Degradation of Portland cement under supercritical CO₂ conditions (scCO₂) is one of the major concern in geological sequestration projects. This paper presents the research on two novel types of binders considered to display a CO₂ corrosion resistance potential: (1) Portland cement partially replaced with 20, 30 and 40 wt % of zeolite and blended with Styrene-Butadiene (SB) Latex and (2) geopolymer based on lime-slag and lime-pozzolan blends. Specimens were placed in an autoclave, covered with water, heated up to 100 °C and pressurized with 7 MPa CO₂ in order to simulate CO₂ environment in the Croatian wellbore. On behalf of tests on compressive strength, porosity, permeability and alkalinity, as well as thermogravimetry, X-ray diffraction and SEM microstructural analyses of samples at various penetration depths, carbonation mechanisms were discussed. Portland-Zeolite composites have been argued as potential CO₂ resistant cement systems, with an replacement rate below the minimally tested addition of 20 wt %, as excessive replacement rates resulted in an increase in porosity and permeability. Geopolymer composites based on lime activation unfortunately haven't exhibited required properties for application in well cementing of CO₂ injection wells. Calcium carbonate polymorphs precipitated throughout the whole specimen thickness of all samples, but preferably in mixtures based on Ca-richer raw materials. A re-precipitation of calcium carbonate filled in the porosity preferentially at the 0.5 mm surface layer of PC-based specimens, due to the outward diffusion of calcium at the early stage of carbonation.