MICROSTRUCTURAL ASPECTS OF THE REACTION BETWEEN ORDINARY PORTLAND CEMENT AND SUPERCRITICAL CARBON DIOXIDE

摘要

The observed reaction between inorganic materials and carbon dioxide at elevated pressures will be complicated by the carbonate that is precipitated as samples are returned to equilibrium with the atmosphere. By handling samples in different ways it is possible to examine the carbonate formed at different point and therefore examine the morphology of the products formed under peak conditions and as a consequence of subsequent porewater degassing. An uneven poorly crystalline reaction product is observed to form first coating grains of ordinary Portland cement exposed to supercritical CO_2 at 105℃ and 80bar for 24hours. This is overlain by fine slightly elongate crystals that form after the sample has been removed from the reaction chamber.