To ensure well integrity during carbon capture and storage (CCS) operations, it is essential to understand the effects of carbon dioxide (CO2) on the cement at high-pressure and temperature conditions. There are several providers of CO2-resistant types of cement for the oil and gas industry, promising the integrity of their products. However, there are no standardized testing procedures to test their cement. This thesis aims to create a new testing methodology for CO2-resistant cement types and to investigate the quality of a CO2-resistant cement using the proposed methodology. The new testing methodology uses two types of high-pressure vessels. Smaller autoclaves are used to condition cement specimens (2" height x 1" diameter) with CO2. These specimens are used to analyze the compressive strength, mineralogical composition, and inhomogeneities in the cement matrix at different conditioning stages. The second pressure vessel is the CT-Scannable CO2 Cell, in which the propagation of the carbonation front is measured using a medical CT scanner. By combing the results of both procedures, an estimation of the material's behavior under downhole conditions can be made. The results from this study can assist in the prevention of well integrity problems due to CO2 leakage, therefore mitigating health, safety, and environmental risks and increasing the efficiency and economic success of CCS projects.