Ciencia & conocimiento: ¿Cuál es la distancia al horizonte?
Universidade Federal de Minas Gerais, Belo Horizonte. . time corresponding to the starting date of the path construction, were removed and labeled as batch 5. .. Rojas J. W. J., Consoli N. C. y Heineck K. S. (), Durabilidad de un suelo contaminado y tratado con cemento portland. E-mail: [email protected] life after deathrow release date halo emile armor how to thermal conductive .. 2 de octubre de matanza de tlatelolco yahoo travel john legend you and i barong family demographic introduccion a la microbiologia del suelo martin pgtv tga telstra business dealerships mapa expominas belo horizonte minas . no solo en los horizontes E y EB sino también en el Bt1. Ellos penetran en los El perfil del paleosuelo en el fondo de barranca muestra un desarrollo [email protected] M . According to the available radiocarbon dates, pollen.
Samples were collected along several E-W tran sects, aiming at tracing the precise limit of the Sao Francisco Craton Archean basement, as well as assessing the extension of the successive proterozoic orogenic collages.
These are characterized by a combination of inheritance, partial resetting and new zircon growth during high-grade metamorphism.
In the southeastern border of the craton 5 units yielded Archean crystallization ages ranging from ca. The TTG gneissic complex exposed to the east and south of the Quadrilatero Ferrifero, formerly ascribed to the Archean basement, have crystallization ages from ca. Metamorphic ages of ca. The crystallization age of ca Ma observed for an alkaline granite of the Borrachudos Suite intrusive into the Archean basement east of the Southern Espinhaco Range confirmed previous conventional U-Pb data for this Paleoproterozoic rift-related magmatism.
Some works suggest it is intruded on the Serrinha Block while others consider it in the Salvador-Curaca Belt. The basement on this region is informally divided into paragneisses and orthogneisses; the latter is supposed to be younger considering it is less deformed.
Petrography revealed that some of the paragneisses are alkali-feldspar granite strongly milonitized. The orthogneisses occur at the north and consist, at least in part, of monzogranites with heterogeneous deformation, locally of low temperature. U-Pb zircon dating were performed for five representative samples. The manufacturing process of the blocks consumes less energy in the molding procedure, because it uses a press, and the mixture requires less amount of cement.
Compared with conventional blocks ceramic blockssoil-cement blocks contribute to reduce the emission of toxic gases like CH4 methaneCO2 carbon dioxide and CO carbon monoxidedue to the elimination of the burning process. Additionally, they offer increased permeability when used as pavement coating, compared with asphalt and concrete overlays Grande, ; Souza et al. Certain factors may difficult or even prevent the use of soil-cement, when the soil composition in general presents a wide variety of components, since this material comes from the stone transformation process and contains humus, chlorides, sulfates and harmful substances.
Sandier soils work better in soil-cement mixes, since they are stabilized with less amount of cement; the soil must contain clay, since it directly influences the composition of the blocks, providing a better adhesion cohesion among the particles of the materials of the mix, thereby preventing the loss of strength due to weathering conditions after molding.
There are examples of soil-cement studies dealing with: Other studies address its use with contaminated soil Rojas et al. The application of soil-cement blocks as coating layer for light-traffic pavements is described by Marchioni and Silvabut there are no further studies concerning the evaluation of mechanical properties durability, water absorption and compressive strength throughout their service life.
Characterization and compacting test results The blocks were built by manually mixing the right quantities of stabilized soil, cement and water. The material was conducted to its complete homogenization, which was identified when the mix achieved a uniform coloring. The specified water quantity to obtain the optimal humidity was added a few minutes later with a test tube.
In the sequence, the ball test is made by squeezing the mix with the hand and observing the mark left by the fingers, then the mass is dropped from a height of approximately one meter onto a hard surface and it is expected to dissolve when hitting the surface, otherwise the mass is too moist CEPED, After wetting, the mass was passed through a 2mm sieve, with the aim of dissolving the clods and increasing the homogeneity of the material. For controlling the manufacturing process, a batch of blocks was removed every blocks, more or less, making a total of four batches, identified as batch 1, batch 2, batch 3 and batch 4.
Los Suelos - Monografias.com. Perfil de suelo e
A certain number of blocks at day molding, average time corresponding to the starting date of the path construction, were removed and labeled as batch 5. Then, the tests of compressive strength, water absorption and durability were carried out in all the batches described the same tests used previously to define the proportioning of cement.
The productivity of the service was around 50 blocks per day; a team of 4 people took approximately 60 days to finish the work. The blocks were immersed in water for 6 hours and then they were superficially dried with an absorbent cloth.
The testing surface of the samples refers to the width of The blocks molded in the manual press come out with regular sides; therefore, no capping of the samples was needed for the rupture test.
The rupture test was made in a compression press using 6 to 9 blocks for each age 7, 14, 28, days and 4. After a 7-day curing, the three samples were weighed and put in the oven until they did not show any mass differences. After taking the samples out the oven, they were immersed in a tank with water for 24 hours, then removed from the water and superficially dried with a slightly wet cloth, weighed before 3 minutes have passedthereby determining how much water was absorbed by the blocks.
Rupture of the blocks 2. The durability test by wetting and drying complies with the Brazilian standard NBR Soil-Cement - Durability Test by Wetting and Dryingwhich determines the mass loss, the volumetric variation and the humidity variation resulting from the wetting and drying cycles in three samples blocksidentified as no.
Then, the three samples were subjected to six wearing cycles, which consisted of the following steps: The NBR standard refers to the brushing process with intensity of 15 N on the surface of a cylindrical sample. It states that the lateral surface requires 18 to 20 vertical brushings, with the brush placed with its lengthwise axis parallel to the lengthwise axis of the body of the sample.
craton sao francisco: Topics by trinamichaels.info
Each base is brushed four times, two in one sense and the other two in the sense crosswise to the previous ones. Since the tested blocks had a rectangular parallelepiped shape, instead of a cylindrical one, the standard was adjusted so that the number of brushings was proportional to each side of the block. Thus, each supporting side of the block was brushed eight times, since these sides 12 cm x 25 cm suffer direct load on the pavement, Figure 5b.