Silica-Carbonate Building Materials Produced by Infiltration with Supercritical Carbon Dioxide
W. A. Ocampo, G. Bolaiios, and A. Salazar
Appears on pages(s):
agglomeration; calcite; carbonation; compressive
strength; lime; x-ray diffraction
Materials prepared by agglomerating white sand and slag with lime were subjected to infiltration with supercritical CO2 at temperatures from 3 1 to 40 OC, pressures from 7.4 to 10 MPa, and for periods from 20 to 120 min. This technique quickly promotes the carbonation reactions which are responsible for the development of the cementitious properties of the composite material. T h e extent of carbonation inside 50 mm cubes was monitored by using phenolphthalein, and the crystalline species were determined by X-ray diffraction. The results showed a high conversion (greater than 74%) of lime to calcite. After infiltration, all specimens exhibited a significant increase in compressive strength. From these results, we conclude that it is possible to produce improved carbonated materials in short processing times. The infiltration technique may be useful for producing construction materials from a number of siliceous waste products such as slag, construction rubbish and sludges from water-treatment plants.