Navegando por Assunto "Umidade"

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Acesso aberto (Open Access)
Argamassas para dessalinização de alvenaria mista de edifício histórico de Belém
(Universidade Federal do Pará, 2013-09-05) LOUREIRO, Alexandre Máximo Silva; SANJAD, Thais Alessandra Bastos Caminha; ANGÉLICA, Rômulo Simões; http://lattes.cnpq.br/7501959623721607; http://lattes.cnpq.br/8950586647715771
In the historical monuments of Belém structural masonry, along with the foundations and pillars, are responsible for supporting the building (VASCONCELLOS, 1979). These masonry are made of stone and solid bricks with lime mortar setting and can present various pathologies among which stand out the action of salt efflorescence and moisture. These two agents cause detachment of layers, mortar spraying, the appearance of cracks in masonry, and whitish appearance (HENRIQUES, 1994; CHAROLA, 2000). The research has as main objective the identification, characterization and attenuation of salt efflorescence, through study of the masonry of the right transept of the Church of St. Alexandre, located in historic downtown of Belém- PA. For this, laboratory techniques were used in order to understand the favorable process conditions of salt efflorescence, the damage to the materials, the kinds of salts and which materials are effective for desalination. First was the mapping the masonry and mapping damage to verify the current situation and the most degraded areas. Was subsequently performed the physical, chemical and mineralogical characterization: 1) physical characterization by sieve analysis, trace analysis and analysis of the moisture content of the masonry, 2) chemical characterization through qualitative and quantitative testing of salts and 3) characterization mineralogy by X-ray diffraction. The X-ray diffraction was also used to evaluate the efficacy of four types of desalination mortars containing clay (bentonite and kaolin) and sand in different ratios. At the end of the study it was found that the suggested techniques for characterization and mapping of the masonry proved efficient and aided in the correct diagnosis of the existing problem. Moreover, the research showed which kinds of mortar are recommended to desalination of masonry damaged by salt efflorescence.
Acesso aberto (Open Access)
Regimes térmico e hídrico em solos sob ecossistemas naturais e área agrícola no Leste da Amazônia
(Universidade Federal do Pará, 2007-12-14) CARVALHO, Saulo Prado; SOUZA, José Ricardo Santos de; http://lattes.cnpq.br/2797414407717271
Soils temperature and moisture are variables whose knowledge is required to Determine the energy and water budgets in the biosphere. The thermal and hydric regimes of soils beneath each ecosystem, present considerable variations, according to their mineralogy, the local climate and vegetation. In this context, soil temperatures and moistures were measured under three ecosystems existing over the eastern portion of the Amazon Region, namely: native forest (Caxiuana's National Forest, 01° 42' 30" S and 51° 31' 45" W), pasture area (Soure, 00° 43' 25" S and 48° 30' 29" W) and cultivated area (Igarape-Acu, 01° 07' 59" S and 47° 36' 55" W). Field data at the forest and pasture sites were collected between December, 2001 and February, 2005; while at the cultivated area, the monitoring was limited to the August, 2003 to February, 2005, period. These observations of soil physical variables were analyzed taken into consideration the simultaneously measured meteorological variables such as the incoming solar radiation flux and pluviometric precipitation, which directly impacted the soil variables at each site selected for study. The soil temperatures were monitored by means of thermal sondes at 0.05, 0.2 and 0.5 m depths. Heat fluximeters, measured heat flux at 0.05 and 0.2 m depth levels. The upper 0.3 m soil layer bulk moisture was measured by double probe Time Domain Reflectometer (TDR) sondes at each site. Analyses were made, considering the soil responses during the local dry and rainy seasons at these three representative ecosystems of eastern Amazonia. Apparent thermal diffusivity estimates were made by the amplitude and phase methods, using the daily heating pulse propagation data in these soils. The results showed quite different values. However, the first approach seemed to be more reliable and suitable to numerical modeling. As expected, considering their small vegetation cover, the soil temperatures at the upper levels, presented larger variations at the pasture and cultivated sites. Unexpectedly, the temperatures at 0.5 m depth beneath the forest showed larger amplitude variations than at 0.2 and 0.05 m depths. The numerical modeling of time variations of temperature, as function of depth, for each soil was made through the harmonic method. The results showed that the first harmonic represented over 90% of the total variation of the observed daily pulse of temperature for the pasture and cultivated areas at 0.2 and 0.05 m depths. Similar performance of the modeling was observed for the forest at 0.05 and 0.20 m levels. The magnitude of heat fluxes beneath the pasture and cultivated sites reached values six times larger than those observed beneath the soil of the forest. The results also show that, for the upper 0.30 m layer of soils, the bulk moisture beneath the forest is larger than under the other ecosystems studied in this work. This result apparently is due to the forest's protection against the soils surface evaporation. An analysis of the seasonal and daily behavior of the soils temperature and moisture in response to the incoming solar radiation and precipitation are presented. Case studies of the rate of soil moisture losses after significant water recharge by precipitation events were also analyzed. Some estimates of daily water depletion and even, night recharge of moisture by rising water from lower layers to the 0.30 m layer were made. This work analyzed the largest time series of soil temperature and moisture data taken at high sampling rates, available so far, for eastern Amazonia. It was possible to characterize the differences of these physical variables regimes, beneath three important ecosystems in this Region. Further studies of the minerals and organic materials in these soils, as well as the foliar area and biomass indexes of their vegetation covers, would improve the comprehension of the regimes described in this work.