The incorporation of waste rubber in cement-stabilized bearing layers exhibits drawbacks, such as a reduction in the mixture's strength. To address these drawbacks, various treatments can be applied to the rubber. This research investigates the treatment of rubber with sodium hydroxide and boiling water. The rubber treated using these methods was incorporated into a mixture defined within the „RubSuPave“ project that did not meet the compressive strength requirements for installation in the pavement's bearing layers. The results indicate that both rubber treatments lead to a decrease in the compressive strength of the mixture. After 7 days, the reduction is similar for both treatments, while better results were achieved after 28 days with the sodium hydroxide treatment. Additionally, after 28 days of curing, the rubber treated with sodium hydroxide exhibited increased stiffness in the stabilization mixture. Furthermore, the rubber surface was analyzed using a scanning electron microscope, revealing significant irregularities caused by both treatments. The applied methods did not result in an increase in the mixture's strength.