Efeitos da adição da cal hidratada na estabilização de um solo sedimentar para pavimentação urbana na região de Curitiba

Urban paving is of paramount importance for a city, both socioeconomic and in quality of life. The urban flooring not different so-called road surface are constituted by a set of horizontal layers, overlaid on the ground, which have the main function of supporting the actions induced by the vehicle redistributing the stresses transmitted to the ground. Soils are important materials for the execution of paving, mainly because they are part of the basic structure of the floor and mostly be available in abundance, with a very low cost, however, their properties usually do not meet the requirements necessary to perform the floor. The soil stabilization for the implementation of urban pavement bases and sub-bases is an increasingly important aspect in the current situation, because always there is the concern with the environment, and there is now the clear awareness that every effort should be made to minimize the effects caused by the exploitation of deposits and deposition of material. In this sense this work presents the effects of adding different proportions of lime to stabilize a sedimentary soil sample from the urban area of the city of Curitiba. It selected a sample quantity of soil in the region to study the stabilization insertion of hydrated lime type (CHIII) powder. The two variables in the study are related to the content of lime mixed with the soil at 0% percentages of 3%, 6%, 8% and 16%, and cure times at which these mixtures were subjected to (0, 7, 14, 28 and 56 days). The tested mixtures were prepared from dosages defined by two methods: one checking the chemical behavior of the samples by means of changes in pH values, and the second analyzing the mechanical behavior through the RCS values. It has been found that the chemical stability analyzed by addition of lime, provided an average increase of RCS in most soil samples studied, because of some physical and chemical characteristics thereof. For mixtures with 6%, 8% and 16% of lime after 28 days of curing, the average RCS was 0,57 MPa, 1,06 MPa and 2,37 MPa, respectively, for the normal proctor, and as for intermediate proctor, in the same curing time and on the same percentages RCS results were 0,54 MPa, 1,04 MPa and 2,71 MPa, respectively. In global terms, the soil-lime mixtures studied showed acceptable behavior by law to use as layers of sub-base. However, only the mixture with 16% of lime, at 28 days, is recommended for use on floors bases. Even so, the mixtures studied constitute a good alternative economic and socio-environmental.

Estudo numérico do impacto das emissões veiculares e fixas da cidade de Manaus nas concentrações de poluentes atmosféricos da região amazônica

The main aim of this study was to evaluate the impact of the urban pollution plume from the city of Manaus by emissions from mobile and stationary sources in the atmospheric pollutants concentrations of the Amazon region, by using The Weather Research and Forecasting with Chemistry (WRF-Chem) model. The air pollutants analyzed were CO, NOx, SO2, O3, PM2.5, PM10 and VOCs. The model simulations have been configured with a grid spacing of 3 km, with 190 x and 136 y grid points in horizontal spacing, centered in the city of Manaus during the period of 17 and 18 of March 2014. The anthropogenic emissions inventories have gathered from mobile sources that were estimated the emissions of light and heavy-duty vehicles classes. In addition, the stationary sources have considered the thermal power plants by the type of energy sources used in the region as well as the emissions from the refinery located in Manaus. Various scenarios have been defined with numerical experiments that considered only emissions by biogenic, mobile and stationary sources, and replacement fuel from thermal power plant, along with a future scenario consisting with twice as much anthropogenic emissions. A qualitative assessment of simulation with base scenario has also been carried out, which represents the conditions of the region in its current state, where several statistical methods were used in order to compare the results of air pollutants and meteorological fields with observed ground-based data located in various points in the study grid. The qualitative analysis showed that the model represents satisfactorily the variables analyzed from the point of view of the adopted parameters. Regarding the simulations, defined from the base scenarios, the numerical experiments indicate relevant results such as: it was found that the stationary sources scenario, where the thermal power plants are predominant, resulted in the highest concentrations, for all air pollutants evaluated, except for carbon monoxide when compared to the vehicle emissions scenario; The replacement of the energy matrix of current thermal power plants for natural gas have showed significant reductions in pollutants analyzed, for instance, 63% reductions of NOx in the contribution of average concentration in the study grid; A significant increase in the concentrations of chemical species was observed in a futuristic scenario, reaching up to a 81% increase in peak concentrations of SO2 in the study area. The spatial distributions of the scenarios have showed that the air pollution plume from Manaus is predominantly west and southwest, where it can reach hundreds of kilometers to areas dominated by original soil covering.