 56 e 91 dias. Antes de serem imersos em solução salina os corpos-de-prova foram submetidos a um período de secagem de 91 dias. Dos resultados obtidos, constatou-se que o aumento do teor de escória resultou em decréscimo nos valores de resistência à compressão, de retração e de penetração de cloretos para os dois cimentos investigados. A diminuição no período de cura resultou em maiores valores de retração e de penetração de cloretos, tanto no concreto branco quanto no cinza, independentemente do teor de escória utilizado.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Sulfate ions found in seawater, groundwater and wastewater are aggressive agents that can result in severe concrete degradation. They react with cement hydration products and depending on the associated cations present (magnesium, calcium, potassium, sodium, ammonium), their concentrations and the conditions of the environment, this can result in the formation of ettringite, gypsum or thaumasite, decalcification of C-S-H, processes which may cause expansion, cracking and loss of mass and strength.When high sulfate resistance is required, national and international standards prescribe the use of cement with high concentrations of granulated blast furnace slag (GBFS). By substituting GBFS for cement, lower amounts of clinker are required. In addition, the pozzolanic activity of GBFS takes up the CH released by the hydration of silicates (C3S e C2S), which then is not available to react with sulfate ions to form gypsum, resulting in a more dense paste with lower penetrability. GBFS is one of the few mineral admixtures that can be added to white Portland cement (WPC), a material with widespread usage in civil construction, particularly in cases where concrete is used as a finished surface for architectural impact. The substitution of GBFS for WPC offers technical and environmental gains as well as economic advantages due to the higher cost of WPC. This study investigated the sulfate resistance of WPC with 0%, 50% and 70% GBFS as a substitution for cement. A mix with 50% GBFS that was chemically activated with Na2SO4 (4% b/w of binder) was also studied. The performance of the blended cements was monitored by exposing the prepared mortar specimens to a solution of Na2SO4 (5%) for 2 years according to ASTM C1012/04 and using TG/DTA, DRX and SEM/EDX analyses of the paste samples. For comparison, the same blends prepared with high early strength Portland cement (PC) were also used. The results showed the benefits of the use of GBFS in both types of cement, with higher concentrations of slag resulting in improved sulfate resistance. The use of chemical activation reduced expansion when compared with mixtures without activation. For long-term exposure, all WPC blends showed lower expansion than the corresponding blends with PC. Microstructural analysis identified ettringite and gypsum as the main degradation products of the sulfate attack. / Os íons sulfato, encontrados na água do mar, em águas subterrâneas e em águas residuárias são agentes agressivos que podem levar a uma severa degradação do concreto. Ao reagirem com os produtos de hidratação do cimento, dependendo do tipo de cátion a que estão associados (magnésio, cálcio, potássio, sódio, amônio, etc.), da concentração e das condições do meio, podem levar à formação de etringita secundária, sulfato de cálcio, taumasita, descalcificação do C-S-H, podendo ocorrer expansão, fissuração, perda de massa e de resistência. Quando se faz necessário assegurar uma elevada resistência ao sulfato, a normalização nacional e internacional, dentre outras recomendações, especifica o uso de cimento com elevados teores de escória de alto-forno. Além da redução da quantidade de clínquer ocasionada pela substituição do cimento por escória, a atividade pozolânica da mesma consome o CH liberado pela hidratação dos silicatos (C3S e C2S), que não fica disponível para reagir com os sulfatos e formar sulfato de cálcio, e promove a densificação da matriz, reduzindo a penetrabilidade do meio. A escória é também uma das poucas adições que podem ser incorporadas no cimento Portand branco (CPB), que vem se tornando uma nova tendência dentro do contexto da construção civil, quando se opta por concreto aparente em obras com forte apelo arquitetônico. Além das vantagens técnicas e ambientais, a substituição do cimento branco por escória possibilita a redução do custo bastante elevado do CPB. Neste estudo, investigou-se a resistência ao sulfato de sódio do CPB com teores de substituição de escória de alto-forno de 0%, 50% e 70%. Também foi investigada uma mistura com 50% de escória ativada quimicamente por Na2SO4 (em teor de 4% em massa do material aglomerante). O desempenho dos cimentos foi avaliado pela exposição de argamassas em solução de 5% de Na2SO4 por dois anos, de acordo com a ASTM C1012/04 e através de análise de DRX, TG/DTA e MEV/EDS em pastas. Para comparação foram investigadas as mesmas misturas compostas com cimento Portland de alta resistência inicial, CPV-ARI. Os resultados mostraram os benefícios do uso da escória em ambos os cimentos, sendo que o acréscimo do seu teor aumentou a resistência ao ataque por sulfatos. A ativação química reduziu a expansão comparativamente às misturas sem ativador. A longo prazo, todas as misturas com o CPB apresentaram menor expansão do que aquelas com CPV-ARI. A análise da microestrutura identificou a etringita e o sulfato de cálcio como os principais produtos de degradação por sulfato de sódio.