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![Distribuição granulométrica dos materiais finos usados na pesquisa. [Figure 3: Particle size distribution of the fine materials used in this research.]](profile/Victor-Pandolfelli/publication/262709810/figure/fig1/AS:392391044419588@1470564723539/Figura-3-Distribuicao-granulometrica-dos-materiais-finos-usados-na-pesquisa-Figure-3.png)
Distribuição granulométrica dos materiais finos usados na pesquisa. [Figure 3: Particle size distribution of the fine materials used in this research.]
Source publication
The search for materials with better mechanical performance and durability has been the aim of the concrete's technology researchers. In order to attain this target, concretes developed with engineering microstructure are necessary. Based on the concepts of particle packing and dispersion, it is possible to obtain materials with dense matrix and ap...
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Citations
... The grinding process using the ball mill after 14,000 cycles proved to be adequate, allowing a greater use of the material to make structural mortars. Studies have shown that for a same water/cement ratio, reducing the average particle size generally results in a higher hydration rate and thus better properties and higher strengths at the early ages (Castro, Liborio, & Pandolfelli, 2009). The difficulty in grinding this material may be associated with the mineralogical composition of IOT, which contains high hardness minerals, such as hematite, quartz, goethite and magnetite. ...
This study discusses and analyzes an alternative of IOT reuse as addition in structural mortars, evaluating the influence of IOT addition contents. The material was physically and chemically characterized. Structural mortars were molded with 10%, 20%, 30% and 40% of addition of IOT in relation to cement mass. We investigate physical properties, mechanical indicators, durability indicators and microstructure. The tailings are composed of predominantly quartz, hematite and goethite, and no components were found that could compromise the cementitious composites. The addition of IOT provided a tendency to reduce open porosity. The addition of 30% IOT was the most efficient in closing pores. All addition contents led to the maintenance or gains in mechanical properties, and a 10% gain in flexural tensile strength was observed for the addition of 10% IOT. The addition of 40% IOT promoted a 14% gain in compressive strength and maintenance of flexural tensile strength. This addition content evidences that the carbonation depth was not significantly affected. Based on the results, the addition percentages of 30-40% are interesting as to the analyzed properties.
When a concrete is produced, especially a high performance one, the first concern is the cement type to be used, making this binder an essential compound. The rheological properties of high performance concretes are related to the hydration of cement aluminates phase, whereas the development of mechanical strength depends on the hydrated silicates formed. Thus, variations on cement characteristics influence the properties of a concrete, being observed different behaviors for mixtures produced with distinct cements. The present paper aims to evaluate the influence of cement type on the performance of special concretes designed using computing techniques. The fresh properties were evaluated measuring the fluidity index and the rheological behavior of the material. In the hardened condition, the mechanical strength were evaluated by the compressive, splitting tensile and 3 point bending tests, whereas the Young's modulus was measured by the static and dynamic methods. By comparing all the measured properties, the concretes produced with Portland cement showed better performance than that containing calcium aluminate cement, being the high early strength Portland cement more efficient than the slag-modified Portland cement for the production of high performance mixtures and until the age of 28 days.
