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Denise Dal Molin     Institute, Department or Faculty Head 
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Denise Dal Molin published an article in November 2018.
Top co-authors See all
José Luis Duarte Ribeiro

125 shared publications

Universidade Federal do Rio Grande do Sul, Brasil

Paulo J. M. Monteiro

70 shared publications

Department of Civil and Environmental Engineering, University of California, Berkeley, California United States

Ana Paula Kirchheim

22 shared publications

Universidade Federal do Rio Grande do Sul, Brasil

Angela Borges Masuero

19 shared publications

Universidade Federal do Rio Grande do Sul, Brasil

G. L. Vieira

10 shared publications

Universidade Federal do Espirito Santo, Brazil

21
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Distribution of Articles published per year 
(2008 - 2018)
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8
 
Publications See all
Article 0 Reads 0 Citations Influence of preloading-induced microcracking on the durability of concrete produced with different types of cement Simone Venquiaruto, Lucília Bernardino Da Silva, Denise C.C.... Published: 01 November 2018
Construction and Building Materials, doi: 10.1016/j.conbuildmat.2018.08.057
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Article 0 Reads 1 Citation Influence of the Quartz Deformation Structures for the Occurrence of the Alkali–Silica Reaction Francieli Tiecher, Renata N. Florindo, Geilma L. Vieira, Már... Published: 12 September 2018
Materials, doi: 10.3390/ma11091692
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Defects in the crystalline structure of quartz facilitate the connection with the alkali hydroxides, since under a high alkalinity condition (e.g., in concrete), the Si-O bonds of quartz are easily broken. This study set out to investigate the influence of the deformation structures of quartz on its susceptibility to the alkali–silica reaction. A granite, a protomylonite, and a mylonite were selected for this study. Using optical microscopy, the quartz grains contained in these rocks were quantified and their texture characterized. The quartz samples extracted from the rocks were analyzed by magnetic nuclear resonance, to evaluate their potential for dissolving silica as well as changes in their atomic scale before and after the reaction with alkali hydroxides. These analyses were compared with the results of the accelerated mortar bar test. The study showed that the quartz with intense undulatory extinction and deformation bands denotes the most favorable condition to the development of the alkali–silica reaction. However, on an atomic scale, the slightly deformed grains were highly prone to react. Thus, in a high alkalinity condition, over a long period of time, any quartz tends to develop the alkali–silica reaction, regardless of the deformation degree of the grain.
Article 0 Reads 0 Citations Effect of Gypsum on the Early Hydration of Cubic and Na-Doped Orthorhombic Tricalcium Aluminate Ana Kirchheim, Erich Rodríguez, Rupert Myers, Luciano A. Gob... Published: 07 April 2018
Materials, doi: 10.3390/ma11040568
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The tricalcium aluminate (C3A) and sulfate content in cement influence the hydration chemistry, setting time and rheology of cement paste, mortar and concrete. Here, in situ experiments are performed to better understand the effect of gypsum on the early hydration of cubic (cub-)C3A and Na-doped orthorhombic (orth-)C3A. The isothermal calorimetry data show that the solid-phase assemblage produced by the hydration of C3A is greatly modified as a function of its crystal structure type and gypsum content, the latter of which induces non-linear changes in the heat release rate. These data are consistent with the in situ X-ray diffraction results, which show that a higher gypsum content accelerates the consumption of orth-C3A and the subsequent precipitation of ettringite, which is contrary to the cub-C3A system where gypsum retarded the hydration rate. These in situ results provide new insight into the relationship between the chemistry and early-age properties of cub- and orth-C3A hydration and corroborate the reported ex situ findings of these systems.
Article 0 Reads 1 Citation Relationship between Degree of Deformation in Quartz and Silica Dissolution for the Development of Alkali-Silica Reactio... Francieli Tiecher, Marcia E. B. Gomes, Denise C. C. Dal Moli... Published: 04 September 2017
Materials, doi: 10.3390/ma10091022
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This paper presents research on the influence of quartz deformation in aggregates for the development of the alkali-silica reaction in concrete and its relationship with silica dissolution. The study also compares these characteristics with the field behavior of such rocks in concrete. The paper proposes parameters to classify the different degrees of deformation of quartz. Transmission electron microscopy showed the presence of walls even in slightly deformed quartz, which indicate the presence of the internal paths available to react with the alkaline concrete pore solutions and point to the potential development of an alkali-silica reaction. The presence of the deformation bands in the quartz grains leads to the alkali aggregate reaction occurring more rapidly. The visible spectrophotometer test was performed to evaluate the dissolution potential of the different samples of deformed quartz, which confirmed that the reactivity of the quartz increases as the deformation of the crystalline structure increases. The parameters established in the present study could be verified by analyzing the behavior of reactive and innocuous aggregates from the buildings.
Article 0 Reads 1 Citation Effect of the incorporation of aggregates with high sulfide content on the mechanical and microstructural properties of ... Maria De Jesus Gomides, Denise Coitinho Carpena Dal Molin, J... Published: 10 August 2017
Matéria (Rio de Janeiro), doi: 10.1590/s1517-707620170003.0185
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The mineralogical change in the sulfides present in many aggregates can affect their stability, which may undermine the performance of the concrete. This is a complex process and there is limited research in this area. In this study, we examined the influence of aggregates containing a high sulfide content on the performance of concrete containing slag cement. The sulfides present in the aggregates were initially identified and quantified. The changes at the microstructural level of the concrete caused by the sulfide-containing aggregates were then examined. These included volume changes, as well as their effect on the compressive strength and modulus of elasticity. The results show that slag cement does not reduce expansion, and it is this expansion that affects the mechanical properties of concrete. Keywords: sulfide; oxidation; expansion; strength; concrete
Article 0 Reads 0 Citations Avaliação de processos de misturas de concretos com agregados graúdos reciclados Luciana De Nazaré Pinheiro Cordeiro, Paulo Sérgio Lima Souza... Published: 01 July 2017
Ambiente Construído, doi: 10.1590/s1678-86212017000300174
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Resumo A reutilização dos resíduos de construção civil vem sendo uma estratégia do setor para alcançar a sustentabilidade, mesmo sendo aplicada em um pequeno volume de obras. A variabilidade do resíduo de concreto é uma condição inerente do produto, que precisa ser levada em consideração, e o controle do processo produtivo de concretos produzidos com resíduos de concreto pode ser uma maneira de majorar a qualidade do compósito final. Nesse sentido, este artigo tem por objetivo avaliar a eficiência do processo de mistura e do tipo de misturador ante a fragilidade do desempenho de concretos com agregados graúdos reciclados de concreto e verificar a influência na resistência à compressão. Como objetivo específico tem-se o efeito do misturador no desempenho do concreto. O agregado graúdo reciclado de concreto foi usado em substituição total ao agregado graúdo natural. E os resultados mostraram que não há diferença significativa entre os concretos produzidos a partir de diferentes ordens de misturas; ambas promoveram resultados satisfatórios de resistência à compressão na idade de 28 dias. Porém, as misturas realizadas em misturador de eixo vertical se mostraram mais eficientes que as misturas produzidas em betoneiras de eixo inclinado, uma vez que os concretos produzidos pelas primeiras se mostram com menor coeficiente de variação. Acredita-se que as características do equipamento contribuíram para uma melhor homogeneidade, levando à menor variabilidade nos resultados do concreto. Abstract The reuse of construction waste is a strategy employed to achieve sustainability, however, only a small number of construction initiatives use it. The variability of concrete residue is an inherent condition of this product and it must be considered. The control of the production process of concrete produced with concrete waste can improve the quality of the final composite. This paper aims to evaluate the effect of the mixing process and the mixer type on the fragility of recycled coarse aggregate concrete and to investigate their influence on compressive strength. This study also evaluates the effect of the mixer on concrete performance. Recycled coarse aggregate concrete was used as a total replacement for natural coarse aggregate. The results showed no significant differences between concrete produced from different types of mixtures, however, both yielded satisfactory compressive strength results at 28 days. However, the mixtures made in the vertical shaft mixer were more efficient than the mixtures produced in the inclined axis mixer, as the concrete produced by the former presented a lower variation coefficient. The study concluded that the equipment's characteristics contributed to better uniformity, leading to less variability in the resulting concrete.
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