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MgO-SiO 2 cement was produced by combined calcination of MgCO 3 and kaolin as raw materials, at a MgCO 3 /kaolin mass ratio of 3.0 and 800 °C for 45 min. Separate calcination of MgCO 3 and kaolin was also conducted under the same conditions. Raw materials were characterized based on their chemical composition, bulk density, particle size distribution, XRD, FTIR, and BET specific surface area, and the MgO-SiO 2 cement produced was analyzed using XRD, FTIR, SEM/EDS, BET specific surface area, and particle size distribution. Pastes were produced to characterize microstructure and the reaction process (XRD, FTIR, TGA, isothermal calorimetry, chemical shrinkage, and SEM/EDS), and mortars to assess compressive strength. The results of BET and SEM/EDS analyses of the cements confirmed that combined calcination increased particle adhesion. Microstructural analyses of pastes after 28 days of curing at 25 °C showed the formation of a dense matrix of M-A-S-H reaction product, with aluminum incorporated into the M-A-S-H structure; brucite and hydrotalcite were also generated after the reaction process. Paste reaction results demonstrated that combined calcination produced cement with a higher degree of reaction after 72 h at 25 °C. The highest compressive strength (42.0 MPa) in mortars obtained by combined calcination was recorded after 28 days of curing at 25 °C, 223 % higher than that of separately calcined cement (13.0 MPa). As such, this study successfully applied combined calcination to produce a more strength MgO-SiO 2 cement. [ABSTRACT FROM AUTHOR]

Abstract: The current trend of increasing the electricity production from wind energy has led to the installation of wind farms in areas of greater orographic complexity, raising doubts on the use of simple, linear, mathematical models of the fluid flow equations, so common in the wind energy engineering. The present study shows how conventional techniques, linear models and cup anemometers, can be combined with flow simulation by computational fluid dynamics techniques (nonlinear models) and measurements by sonic anemometers, and discuss their relative merits in the characterisation of the wind over a coastal region—a cliff over the sea. The computational fluid dynamic techniques were particularly useful, providing a global view of the wind flow over the cliff and enabling the identification of separated flow regions, clearly unsuitable for installation of wind turbines. These locations display a pulsating flow, with periods between 1 and 7min, in agreement with sonic anemometer measurements, and both a turbulence intensity and a gust factor well above the wind turbine design conditions. [Copyright &y& Elsevier]