Dolomitic limes: evolution of the slaking process under different conditions

Dolomitic lime-based pastes were prepared in order to study the evolution of the compounds during the slaking process. Thermal studies as well as X-ray diffraction and FT-IR spectroscopy were used to confirm the formed compounds. The rate of the hydration of calcium and magnesium oxides has been determined under different conditions: atmospheric conditions, CO2-rich and enclosed environment without CO2. Also the lime powder evolution without water added was studied. Whereas CaO hydrates at a higher rate, MgO is very dependent by its particle size distribution and stirring. The paper also focuses on the carbonation process. Given that carbonation is the most usual hardening process in lime pastes, its knowledge is necessary to understand the mechanical behavior of these pastes. In an excess of water, calcium hydroxide carbonates giving calcite if exposed to CO2. In lime powder, another mechanism has been established through vaterite formation. Magnesium hydroxide does not carbonate under normal conditions. In a CO2 atmosphere nesquehonite (MgCO3.3H(2)O) has been checked found as a result of carbonation. (C) 2004 Elsevier B.V. All rights reserved.