Cement-based materials used to seal geothermal or deep oil wells are exposed to severe conditions. Optimizing engineering properties such as strength and permeability is therefore very important. We have synthesized hydroceramic materials for such applications based on the CaOAl2O3SiO2H2O (CASH) system and cured them over a range of temperatures (200 °C to 350 °C). Depending on starting composition and curing temperature, we form hydroceramics of complex and diverse mineralogy and microstructure. Minerals found include portlandite, jaffeite, xonotlite, gyrolite, 11Å tobermorite, truscottite, hydrogarnet and calcium aluminum silicate hydrate. These cement-based hydroceramic materials develop complicated pore structures which strongly affect bulk properties. We report the compressive strength and permeability of these materials and how these bulk engineering properties are related to microstructure. Compressive strength was found to be in the range 252 MPa and intrinsic permeability in the range 0.53300 x 1017 m2. Scanning electron microscopy (SEM) was employed for imaging the hydroceramic microstructures. Finally we have computed the permeability from 2-D SEM images by using the Stokes equation solver (Permsolver) applied to reconstructed 3-D images. These results are in very good agreement with experimental values.
Citation: Journal of the American Ceramic Society
Pub Type: Journals
Building technology, compressive strength, hydroceramic, microstructure, mineralogy, permeability.