<p>Hydrated portland cement provides the solid adhesive matrix necessary to bind aggregate (sand and gravel) into concrete. The hydration reaction requires water, however the products of the reaction limit further diffusion of water to unreacted cement. Superabsorbent polymer (SAP) hydrogel particles absorb mixing water, then subsequently desorb when the relative humidity drops, serving as internal water reservoirs within the cement matrix to shorten diffusion distances and promote the hydration reaction in a process called internal curing. Internally cured cementitious mixtures exhibit an increased degree of hydration and reduced shrinkage and cracking, which can increase concrete service life. Increased service life can, in turn, reduce overall demand for portland cement production, thereby lowering CO2 emissions.</p> <p>This dissertation addresses practical implementation questions key to the translation of SAP hydrogel internal curing technology to from the benchtop to the field in transportation applications, including: (1) What effects do mix design adjustments made to increase mixture flow when using SAP have on cementitious mixture properties? and (2) What effect do cementitious binder characteristics have on SAP performance?</p> <p>The addition of SAP to a cementitious mixture changes the mixture’s flow behavior. Flow behavior is an important aspect of concrete workability and sufficient flow is necessary to place well consolidated and molded samples. Often, additional water is added to mixtures using SAP to account for the absorbed water, however cementitious mixture workability is often tuned using high range water reducing admixtures (e.g., polycarboxylate ester-based dispersants). Fresh and hardened properties of mortars were characterized with respect to flow modification method (using the mortar flow table test; compressive strength at 3, 7, and 28 days; flexural strength at 7 and 28 days; and microstructural characterization of 28-day mortars). At typical doses, it was found that the addition of extra water lowers the resulting compressive and flexural strength, while high range water reducing admixtures administered at doses to achieve sufficient mortar flow did not compromise compressive or flexural strength.</p> <p>The SAPs used in cement are generally poly(acrylamide-acrylic acid) hydrogels and are not chemically inert in high ionic-load environments, such as cement mixtures. The behavior of an industrial SAP formulation with characterized across five different cement binder compositions with respect the cement hydration reaction (using isothermal calorimetry, thermogravimetric analysis of hydration product fraction, and scanning electron microscopy (SEM)/energy dispersive x-ray spectroscopy (EDS) microstructural analysis), the absorption behavior of the SAP, and the fresh and hardened properties of SAP-cement composites (mortar flow and compressive and flexural strength). The change in properties induced by the addition of SAP was similar across ASTM Type I cements from three manufacturing sources, suggesting that SAP internal curing can be implemented predictably over time and geography. Excitingly, in analysis of cement systems meeting different ASTM standards (Type III and Type I with 30% replacement by mass with ground blast furnace slag), synergistic and mitigating reaction behaviors were observed, respectively, in Type III and slag cement, suggesting that further study of SAP with these cement systems could be of particular interest.</p>

A reação química que ocorre entre os hidróxidos alcalinos presentes nos poros do concreto e alguns minerais constituintes dos agregados tem causado sérios danos às estruturas. Até o presente momento a prevenção é a melhor forma de evitar que a reação se desencadeie, uma vez que as soluções remediativas ainda necessitam de estudos mais aprofundados para serem implementadas. Neste sentido, a utilização de adições pozolânicas no concreto tem se mostrado uma alternativa eficaz, sendo que a forma mais fácil de empregá-las é através do uso de cimentos compostos com adições. Porém, são poucos os estudos encontrados avaliando a capacidade desses cimentos na prevenção da reação. No Brasil, além dessa lacuna de conhecimento, faltam informações sobre a reatividade dos agregados utilizados no concreto. Então, o presente estudo avaliou a reatividade dos agregados mais utilizados para confecção de concreto nos estados do Paraná, Santa Catarina e Rio Grande do Sul frente à utilização de quatro tipos de cimento: CP V-ARI, CP V-ARI RS, CP IV e CP II-Z. Os métodos utilizados para essa avaliação foram a análise petrográfica, o ensaio acelerado das barras de argamassa, a microscopia eletrônica de varredura e a espectometria por dispersão de energia. Os resultados da análise petrográfica mostraram que todos os 40 agregados coletados possuem minerais reativos. As expansões medidas no ensaio acelerado acabaram por confirmar a potencialidade reativa desses minerais, pois todas as amostras moldadas com o CP V-ARI, o CP V-ARI RS e o CP II-Z foram classificadas como reativas ou potencialmente reativas, isto é, somente o CP IV foi eficaz para inibir as expansões deletérias. Por outro lado, as análises microscópicas mostraram que mesmo nos prismas menos expansivos houve a formação do gel sílico-alcalino, porém este ficou incluso nos poros da argamassa. Outra conclusão percebida foi a de que as maiores expansões ocorreram com os agregados de origem ígnea vulcânica, principalmente com os basaltos, que além de serem constituídos por minerais muito finos, apresentam em sua matriz mesóstases silicosas amorfas, também conhecidas como vidro vulcânico. / The chemical reaction that occurs between alkali hydroxides contained in concrete pores and some minerals contained in aggregates has been causing serious hazards to concrete structures. So far, prevention is the best way to avoid the occurrence of this reaction, once the solutions to repair the damage still need deeper researches to be implemented. Therefore, the use of Portland cements containing pozzolanic admixtures to produce has been an effective alternative. But there are few researches on the capability of those prevent reaction to occur. In Brazil, besides the lack of knowledge, there is little information about the reactivity of the aggregates applied in concrete production. So this research aimed to evaluate the reactivity of the most used aggregate to produce concrete in the states of Parana, Santa Catarina, and Rio Grande do Sul by testing four different types of cements as described: CP V-ARI, CP V-ARI RS, CP IV and CP II-Z. The methods applied to carry out this evaluation were the petrography analysis, the accelerated mortar bar test, scanning electron microscopy, and the dispersive energy spectrometry. The results obtained showed that all the forty aggregate samples collected have reactive minerals in their composition. The measured expansions during the accelerated test confirmed the reactive potentiality of these minerals, because all samples obtained from the CP V-ARI, CP V-ARI RS, and CP IV were classified as being reactive or potentially reactive, which means that CP IV was the only one capable of inhibit the hazardous expansion. On the other hand, the microscopic analyses showed, even in the less expansive prisms, that the formation of silica-alkaline gel has occurred, but this gel has remained in the pores of the mortar. Another conclusion of this research was that larger expansions occurred with the aggregates from volcanic igneous origin, especially basalts that, besides contained very fine minerals, presented in its matrix amorphous silica, also known as volcanic glass.

A reação química que ocorre entre os hidróxidos alcalinos presentes nos poros do concreto e alguns minerais constituintes dos agregados tem causado sérios danos às estruturas. Até o presente momento a prevenção é a melhor forma de evitar que a reação se desencadeie, uma vez que as soluções remediativas ainda necessitam de estudos mais aprofundados para serem implementadas. Neste sentido, a utilização de adições pozolânicas no concreto tem se mostrado uma alternativa eficaz, sendo que a forma mais fácil de empregá-las é através do uso de cimentos compostos com adições. Porém, são poucos os estudos encontrados avaliando a capacidade desses cimentos na prevenção da reação. No Brasil, além dessa lacuna de conhecimento, faltam informações sobre a reatividade dos agregados utilizados no concreto. Então, o presente estudo avaliou a reatividade dos agregados mais utilizados para confecção de concreto nos estados do Paraná, Santa Catarina e Rio Grande do Sul frente à utilização de quatro tipos de cimento: CP V-ARI, CP V-ARI RS, CP IV e CP II-Z. Os métodos utilizados para essa avaliação foram a análise petrográfica, o ensaio acelerado das barras de argamassa, a microscopia eletrônica de varredura e a espectometria por dispersão de energia. Os resultados da análise petrográfica mostraram que todos os 40 agregados coletados possuem minerais reativos. As expansões medidas no ensaio acelerado acabaram por confirmar a potencialidade reativa desses minerais, pois todas as amostras moldadas com o CP V-ARI, o CP V-ARI RS e o CP II-Z foram classificadas como reativas ou potencialmente reativas, isto é, somente o CP IV foi eficaz para inibir as expansões deletérias. Por outro lado, as análises microscópicas mostraram que mesmo nos prismas menos expansivos houve a formação do gel sílico-alcalino, porém este ficou incluso nos poros da argamassa. Outra conclusão percebida foi a de que as maiores expansões ocorreram com os agregados de origem ígnea vulcânica, principalmente com os basaltos, que além de serem constituídos por minerais muito finos, apresentam em sua matriz mesóstases silicosas amorfas, também conhecidas como vidro vulcânico. / The chemical reaction that occurs between alkali hydroxides contained in concrete pores and some minerals contained in aggregates has been causing serious hazards to concrete structures. So far, prevention is the best way to avoid the occurrence of this reaction, once the solutions to repair the damage still need deeper researches to be implemented. Therefore, the use of Portland cements containing pozzolanic admixtures to produce has been an effective alternative. But there are few researches on the capability of those prevent reaction to occur. In Brazil, besides the lack of knowledge, there is little information about the reactivity of the aggregates applied in concrete production. So this research aimed to evaluate the reactivity of the most used aggregate to produce concrete in the states of Parana, Santa Catarina, and Rio Grande do Sul by testing four different types of cements as described: CP V-ARI, CP V-ARI RS, CP IV and CP II-Z. The methods applied to carry out this evaluation were the petrography analysis, the accelerated mortar bar test, scanning electron microscopy, and the dispersive energy spectrometry. The results obtained showed that all the forty aggregate samples collected have reactive minerals in their composition. The measured expansions during the accelerated test confirmed the reactive potentiality of these minerals, because all samples obtained from the CP V-ARI, CP V-ARI RS, and CP IV were classified as being reactive or potentially reactive, which means that CP IV was the only one capable of inhibit the hazardous expansion. On the other hand, the microscopic analyses showed, even in the less expansive prisms, that the formation of silica-alkaline gel has occurred, but this gel has remained in the pores of the mortar. Another conclusion of this research was that larger expansions occurred with the aggregates from volcanic igneous origin, especially basalts that, besides contained very fine minerals, presented in its matrix amorphous silica, also known as volcanic glass.

A reação química que ocorre entre os hidróxidos alcalinos presentes nos poros do concreto e alguns minerais constituintes dos agregados tem causado sérios danos às estruturas. Até o presente momento a prevenção é a melhor forma de evitar que a reação se desencadeie, uma vez que as soluções remediativas ainda necessitam de estudos mais aprofundados para serem implementadas. Neste sentido, a utilização de adições pozolânicas no concreto tem se mostrado uma alternativa eficaz, sendo que a forma mais fácil de empregá-las é através do uso de cimentos compostos com adições. Porém, são poucos os estudos encontrados avaliando a capacidade desses cimentos na prevenção da reação. No Brasil, além dessa lacuna de conhecimento, faltam informações sobre a reatividade dos agregados utilizados no concreto. Então, o presente estudo avaliou a reatividade dos agregados mais utilizados para confecção de concreto nos estados do Paraná, Santa Catarina e Rio Grande do Sul frente à utilização de quatro tipos de cimento: CP V-ARI, CP V-ARI RS, CP IV e CP II-Z. Os métodos utilizados para essa avaliação foram a análise petrográfica, o ensaio acelerado das barras de argamassa, a microscopia eletrônica de varredura e a espectometria por dispersão de energia. Os resultados da análise petrográfica mostraram que todos os 40 agregados coletados possuem minerais reativos. As expansões medidas no ensaio acelerado acabaram por confirmar a potencialidade reativa desses minerais, pois todas as amostras moldadas com o CP V-ARI, o CP V-ARI RS e o CP II-Z foram classificadas como reativas ou potencialmente reativas, isto é, somente o CP IV foi eficaz para inibir as expansões deletérias. Por outro lado, as análises microscópicas mostraram que mesmo nos prismas menos expansivos houve a formação do gel sílico-alcalino, porém este ficou incluso nos poros da argamassa. Outra conclusão percebida foi a de que as maiores expansões ocorreram com os agregados de origem ígnea vulcânica, principalmente com os basaltos, que além de serem constituídos por minerais muito finos, apresentam em sua matriz mesóstases silicosas amorfas, também conhecidas como vidro vulcânico. / The chemical reaction that occurs between alkali hydroxides contained in concrete pores and some minerals contained in aggregates has been causing serious hazards to concrete structures. So far, prevention is the best way to avoid the occurrence of this reaction, once the solutions to repair the damage still need deeper researches to be implemented. Therefore, the use of Portland cements containing pozzolanic admixtures to produce has been an effective alternative. But there are few researches on the capability of those prevent reaction to occur. In Brazil, besides the lack of knowledge, there is little information about the reactivity of the aggregates applied in concrete production. So this research aimed to evaluate the reactivity of the most used aggregate to produce concrete in the states of Parana, Santa Catarina, and Rio Grande do Sul by testing four different types of cements as described: CP V-ARI, CP V-ARI RS, CP IV and CP II-Z. The methods applied to carry out this evaluation were the petrography analysis, the accelerated mortar bar test, scanning electron microscopy, and the dispersive energy spectrometry. The results obtained showed that all the forty aggregate samples collected have reactive minerals in their composition. The measured expansions during the accelerated test confirmed the reactive potentiality of these minerals, because all samples obtained from the CP V-ARI, CP V-ARI RS, and CP IV were classified as being reactive or potentially reactive, which means that CP IV was the only one capable of inhibit the hazardous expansion. On the other hand, the microscopic analyses showed, even in the less expansive prisms, that the formation of silica-alkaline gel has occurred, but this gel has remained in the pores of the mortar. Another conclusion of this research was that larger expansions occurred with the aggregates from volcanic igneous origin, especially basalts that, besides contained very fine minerals, presented in its matrix amorphous silica, also known as volcanic glass.

En el siguiente informe de tesis, se presenta el desarrollo de un concreto especial reforzado con fibra de basalto para evitar la corrosión en los elementos estructurales encontrados en la ciudad de Pisco. Este material es clasificado como polímero utilizado para mejorar las propiedades físicas y mecánicas del concreto. Por ello, los ensayos en probetas estándar de concreto con diferentes porcentajes de este adicionado generan resultados eficientes que comprueban la hipótesis a investigar. Como punto de referencia y comparación también se evaluó un concreto convencional. En ambos casos fueron sometidos a los ensayos de compresión y tracción para medir su resistencia. Además, se realizaron ensayos para medir su durabilidad tales como álcali-sílice y carbonatación. Los resultados generan beneficios en la actividad de la construcción y minimizan los costos económicos surgidos por la pérdida de materiales generado por la corrosión. / The following thesis report presents the development of a special concrete reinforced with basalt fiber to prevent corrosion in the structural elements found in the city of Pisco. This material is classified as a polymer used to improve the physical and mechanical properties of concrete. Therefore, the tests in standard concrete specimens with different percentages of this additive generate efficient results that prove the hypothesis to be investigated. As a point of reference and comparison, a conventional concrete was also evaluated. In both cases they were subjected to compression and traction tests to measure their resistance. In addition, tests were carried out to measure its durability such as alkali-silica and carbonation. The results generate benefits in the construction activity and minimize the economic costs arising from the loss of materials generated by corrosion. / Tesis