The cement industry is facing a global problem of environmental pollution during cement production. To reduce the negative impact on the environment, the possibility of using supplementary cementitious materials – SCMs, e.g. industrial by-products or natural materials, as a replacement for part of the cement in concrete has been already investigated for many years. Calcium aluminate cement (CAC) has been used for more than 100 years and is mostly used for special purposes where resistance to aggressive environments is required. However, the application of CAC is limited by the occurrence of the conversion process, which increases the porosity of the cement matrix and reduces its mechanical properties. The use of SCMs as a replacement for part of the CAC could reduce the negative environmental impact of cement production and improve the mechanical properties of concrete, especially when exposed to higher curing temperatures. Previous research has shown that the application of blast furnace slag reduces the impact of the conversion process. However, due to challenges with the availability and cost of slag, there is a need to investigate other possible SCMs. In this dissertation, calcined clay, which is available in the region and has a medium kaolin content, was used. Although the rate of the conversion process is reduced by the use of SCMs, the question of the durability of such binders arises. In the first phase of this dissertation, the research focused on the influence of slag and calcined clay on the mechanical properties of CAC cement. At the same time, the changes in hydration products and pore structure were analysed under the influence of two different curing regimes (20°C and 38°C). It was found that calcined clay can be used as a replacement for part of the CAC instead of slag to reduce the effects of the conversion process. Furthermore, the results show that the addition of calcined clay to CAC strätlingite is formed, which densifies the structure and inhibits the conversion process. In the second phase, the research focused on evaluating the durability of concrete based on CAC with and without the addition of slag or calcined clay. The durability assessment included tests on resistance to carbonation, resistance to chloride penetration, resistance to acid attack and sulphate resistance. The tests were carried out on systems before and after the conversion process, whereby the conversion process was accelerated by curing at 38°C. The results show that the addition of slag or calcined clay reduces the resistance of CAC under different environmental conditions. However, while the resistance of systems without SCMs was significantly affected by these influences, the resistance of systems with slag or calcined clay was only slightly affected after the conversion process. The research conducted in this dissertation shows that slag and calcined clay can be used as a replacement for 30% of CAC. Understanding the effects of slag and clay on microstructural changes, their contribution to mitigating the effects of the conversion process and their effects on durability properties allows for a wider application of CAC-based systems.