Einfluss von überkritischem Kohlendioxid auf die Eigenschaften von Zementstein

It is well known that the strengths of cement-based building materials are increased by carbonation. The hardened cement pastes produced from a commercially available i Portland cement with w/c ratios of 0.4 and 0.6 stored at different relative air humidities were treated with carbon dioxide under supercritical conditions in order to accelerate the carbonation process. The samples were tested for strength and characterized by X-ray diffractometry, nuclear spin resonance spectrometry, scanning electron microscopy and mercury intrusion porosimetry. The results of the investigation show that carbonation in supercritical CO₂ leads to a substantial increase in strength of up to about 400%. The course of the carbonation depends on the porosity and the moisture content of the sample. There is a discussion of the mechanism of carbonation of hardened cement paste under supercritical conditions.